Grundfos A2 Water Engineering[1]

GRUNDFOS ENGINEERING MANUAL

Water Systems Engineering Manual for Groundwater Supply and Special Applications

U.S.A.GRUNDFOS Pumps Corporation 17100 West 118th TerraceOlathe, Kansas 66061Phone: (913) 227-3400 Telefax: (913) 227-3500

CanadaGRUNDFOS Canada Inc. 2941 Brighton Road Oakville, Ontario L6H 6C9 Phone: (905) 829-9533 Telefax: (905) 829-9512

MexicoBombas GRUNDFOS de Mexico S.A. de C.V. Boulevard TLC No. 15Parque Industrial Stiva AeropuertoC.P. 66600 Apodaca, N.L. Mexico Phone: 011-52-81-8144 4000 Telefax: 011-52-81-8144 4010

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Introduction

1A Water Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2Sources, Quality, Quantity & Rights

1B Groundwater & Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8Supply, Hydraulics, Construction & Treatment

1C Water Quality & Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-37Drinking Water Regulations, Characteristics & Treatment

1D Water System Capacity Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-59Rural, Public and Irrigation Systems, Sizing

1E Pumping, Distribution and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-81Hydro-Pneumatic System

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TABLE OF CONTENTS1. WATER SUPPLY PLANNING

2A Pump Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2General Centrifugal Pump Operation and Types (ie. types made by Grundfos), Submersible Overview

2B Hydraulic Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15Density, Specific Gravity and Weight, Pressure and Head, Flow, Vapor Pressure, NPSH, Power andViscosity

2C Pump Hydraulic Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-24Affinity Laws, Specific Speed, Speed - Torque, System Head Curves, Parallel and Series Flow, MinimumFlow and Thrust

2D Pumping System Application Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-38Cavitation, Entrained Gas, Entrained Solids, Water Hammer, Downhole Check Valves, Corrosion, Testing,Power Consumption and Cost

2E Engineering Properties of Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-60

2. PUMP HYDRAULICS & APPLICATION CONSIDERATIONS

3A Electrical & Power Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2AC Power, Impedance, Power Factor, Phase Converters

3B Induction Motor Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6Voltage, Frequency, Efficiency, 3-Phase, PF, Insulation Systems

3C Motor Starting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26Full Voltage Starting, Reduced Voltage Starting

3D Grundfos Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-32CU3 Controller, R100 Remote, SM100 Sensor Module, G100 Gateway Communication Interface

3. ELECTRICAL – POWER, MOTORS AND CONTROL

4A Submersible Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2Overview, Motor Types, Thrust Bearings, Generator Use in Submersible Application

4B Submersible Motor Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18Required Cooling, Motor Derating, Motor Sleeves, Special Applications

4C Motor Insulation Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-24Dielectic Absorption Ratio

4D Submersible Power Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-26Cable Selection

4. SUBMERSIBLE MOTORS


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5A Large Submersible Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2Product Overview, Features and Benefits, Pump Models, Single Stage Data, Submersible Pump Data

5B Exploded View Drawings and Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4Pump Drawings, Materials Used in Construction

5. GRUNDFOS SUBMERSIBLE PRODUCTS

6A Submersible Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2Sump Pumps, Can Pumps

6B Sizing and Selection Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12Calculation of Submersible Pump and Motor Size, Installation and Start-Up Rules

6. SUBMERSIBLE APPLICATIONS AND SIZING

7A Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2Pipe Data, Flange Dimensions, Friction Loss, Equivalent Pipe Capacity, Pipe Flow Estimating, Conversion Tables

7B Reference List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-31

7. TECHNICAL APPENDICES AND REFERENCES

GRUNDFOS ENGINEERING MANUALJANUARY 1999

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GrundfosEngineering Manual for

Groundwater Supply and Special Applications

INTRODUCTION

FOREWORD

This manual was developed to serve three (3) principal purposes:

1. To provide the water supply professional with a technical primer applicable to many of the various systemconsiderations and issues associated with the development of a new or expansion of existing groundwatersupply systems commonly encountered in the United States.

2. To provide a single source reference for commonly required information associated with the design ofgroundwater supply systems utilizing submersible pumping equipment and selective special applications

3. To acquaint the water supply professional with the use, application and advantages of Grundfos stainless steelsubmersible pump and control products.

We have taken considerable time and care to make the presentation as convenient and easy to use as possible;however, we realize there is always room for improvement and invite comment. It is our sincere hope that the userfinds this manual a useful reference tool in the design and construction of groundwater systems, and associatedsubmersible pump products.

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A global business

With over 11,000 employees worldwide, and annualproduction of 10 million pump units per year, Grundfos isone of the world’s leading pump manufacturers. Over 60Grundfos Companies around the globe help bring pumps toevery corner of the world, supplying drinking water toAntarctic expeditions, irrigating Dutch tulips, monitoringgroundwater beneath waste heaps in Germany, and airconditioning Egyptian hotels.

Efficient, sustainable productsGrundfos is constantly striving to make its products moreuser-friendly and reliable as well as energy-saving andefficient. Our pumps are equipped with ultra-modernelectronics allowing output to be regulated according tocurrent needs. This ensures convenience for the end-user,saves a great deal of energy and, in turn, benefits theenvironment.

Research and developmentIn order to maintain its market position, Grundfos takescustomer research to heart when improving or developing

new products. Our Research and Development departmentmakes use of the latest technology within the pump industryin search of new and better solutions for the design andfunction of our pump solutions.

Corporate valuesThe Grundfos Group is based on values such as sustainability,openness, trustworthiness, responsibility, and also onpartnership with clients, suppliers and the whole of societyaround us, with a focus on humanity that concerns our ownemployees as well as the many millions who be-nefit fromwater that is procured, utilized and removed as wastewaterwith the help of Grundfos pumps.

Introductioniv

Technology and business development center at Group headquarters in Denmark


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Grundfos North America

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IT IS OUR MISSION – the basis of our existence – tosuccessfully develop, produce, and sell high qualitypumps and pumping systems worldwide, contributingto a better quality of life and a healthier environment.

Fresno, California

Monterrey, Mexico Allentown, Pennsylvania Oakville, Canada

Olathe, Kansas

North American headquarters in Olathe, Kansas

Manufacturing in Fresno, California

Service, distribution and light assembly in Allentown, Pennsylvania

Sales and assembly located in Canada and Mexico


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DisclaimerConsiderable effort has been expended to insure the accuracy of the information presented in this manual and tothe best of our knowledge, the information contained is accurate.

Grundfos, it’s dealers and distributors, and authors of and contributors to this manual assumes no liability orwarranty whatsoever, expressed or implied, for the accuracy, completeness and/or reliability of such informationcontained herein. Final determination of the suitability of the information or products for the use contemplated isthe sole responsibility of the user. We recommend that anyone intending to rely on the guidelines andrecommendations mentioned in this manual satisfy themselves as to the suitability, fitness for a particular purposeand compliance to all applicable safety and public health codes before implementation.

The format, presentation and a majority of the tabulated information is copyrighted by Grundfos. Manual materialsmay be copied for individual use only.

PRODUCT LINES

GroundwaterGrundfos offers a wide range of “no lead” submersible pumps for domestic groundwater system applications. Builtof rugged stainless steel and superior components, Grundfos submersibles are regarded as the toughest, mostreliable pumps on the market.

Commercial/IndustrialGrundfos pumps provide a multitude of commercial uses, providing high capacity pumps for universities, hospitals,hotels and high-rise buildings. Grundfos is also well recognized for industrial applications including automotiveplants, paper mills, food processing machinery, offshore platforms and reverse osmosis systems.

Plumbing and HeatingGrundfos offers a full line of circulators for hydronic, hot water, and solar energy applications. Currently there aremore than 3 million Grundfos circulators systems in use throughout the world.

Sewage, Effluent and Sump PumpsGrundfos offers a line of sewage, effluent and sump pumps for applications involving residential and lightcommercial sewage, septic system effluent and residential sump and waste water removal.

EnvironmentalGrundfos Redi-Flo submersible pumps are designed for environmental groundwater monitoring, sampling andclean-up operations.

Grundfos Pumps Corporation is one of the first U.S. pump manufacturers to be ISO 9001 certified for high qualitystandards throughout its entire product line. Advanced robotics fabrication, skilled applications engineers,CAD/CAM & Catia engineering, on-going educational training, and service and repair facilities all contribute tosuccess at Grundfos.


Section 1

Section 1A Water Supply Planning Fundamentals



SECTION 1:WATER SUPPLY PLANNING

1A WATER SUPPLY PLANNING FUNDAMENTALS

• Water Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2• Water Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5• Quantity of Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6• Water Rights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

1B GROUNDWATER & WELLS

• Groundwater as a Water Supply Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8• Groundwater Hydrology & Well Hydraulics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11• Well Design & Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17• Well Disinfection & Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-34

1C WATER QUALITY & TREATMENT

• Drinking Water Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-37• Water Quality for Agriculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-44• Water Quality Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-45• Water Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-50

1D WATER SYSTEM CAPACITY REQUIREMENTS

• Residential / Domestic and Farm Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-59• Public Water Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-65• Agricultural and Turf Irrigation Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-69• Curves for Sizing Domestic Water Demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-74

1E PUMPING, DISTRIBUTION & STORAGE

• Pumping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-81• Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-87• Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-89• Hydro-Pneumatic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-92

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Section 1A Water Supply Planning Fundamentals1-2

1A WATER SUPPLY PLANNING FUNDAMENTALSPlanning a water-supply system begins with the identification of available water sources. The quality of water fromthose sources must then be investigated, as well as the quantity of water that each source can reliably supply.Finally, before a source can be selected and developed, the legal rights to the water from that source must beestablished.

Water SourcesThere are two principal sources suitable for use as a potable water supply; groundwater and surface water. In someinstances, a water supply may use a combination of both sources. Both sources are part of, and renewed by thehydrologic cycle. Refer to Figure 1-1 for a graphical depiction of the Hydrologic Cycle.

Groundwater. Groundwater supplies are important sources of water supply which have a number of advantagesover surface supplies. They may require little or no treatment, have uniform temperature throughout the year, arecheaper than impounding reservoirs, and amounts of water available are more certain. They are relativelyunaffected by drought in the short term.

Groundwater is the portion of water that infiltrates the soil not utilized by plants (evapo-transpiration) or directlyevaporated. This unused water eventually reaches the zone of saturation through the force of gravity. Water in thezone of saturation is referred to as “groundwater.” The upper surface of the zone saturation, if not confined byimpermeable material, is called the water table. The saturated zone may be viewed as a huge natural reservoirwhose capacity is the total volume of pores or openings in the rocks that are filled with water. Groundwater maybe found in one continuous body or several separate strata.

The thickness in the zone of saturation varies from a few feet to many hundreds of feet. Factors that determine itsthickness are: the local geology, the availability of pores or openings in the formations. Movement of water withinthe zone is a result of gradient changes as a result of natural or man made recharge and discharge. Formations orstrata within the saturated zone from which ground water can be obtained for beneficial use are called “aquifers.”An aquifer is a water-saturated geologic unit that will yield water to wells or springs at a sufficient rate as to be apractical sources of water supply. Sand, gravel and sandstone aquifers provide the best aquifer media for highcapacity water well construction.

Types of Wells. In the ordinary or water-table well the water rises to the height of the saturated material surroundingit. There is no pressure other than atmospheric upon the water in the surrounding aquifer. An artesian well is onein which the water rises above the level at which it is encountered in the aquifer because of pressure in theconfined water of the aquifer. A flowing well is an artesian well where the pressure raises the water above thecasing head. Heavy draft upon the aquifer may so lower the hydraulic gradient that a flowing well will cease toflow. Figure 1-2 illustrates artesian conditions.

Pumping will cause a lowering of the water table near the well. If pumping continues at a rate that exceeds the rateof ground water recharge, a condition known as ground water mining occurs. Prolonged groundwater mining willincrease pumping cost as the water level drops, change quality and can promote salt-water encroachment in coastalareas.

Springs: An opening in the ground surface form which ground water flows is a spring. Water may flow by force ofgravity (from water-table aquifers) or be forced out by artesian pressure. Springs constitute only a very small portionof groundwater supply sources.

Surface Water. Precipitation that does not enter the ground through infiltration or is not returned to the atmosphereby evaporation, flows over the ground surface and is classified as direct runoff. Direct runoff is water that movesover saturated or impermeable surfaces into stream channels, lakes or artificial storage sites. The dry-weather (base)flow is derived from groundwater or snowmelt. Runoff from ground surfaces may be collected in either natural orartificial reservoirs. A portion of the water stored in surface reservoirs is lost by evaporation and by infiltration tothe groundwater.


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Section 1A Water Supply Planning Fundamentals 1-3

Figure 1-1: Schematic Diagram of the Hydrologic Cycle

Figure 1-2: Subsurface and ground water phase of the hydrologic cycle


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Potable Water Available in the United States. It is estimated that the earth contains 380 million cubic miles ofwater. About 2.5% of this is fresh water and of this, 1.5 % is in the form of ice at the polar caps. Slightly less than1% of all water therefore remains available to man for potable use. One percent sounds like a small amount,however, it represents a tremendous quantity, far outranking all other natural resources.

Water is not used up like other resources. By virtue of the hydrological cycle it is continually returned to its source.It has been estimated that ground waters in the United States have been depleted less than 1/4% of 1% in 500 years.Of all usable water available on earth, approximately 26% exists in the United States, 77% of which is contained inunderground aquifers, 23% as surface water (21% in lakes and 2% in rivers and reservoirs).

Approximately 47% of the water presently used in the United States comes from surface water. The remaining 53%is taken from groundwater sources (source: USGS 1986 National Water Summary). The major groundwater regionsof the continental United Sates are shown in Figure 1-3.


Figure 1-3: Groundwater Availability and Regions in the U.S.

Groundwater77%

Lakes21%

Rivers

Reservoirs

Groundwater53%

Surface Water47%

Fresh Water Availability in the U.S Groundwater vs. Surface Water in the U.S.

Major Groundwater Regions of the Continental U.S.


Section 1


Water QualityPrecipitation in the form of rain, snow, hail or sleet contains very few impurities and virtually no bacteria. It maycontain trace amounts of minerals, gases, and other substances as it forms and falls through the earth’s atmosphere.Once precipitation reaches the earth’s surface, however, mineral and organic substances, microorganisms, and otherforms of pollution (which tend to lower water quality) enter the water.

When water runs over or through the ground surface, it may pick up soil particles. This is noticeable in the wateras cloudiness, or “turbidity.” Water also picks up particles of organic matter and bacteria. As surface water seepsinto the soil and through the underlying material to the water table, most suspended particles are filtered out. Thisnatural filtration is partially effective in removing bacteria and other particulate materials; however, the chemicalcharacteristics of the water may change and vary widely when it comes in contact with mineral deposits in the soil.

The widespread use of synthetically produced chemical compounds; including pesticides, insecticides and solvents,has had a pronounced effect on water quality. Many of these materials are known to be toxic. Others have certainundesirable characteristics, which interfere with water use even when these materials are present in relatively smallconcentrations.

The Safe Drinking Water Act. When selecting a source as a water-supply for potable purposes, it is necessary tocarefully examine all water-quality factors that might adversely affect the intended use of the water source. As aminimum, the quality of the water must be such that it will meet (after treatment, if necessary) the standardsestablished under the drinking water regulations of the Federal Safe Drinking Water Act (SDWA), as well as anyadditional state or local standards. When selecting a water source it is also important to consider othercharacteristics, including the water’s palatability, its aesthetic quality and its potential for corrosion or scaling ofpipes.

A detailed discussion of the SDWA and associated water quality issues are presented in Section 1C.

Treatment. In evaluating a source based on water quality, the availability and costs of water-treatment techniquesto remove undesirable constituents must be considered. Conventional water treatment techniques; such as aeration,sedimentation, coagulation/flocculation, filtration, softening, fluoridation, adsorption and disinfection have beenused for decades to produce potable water for large municipal water systems. The same techniques can be used toproduce water of potable quality for smaller systems. In addition, small package treatment units using membraneseparation processes, primarily reverse-osmosis (RO), are commercially available. These units, although oftenuneconomical for large utilities, may be a viable alternative for a small system, especially for use with brackishground water sources.

Water quality characteristics can be broken into four categories; physical, chemical, biological and radiological.Some of the treatment methods that a small utility might economically use to reduce objectionable contaminants toan acceptable level are discussed in Section 1C.

Sanitary Survey. A sanitary survey is important in the development of a new water supply and is often aregulatory requirement for permit. The sanitary survey should be made in conjunction with the collection of initialengineering data covering the development of a given source and its capacity to meet existing and future needs.The sanitary survey should include the detection of all health hazards and the assessment of there present andfuture importance. Only persons trained and competent in public health and familiar with water supply engineeringshould conduct the sanitary survey. In the case of an existing supply, the survey should be made at a frequencycompatible with the control of the health hazards and the maintenance of good sanitary quality, or as required bythe governing regulatory agency. A general outline of the issues/ factors that should be investigated or consideredin a ground water sanitary survey is listed as follows:

A. Character of local geology and slope of ground surface.

B. Nature of soil and underlying porous strata - whether clay, sand, gravel, rock (especially porous limestone);coarseness of sand or gravel; thickness of water-bearing stratum, depth to water table; location, log andconstruction details of local wells in use and abandoned.

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C. Slope (gradient) of water table.

D. Extent of drainage area likely to contribute water to the supply.

E. Nature, distance and direction of local pollution sources.

F. Possibility of surface-drainage water entering the supply and of wells becoming flooded, methods of protection.

G. Methods used for protecting the supply of pollution by means of sewage treatment, waste disposal, etc.

H. Water quality data collected from test wells or permanently constructed monitoring wells constructed in advanceof production wells.

I. Well construction:1. Total depth of well..2. Casing - diameter, wall thickness, material and length from surface.3. Screen or perforations - diameter, material, construction, locations and lengths.4. Formation seal - material (cement, sand, bentonite, etc.), depth intervals, annular thickness and method of

placement.

J. Protection of well head - presence of sanitary well seal, casing height above ground, floor or flood level,protection of well vent, protection of well from erosion and animals.

K. Pumphouse construction (floors, drains, etc.), capacity of pumps, drawdown when pumps are in operation.

L. Availability of an unsafe supply, usable in place of normal supply, hence involving danger to the public health.

M. Disinfection - equipment, supervision, test kits or other types of laboratory control..

Note: Not all the items listed are pertinent to any one supply.

Quantity of Water An important step in selecting a suitable water-supply source is determining the demand that will be placed on it.The four principal issues that must be addressed in conjunction with determining system water quantity needs areusage, flow, pressure and storage.

Usage (consumption). The quantity of water must be established to determine the adequacy of the source tomeet demand; as well as establishing infrastructure requirements. The quantity of water required to besupplied by a system is most easily calculated when the ultimate or end use is known. Quantity requirementsare normally estimated based on average daily usage (consumption) and is expressed in gallons per day (gpd)or gallons per capita per day (gpcd) depending on the size of the system.

Metering can significantly reduce consumption within a system. Surveys of public water systems, which havewent from a flat rate charge to individually metered services, have reduced system wideconsumption by as much as 50%. The usage rate generally will increase slightly with time after meters havebeen installed.

Flow. Flow requirements must be determined to insure the adequacy of the system to deliver the requiredamount of water on demand. The first step in calculating flow requirement is to estimate the average dailyconsumption, which is discussed above under the heading of “Usage”. The average daily consumption canthen be translated to a average instantaneous daily flow value, most often referred to as average demand oraverage flow, usually expressed in gallons per minute (gpm). The peak demand rate (peak flow) can then beestimated by multiplying the average flow by the appropriate correction factors. The peak flow requirementscan be ten times greater than the average daily flow. Knowledge of the average and peak flow requirementsin a system is critical for developing system infrastructure such as; pipe lines, pumping equipment, bufferstorage, treatment, etc.



Section 1


Pressure. For ordinary service, the typical delivery pressure ranges from 20 to 40 psi. The discharge pressure atthe well head (discharge of the pump) is often 10 to 20 psi greater than system pressure to over come frictionlosses within the system. Optimum system pressure requirements are a function of topography, fire protectionneeds, building height, etc. The availability of water under pressure stimulates its use. Increasing pressurefrom 25 psi to 45 psi can encourage a increase water use of up to 30%.

Storage. Storage is required to equalize pumping rates over the day, to equalize supply and demand over along period of high consumption, and to furnish water for such emergency and seasonal usage such as firefighting and landscape irrigation.

The issues discussed above under the general heading of “Quantity of Water” are most applicable to public watersystems. Technical issues associated with estimating usage, flow, pressure and storage requirements for several ofthe most common water system categories are detailed in Section 1D “Water System Capacity Requirements”. Specialconsiderations, such as landscape irrigation and fire protection are addressed within the context of each watersystem category (system type) presented in Section 1D.

Water Usage in the United States. On average, the United States uses 80 to 100 gallons of drinking water perperson per day. Of the “drinking water” supplied by public water systems, only a small portion is actually used fordrinking. A majority of residential water consumers use water for such purposes as: sanitation, cooking, cleaningand landscape irrigation.

The typical daily residential water use profile is described as follows:

• Lowest rate of use - 11:30 p.m. to 5:00 a.m.• Sharp rise/high use - 5:00 a.m. to noon. (Peak hourly use from 7:00 a.m. to 8:00 a.m.)• Moderate use - noon to 5:00 p.m. (Lull around 3:00 p.m.)• Increasing evening use - 5:00 p.m. to 11:00 p.m. (Second minor peak from 6:00 p.m. to 8:00 p.m.)

A typical family of four on a public water supply uses about 350 gpd. In contrast, a typical household that gets itswater from a private well or cistern uses about 200 gpd for a family of four. The commonly accepted value forindividual water usage for rural/domestic populations is 100 gpd per person. Public water systems typically used adesign values ranging from 125 to 175 gpd per person (175 gpd avg.) Major factors which affect consumption aremetering, climate and delivery pressure.

Commercial and industrial businesses may also place heavy demands on public water supplies. In most watersupply systems, the predominant number of user connections are residences, but the few connections tononresidential customers may account for a significant portion of the system-wide water use. Of the total annualU.S. water use; it is estimated 10% is consumed by residential use, with the remainder being consumed by Industryand Agriculture.

Rights to the Use of WaterThe right to use surface or groundwater for domestic use, irrigation, or other purposes varies between states. Somewater rights stem from ownership of the land bordering or overlying the source, while others are acquired by aperformance of certain acts required by law.

The three basic types of water rights are:

• Riparian - Rights that are acquired together with title to the land bordering or overlying the water source.• Appropriative - Rights that are acquired by following a specific legal procedure, usually involving diverting

unclaimed water and putting it to use.• Prescriptive - Rights that are acquired by diverting and putting to use, for a period, and under the conditions

specified by statute, water to which other parties may or may not have prior claims.

When there is any question regarding the right to the use of water, the utility owner should consult the appropriatestate authority and clearly establish the rights to its use.

1-7


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Section 1B Groundwater & Wells1-8

1B GROUNDWATER & WELLSGroundwater as a Water-Supply SourceRock Types and Geology. About 98% of the earth’s crust is composed of 8 chemical elements. Two of the eightelements, oxygen and silicon (silica Si 02), compose 75% of the crust. Most of the elements of the earth’s crust havecombined with one or more other elements form compounds called minerals. The minerals generally exist inmixtures to form rocks.

The rocks that form the earth’s crust are divided into three classes:

1. Igneous. Rocks that are derived from magma deep in the earth. They include granite and other coarselycrystalline rocks, dense igneous rocks such as basalt and other lava rocks occur in dikes and sills.

2. Sedimentary. Rocks that consist of chemical precipitates and rock fragments deposited by water, ice, or wind.These include deposits of gravel, sand, silt, clay, and the hardened derivatives of these-conglomerates, sandstone,siltstone, shale, limestone, gypsum and salt.

3. Metamorphic. Rocks that are derived from both igneous and sedimentary rocks through considerable alternationby heat and pressure at great depths. These include gneiss. schist, quartzite, slate, and marble.

The pores, joints, and crevices of the rocks in the zone of saturation are generally filled with water. Although theopenings in these rocks are usually small, the total amount of water that can be stored in the subsurface reservoirsof the rock formations is large. The most productive aquifers are deposits of clean, coarse sand and gravel; coarse,porous sand stone; cavernous limestone; and broken lava rock. Some limestone, however, is very dense andunproductive. Most of the igneous and metamorphic rocks are hard, dense, and of low permeability, and generallyyield small quantities of water. Among the most unproductive formations are the silts and clays. The openings inthese materials are too small to yield water, and the formations are structurally too weak to maintain large openingsunder pressure. Compact materials near the surface, with open joints similar to crevices in rock, may yield smallamounts of water.

Formation and deposition of the various rock types can be further classified in terms of geologic time period. Thetime period in which the various formation deposits were made often identify the characteristic of the groundwater(Aquifer) system. Generally, younger rocks are better aquifer’s than older materials.

Groundwater and Quality. Water movement within a ground water basin is caused by gradient changes. Gradientchanges are primarily a result of recharge (inflow), stemming from precipitation infiltration and discharge (outflow)as a result of pumping. The quantity of water that can be removed from a ground water basin, without depletingstorage, is referred to as the basin yield.

Proper development of a groundwater source requires careful consideration of the hydrological and geologicalconditions of the area. Information about the geology and hydrology of an area may be available in publication ofthe US Geological Survey or from other federal and state agencies. The National Water Well Association may alsooffer assistance.

Sanitary Quality of Groundwater: When water seeps through overlying material to the water table, particles insuspension, including microrganisms, may be removed. The extent of removal depends on the thickness andcharacter of the overlying material. Clay or hardpan provides the most effective natural filtration of ground water.Silt and sand also provide good filtration if it is fine enough and in thick enough layers. The bacterial quality of thewater also improves during storage in the aquifer because storage conditions are usually unfavorable for bacterialsurvival.

Groundwater found in unconsolidated formations (sand, clay, and gravel) and protected by similar materials frompollution sources is more likely to be safer than water coming from consolidated formations (limestone, fracturedrock, lava, etc.).


Section 1

Section 1B Groundwater & Wells 1-9

In areas where human waste are deposited in septic tanks, cesspools, or pit privies, the bacteria in the liquideffluents from such installations may enter shallow aquifers. Sewage effluents have been known to enter directly intowater-bearing formations by way of abandoned wells or soil-absorption systems. In such areas, the threat ofcontamination may be reduced by proper well construction-locating the well father from the source of contamination.The direction of groundwater flow usually approximates that of surface flow, and it is always desirable to locate awell so that the normal movement of ground water flow carries the contaminate away from the well.

Chemical and Physical Quality of Groundwater. The mineral content of groundwater reflects the type offormation which it moves through. Generally, groundwater in arid regions is harder and more mineralized thanwater in regions of high annual rainfall. Deeper aquifers are more likely to contain higher concentrations ofminerals in solution because the water has had more time to dissolve the mineral rocks. For any groundwaterregion there is a depth below which salty water, or brine, is almost certain to be found. This depth varies from oneregion to another.

Some substances found naturally in groundwater, while not necessarily harmful, may cause a disagreeable taste orundesirable properties to the water. Magnesium sulfate (Epsom salt), sodium sulfate (Glauber’s salt), and sodiumchloride (common table salt) are a few of these. Iron and manganese are commonly found in groundwater. Regularusers of water containing relatively high concentrations of these substances commonly become accustomed to thewater and consider it good tasting.

Concentrations of chlorides and nitrates that are unusually high generally indicate sewage pollution.

Temperature. The temperature of groundwater remains nearly constant throughout the year. Water from veryshallow sources (less than 50 ft [15m] deep) may vary in temperature from one season to another, but water fromdeeper zones remain relatively constant – about the same as the average annual surface air temperature. Beyondabout 100 ft (30 m), the temperature of ground water increases steadily at the rate of about 1°F (5/9°C) for each 100ft. (30m) of depth. In volcanic regions, this rate of increase may be much greater.

Figure 1-4: Typical Groundwater Temperature in the U.S @ 100’ Depth


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Distances to Sources of Contamination. All groundwater sources should be located a safe distance from sourcesof contamination. In cases where sources are severely limited, groundwater that might become contaminated maybe considered for a water supply if treatment is provided. All water sources should be placed a safe distance frompotential contamination with consideration to the direction of water movement. A determination of a safe distanceshould be based on specific local factors and addressed in the “Sanitary Survey” phase. Table 1-1 is a guide fordetermining safe distances.


Table 1-1: Guide for Determining Location of Water Source From Contamination Source

Formation Minimum Acceptable distance from Well to Source of Contamination

Favorable 50 ft (15 m). Lesser distances only with health department approval following (unconsolidated) comprehensive sanitary survey of proposed site and immediate surroundings.

Unknown 50 ft (15 m) only after comprehensive geological survey of the site and its surroundings hasestablished, to the satisfaction of the health agency, that favorable formations do exist.

Poor Safe distances can be established only following both the comprehensive geological and (consolidated) comprehensive sanitary surveys. These surveys also permit determining the direction in

which a well may be located with respect to sources of contamination. In no case shouldthe acceptable distance be less than 50 ft (15 m)

Development of a Groundwater Supply. The type of groundwater development to be undertaken depends onthe geological formations and hydrological characteristics of the water-bearing formation. Development of groundwater falls into two main categories:

1. Development by wells 2. Development from springsa. Nonartesian or water table a. Gravityb. Artesian b. Artesian

Note: Development of springs is outside the scope of this manual.

Nonartesian wells penetrate formations in which groundwater is found under water table conditions. Pumping fromthe well withdrawls water, lowering the water table in the vicinity of the well, as a result of the artificially createdpressure differences.

Artesian wells penetrate aquifers in which the ground water is found under hydrostatic pressure. Such a conditionoccurs in an aquifer that is confined beneath an impermeable layer of material at an elevation lower than that of theintake area of the aquifer. When the water level in the well stands above the top of the aquifer, the well isdescribed as artesian. A well that yields water by artesian pressure at the ground surface is a flowing artesian well.

Preparation of Ground Surface at Well Site. A properly constructed well should prevent surface water from enteringa ground water source to the same degree as does the undisturbed overlying geologic formation. The top of thewell must be constructed so that no foreign matter or surface water can enter. The well site should be properlydrained and adequately protected against erosion, flooding, damage and contamination. Surface drainage should bediverted away from the well.

Well Yields. The amount of water that can be pumped from any well depends on the character of the aquifer andthe construction of the well. In general, doubling the diameter of a well increases its yield only about 10 percent.The casing diameter is generally selected to provide enough room for proper installation of the pump.

A more effective way of increasing well capacity is by drilling deeper into the aquifer. Consideration of the inletportion of the well structure (screen, perforations, slots) is also important in determining the yield of a well in asand or gravel formation. The amount of open area in the screened or perforated portion exposed to the aquifer iscritical. Wells completed in consolidated formations are usually of open-hole construction.


Section 1

Section 1B Groundwater & Wells

It is rarely possible to accurately predict the yield of a well before it is completed. Knowledge can be gained fromstudying the geology of the area and results obtained from other wells constructed in the vicinity. This informationis helpful in selecting the location and type of well most likely to be successful. The information can also providean indication of the yield to expect.

A common way to describe the yield of a well is to express its discharge capacity in relation to its drawdown. Thisrelationship is called the “specific capacity of the well” and is expressed in gallons per minute per foot ofdrawdown. The specific capacity may range from less than 1 gpm/ft of drawdown for a low yield well to several100 gpm/ft for high yield wells.

Groundwater Hydrology and Well HydraulicsPorosity. Not all of the water contained in unconsolidated sand and gravel aquifers (water-bearing formation) canbe used. The amount of water which can be taken out of an aquifer depends upon the porosity of this water-bearing formation.

Porosity is a termdescribing the amount ofopen space between sandgrains in an undergroundaquifer (Figure 1-5 -diagram A). The term“absolute porosity” is thetotal amount of water thatcan be held in a givenvolume of the aquifer. Ofthe total amount of waterheld in an aquifer, only aportion of it is “free water”available for use. It is thisfree water which can beused promptly, thatdetermines the useable

porosity of the formation. The useable “bound water” is trapped (held) in the form of a thin film wetting the sidesof the particles of sand (Figure 1-5 - diagram B). The more uniform the grains of sand are in size, the higher theporosity and yield from a well. A fine uniform sand will often produce more water than a coarse, mixed sand andgravel.

Permeability and Transmissibility.The terms permeability andtransmissibility are used to describe theability of an aquifer (or water bearingfomation) to allow water to pass throughit. The drawing in Figure 1-6 shows asand and gravel water bearing formationand the arrows indicate the water flow.Permeability is a measure of the flow ofwater, in gallons per day, which will takeplace across opposite faces of a one footcube (P) under a differential head of onefoot of water. Transmissibility is theaverage permeability of a section (T) ofthe entire aquifer at a given locationmultiplied by the thickness of theaquifer.

1-11

Figure 1-5: Porosity of a Water - Bearing Formation

Figure 1-6: Permeability and Transmissibility Illustration


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Cone of Depression. When a well is pumped, the water level in the well falls below the water level out in theaquifer, creating a gradient which immediately creates a flow into the well from all directions. As a result, the freewater surface in the aquifer takes the shape of an inverted cone or curved funnel. This cone is appropriately calledthe “cone of depression”.

If the material of the aquifer transmits water easily, the cone is flat and wide spread. If it transmits poorly, the conewill be steep. The cone does not have a fixed shape and becomes deeper and flatter as the well is pumped. Thescience of aquifer hydraulics has been built around the shape and behavior of this cone. Cone of depression issuesare graphically illustrated in Figure 1-13 - diagram A & B.

Seasonal Water Level Changes. A hydrograph is a record of water levels over a period of time. To obtain ahydrograph on ground water, a recorder is installed in an observation well which is not directly affected bypumping. The water level in the observation well fluctuates with the seasons of the year. Water levels will be fairlyconstant during the winter months and a sharp rise in the water level is generally noted in the spring season,followed by a slow decline through summer and fall. The range of seasonal variations may be as great as five to tenfeet and has a marked effect on the yield in shallow wells.

Hydrographs on artesian wells show interesting effects. Changes in barometric pressure may cause a foot or morechange in water level. Earthquake tremors temporarily affect levels and can be detected by sensitive hydrographinstrumentation. Pumping data obtained during the spring should be adjusted to allow for the normal decline inwater levels typically observed in the fall. The collection of such hydrographic data on local ground and surfacewater sources is often available form the Federal and State Geological Surveys.

Figure 1-7: Seasonal Water Level Changes

Well Efficiency and Overpumping. The concept of pumped well efficiency was first presented by Jacob in 1947.Basically, “well efficiency” is defined as the formation loss (the head loss required to produce flow) divided by thetotal drawdown observed in the well. This quotient is expressed as a percentage and is typically calculated basedon data compiled from a step - drawdown pump test.

Figure 1-8 represents a simplified sketch illustrating the well efficiency concept. Since groundwater flow throughporous medial is laminar in nature, the head loss required to produce the flow through the aquifer is directlyproportional (linear) to the well discharge.


Section 1


Construction and maintenance parameters to be considered in order to maximize well efficiency are:

1. Well screen aperture size (as large aspossible consistent with gravel packformation material retention).

2. Screen entrance velocity (3.5 fps or less,assuming at the design flow rate- 50%plugging of the available screen open area -effective area of opening).

3. Well development (well development shouldbe conducted immediately after completionand should be continued until there is nochange in specific capacity/well yield).

4. In areas where wells are subject to plugging,as a result of incrustation and/or fouling,chemical treatment should be performedperiodically to maintain acceptable wellperformance.

In general, open hole completions inconsolidated formations are more efficient than

screened completions in unconsolidated formations assuming complete development. High efficiency does notinsure higher specific capacity, as wells completed in unconsolidated formation usually have a higher specificcapacity than consolidated formations.

Overpumping (pumping the well in excess of the design rate) will result in decreased well efficiency. Adverseaffects associated with overpumping are:

• Increased risk of dry run (pump-off) and/or cascading water which may damage pumping equipment. • Increased risk of developing a sand problem, which can damage the well and pump.• Decrease in water quality as a result of adverse gradient changes (salt water intrusion, pull in of pollutants, silt

fouling, etc.)• Increase incrustation potential. Deep drawdown increases oxygen exposure (oxidation) and can lead to plugging

of both the well and pump. Incrustation is a function of the presence of detrimental micro-organisms and specificwater quality conditions.

Careful analysis of pumptest data should be madeto insure pumpingequipment is sizedproperly to avoidoverpumping. Pumping tostorage over a longerperiod of time and/or theconstruction of multiplewells to provide therequired system demandcan be used to reduce overpumping.

1-13

Figure 1-8: Well and Formation Loss in a Pumped Well

PumpingWaterLevel

Static Water Level

Well Loss

Formation Loss

Flow

Figure 1-9: Overpumping Illustration

0 100 200 300 400 500 600 700 800 900 1000 gpm

Static Water Level

Acceptable Gradient (ft/gpm)IncreasingGradient

40

10Acceptable Well Load

Overpumping

FormationLoss

55


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Well Spacing and Interference. The location of water wells in relation to one another becomes critical where:

1. The land is limited for large spacing between wells.2. There is a high concentration of wells in the immediate vicinity.3. A high yield well field is planned.4. The aquifer has a low permeability and/or nearby boundaries, or when recharge is at great distance.

When determining well spacing requirements, it is necessary to have some idea of the shape and extent of the“cone of influence”. The cone of influence is defined as the slope of the hydraulic gradient or water surface awayfrom a pumping well. Figure 1-13 diagram C illustrates “cone of influence” affect relative to well spacing. Bydetermining the “cone of influence” of adjacent wells the effect of the overlapping curves can be determined, and adecision made to allow a large overlap or keep the overlap small. The cone of influence is normally determined byan aquifer pumping test. This involves measuring flows and draw- downs in the pumping well and observationwells located a distance away from the pumping well. In some highly permeable formations, wells of 2000 gpmcapacity could be spaced 200’ apart, as opposed to a low permeability formation 50 gpm wells might be spaced upto 1000’ apart.

Groundwater Mining. Excessive pumping of an aquifer or water-bearing formation is called “groundwatermining”. Groundwater mining occurs when the quantity of water annually pumped out of a given aquifer exceedsthe quantity recharged into the aquifer. Prolong groundwater mining will result in a declining water tables and cancreate serious long term water supply problems, as well as increasing the cost of pumping. In certain areas, surfacesubsidence can occur as the water bearing formation is de-watered.

The overproduction (overdraft pumping) from a well can only be maintained until the water in storage has been“mined out”. Pumping level on the well will continue to fall until it reaches the bottom of the well, at which timeproduction cannot exceed the natural recharge rate. Overpumping and overdraft pumping are not directly relate;overpumping applies to exceeding the well design capacity, where as overdraft pumping refers to the long termdepletion of aquifer storage.

A remedy for groundwater mining is to space wells further apart to capture only the groundwater which is escapingfrom various water supply sources such as rivers, streams and lakes. In some areas, the deficiency is being made upby artificial recharge from surface water sources, as they become available. In arid regions such as the southwesternstates, where pumpage far exceeds available recharge, there is no easy solution short of reduced pumping from theaquifer.

Figure 1-10: Ground Water Mining

Flow

1970

1980

1990

(Water Level)

Clay


Section 1


Artificial Recharge. When the groundwater level in an area drops at an excessive rate, it is a sign thatgroundwater mining is occurring. In some cases it is possible to make up this shortage with surface water. If theaquifer is shallow, it may be possible to artificially recharge the aquifer by ponding or shallow recharge pits. If theaquifer is relatively deep and confined between with impervious materials, recharge wells may be required.

Artificial recharge is commonly practiced in many arid regions. Increased usage of this practice is recommended in areaswhere the groundwater supply is being depleted. Successful use of this method requires a careful study and analysis.

Figure 1-11: Artificial Recharge

Surface Water Recharge Ponding Well Water Supply

Sand & Gravel

Clay

Well

Dewatering. A dewatering system is typically used to lower (depress) water levels for the purposes of constructionof sub surface structures, changing aquifer flow gradient for the purposes pollutant recovery and to counterbuoyancy forces which can dislodge (float out) underground structures subjected to high water table.

Shallow Dewatering for construction purposes is typically accomplished through the insertion of 2” diameter wellpoints at depths and spacings ranging from 10’ - 25’ and 20’ - 25’ respectively. The well points are typicallyplumbed into a central collection header system, using a single large pump equipped with a auxiliary vacuumpump, to “dewater” each well through a riser pipe by suction lift.

Deep Dewatering (25’ and greater), generally require the use of individual pumps which must be controlled basedon water level within the well. Submersible pumps are typically used for this purposes, as they are ideally suited asa result of there compact design and high capacity. Control (water level maintenance) is accomplished using avariety of methods ranging from throttling valves, to on - off controls, to direct acting variable speed control or acombination of one or more of these techniques.

Figure 1-12: Typical Shallow Well Dewatering System

Note: Mutualinterference between 2 or morewells depresses thewater table fordewatering operations.

Water Well Hydraulics. When a well is pumped, the level of the water table in the vicinity of the well will belowered (Figure 1-13 A). This lowering, or drawdown, causes the water level to take the shape of an inverted conecalled a cone of depression. This cone, with the well at the apex, is measured in terms of the difference betweenthe static water level and the pumping level. At increasing distances from the well, drawdown decreases until theslope of the cone merges with the static water table. The distance from this point to the well is called the radius ofinfluence. The character of the aquifer-artesian or water table-and the physical characteristics of the formation thataffect the shape of the cone include thickness, lateral extent, size and grading of sand or gravel.

The radius of influence is not constant and continuously expands with continued pumping. At a given pumpingrate, the shape of the cone of depression depends on the characteristics of the water-bearing formation. Shallowwide cones will form in highly permeable aquifers composed of coarse sand or gravel. Steep and narrow cones willform in less permeable aquifer. As the pumping rate increases, the drawdown increases and consequently the slopeof the cone steepens. In a material of low permeability such as fine sand or sandy clay, the drawdown will begreater and the radius of influence less than for the same pumpage from very coarse gravel (Figure 1-13).

When the cones of depression overlap, the local water table will be lowered (Figure 1-13). An increase in pumpinglifts is required to obtain water from the interior portion of the group of wells. Wider distribution of wells over thegroundwater basin will reduce the cost of pumping and allow the development of more water.


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Figure 1-13: Pumping Effects on Aquifers

DischargeGround Surface

Static Water Table

Cone of Depression forLesser Pumping RateCone of Depression for

Greater Pumping Rate

Radius of Influence

Draw-Down

A. Effect of Pumpingon Cone ofDepression


Static Water Table

Cone of Depression

Radius of Influence

Fine Sand

Draw-Down


Static Water Table

Cone ofDepression

Radius of Influence

Coarse Gravel

Draw-Down

B. Effect of AquiferMaterial on Coneof Depression

DischargeB

Discharge

Aquifer

A

Cone created by pumping wells A and B

Cone created by pumping well AStatic Water TableC. Effect of

OverlappingField of InfluencePumped Wells


Section 1


Well Design & ConstructionWell Specifications. High capacity water wells are usually constructed by contract, so it is advisable that carefulspecifications be written to insure a satisfactory well. Before specifications are written there should be considerableinvestigation made by the system operator or owner. Some estimates and investigation should be made of the wellsize and capacity by way of the methods outlined in this manual.

The drilling of a test hole as part of the geophysical investigation process is recommended in order to specify inadvance the well completion requirements (casing, screen, gravel pack, etc.). In areas where high capacity waterwell completions are not always assured, a test well may be necessary – in addition to a test hole – to properlyassess the suitability of the well location. A sanitary survey investigation as described in Section 1C should beconducted in conjunction with the initial investigation. The contract technical specification for a production waterwell should address the following issues.

1. Design Targets. An estimate of the anticipated well capacity in gpm, depth and diameter must be established inorder to develop preliminary well design parameters, select drilling equipment and infrastructure planning.

2. Construction Method. The drilling and completion method should be specified based on the type of waterbearing formation in which the well completion is to be made.

3. Casing. The type, weight, material, diameter and wall thickness of the casing should be specified, as well asaccessory item requirements.

4. Screen. The screen type, diameter, wall thickness, aperture size, etc.

Note: Screen selection and installation intervals are normally based on geophysical investigative work performed in conjunction with test hole work,

5. Gravel Pack. Gradation and installation interval to be specified when applicable.

6. Annular Seals. Grout/cement mix and application interval to be specified.

7. Development & Testing. Development and testing criteria should be clearly specified. In general, developmentshould be continued until no increase in well specific capacity (yield) is noted and the sand specification ismet. Pump performance testing should be conducted for 8-72 hours (minimum of 8 hours) after development.

8. Sand Content. A typical sand specification for a new water well is: “sand content not to exceed 5 ppm (mg/ l),15 minutes after the start of pumping”. A properly designed and developed well should easily maintain thesand content level substantially below 1 ppm.

9. Alignment. In general, the well should not vary from the vertical (drift) in excess of 3” per 100’ of casing length(ie. 6” @ 200’ is permissible). Proper alignment of the well should be guaranteed and a test of alignmentrequired.

10. Sanitary. Sanitary requirements should be recognized by closing the top of the well so that no surface watercan enter. The casing of the well should extend at least 6” (150 mm) and preferably 12” (300 mm) above thefinished grade. In areas subject to flooding, the well casing should extent 24” (600 mm) above the 100 yearflood level. The well should be cleaned of all debris, lubricants and mud. Disinfection of the well must beperformed.

All documents and records to be maintained, and submitted by the contractor should be clearly specified in thecontract documents (logs, casing and screen materials, aperture size, gravel analysis, etc.). Reliable local contractorsand consultants can provide valuable advice and design assistance in the development of a water well supplysource. The American Water Well Association (AWWA) standard A100-84 for water wells, contains sample contractlanguage and various design aids.

Types of Wells. Wells are constructed using a variety of methods such as; dug, bored, driven, jetted or drilled.Table 1-2 summarizes the suitability of the various well construction methods for a specific application and geologicformation. High capacity water wells are typically drilled using either the percussion (cable tool) or rotary (direct orreverse) drilling technique and/or combination of both.

High Capacity Water Well Drilling Methods. As previously mentioned, the two most common methods of drillinghigh capacity water wells are the cable tool and rotary drilling techniques. These techniques, as they relate todrilling and completion (casing and screen) are presented below.

Cable Tool. In the cable tool (percussion) drilling method, the borehole is drilled by the pulverizing action ofa reciprocating steel bit suspended from the drilling rig by a wire cable. As the bit strikes the bottom of thehole, the formation is crushed, creating cuttings which are removed by balling. If the formation is loose andunconsolidated, the casing must be forced into the hole periodically to prevent caving.

Several procedures are available for completing wells drilled by the cable tool method. If casing is installed asthe hole is drilled, it may be perforated by down-the-hole tools, forming a screen opposite the water-producing formations. With most methods of down-the-hole perforating, a small aperture cannot be formednor can the aperture size be precisely controlled. Consequently, finer-grained aquifers must be avoided. Ingeneral practice, the cable tool method lends itself more to drilling coarser, harder formations. Cable tool welldiameters and depths range from 8” to 18” and 100’ to 1000’ respectively.

Small diameter wells for domestic purposes, drilled in tight - consolidated formations, can be constructedusing the cable tools or down-the-hole air hammers. These wells often only need a surface conductor casinginstalled through the unconsolidated over-burden. Water is produced from the open hole. In some cases, aprotective casing is installed to the depth of the pump.

Rotary. The use of the direct rotary and reverse circulation rotary drilling methods are the dominate methodof construction of higher capacity production water wells. Both rotary methods can be used to constructgravel envelope wells in unconsolidated formations. Typical rotary drilled well completions in unconsolidatedand consolidated formations are illustrated in Figure 1-14.

Direct Rotary. In the direct rotary method, a rotating bit under controlled loading is applied to the formation.Drilling fluid (water with additives-mud, is used to provide weight and viscosity) is pumped down the drillpipe, through the bit, and circulates up the hole carrying the cuttings, which are separated and removed at thesurface. Usually the finished borehole is drilled in two or more stages. A smaller pilot bore is drilled first, thenreamed to a diameter 6 to 12 inches greater than that of the casing and screen. The screen is selected anddesigned according to information gained through analysis of the cuttings, formation and electric logs.

The casing string (blank pipe & screen) is generally installed in a continuous operation. Selected gravel isplaced in the annular space adjacent to the screen, between the casing and enlarged hole to stabilize theformation and provide a filter against fine sand or silt. The annular space between the borehole and blankfilled with cement grout. Well diameters and depths range form 4” to 24” and 100’ to 3000’ respectively.

Reverse Rotary. The reverse circulation rotary method varies from the direct rotary method in three majorrespects. The circulating fluid flows down the hole and up the drill pipe. Drilling fluid hydrostatic pressureagainst the formation maintains the wall of the borehole from caving both systems, usually no additives aremixed with the circulating water (drilling fluid). The reverse circulation procedures, the hole is normallydrilled in one pass without staging. Well completion (blank casing, screen, gravel placement and grout) areinstalled in the same manner as the direct rotary process.

Equipment requirements differ in that drill pipe diameters range from 6” to 10” and a high capacity suction liftpump is normally used to create the “reverse” flow. A compressor is required for deep well applications toinduce reverse flow via air lift pumping action. The reverse rotary method is particularly applicable tounconsolidated formations, where large diameter-high capacity well construction is required. Well diametersand depths generally range from 18” to 42” and 100’ to 1500’ respectively.


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Section 1


Air Rotary. The air rotary method is similar to the rotary hydraulic method in that the same type of drillingmachine and tools may be used. The principal difference is that air rather than mud or water is used as thedrilling fluid. In place of the conventional mud pump to circulate the fluids, air compressors are used.

The air rotary method is best suited for consolidated formation, and is especially popular in regions wherelimestone is the principle water source. The air rotary method requires that air be supplied at pressures from100-250 psi. To effect removal of the cuttings, rising velocities of at least 3000 fpm are necessary. Penetrationrates of 20-30 fph in hard rock are common with air rotary methods.

Table 1-2: Suitability of Well Construction Methods to Different Geological Conditions

Characteristics Dug Bored Driven Jetted

Range of practical depths 0-50 ft. 0-100 ft. 0-50 ft. 0-100 ft.(general order of magnitude) (0-15 m) (0-30 m) (0-15 m) (0-30 m)

Diameter 3-20 ft. 2-30 in. 1 1/4-2 in. 2-12 in.(1-6 m) (51-762 mm) (32-51 mm) (51-305 mm)

Type of geologic formation:

Clay Yes Yes Yes Yes

Silt Yes Yes Yes Yes

Sand Yes Yes Yes Yes

Gravel Yes Yes Fine 1/4-in (6-mm)pea gravel

Cemented gravel Yes No No No

Boulders Yes Yes, if less than No Nowell diameter

Sandstone Yes, if soft Yes, if soft Thin layers only No

Limestone and/or fractured and/or fractured No No

Dense igneous rock No No No No

Drilled

Rotary

Characteristics Percussion Direct Reverse Air

Range of practical depths 0-1000 ft. 0-3000 ft. 0-1500 ft. 0-750 ft.(general order of magnitude) (0-305 m) (0-610 m) (0-455 m) (0-229 m)

Diameter 4-18 in. 4-24 in. 18-42 in. 4-10 in.(102-457 mm) 102-610 mm) (305-762 mm) (102-254 mm)

Type of geologic formation:

Clay Yes Yes Yes No

Silt Yes Yes Yes No

Sand Yes Yes Yes No

Gravel Yes Yes Yes No

Cemented gravel Yes Yes (Difficult) No

Boulders Yes, when in (Difficult) (Difficult) Nofirm bedding

Sandstone Yes Yes No Yes

Limestone Yes Yes No Yes

Dense igneous rock Yes Yes No Yes

Note: The range of values in this table are based upon general conditions.

Drilling Method Selection Factors. Many factors are considered in selection of drilling method and well design.Among them are depth, diameter, hardness of formation, presence of fine-grained aquifers that need a gravelenvelope filter, accessibility of site to equipment and availability of the quantity of water required for drilling. Rotarydrilling construction - particularly reverse rotary, requires large amounts of water. In some areas, gravel envelopewells permit the production of greater quantities of water than non-gravel envelope wells, but this is not always thecase. Many high efficiency water wells are being constructed today by the cable tool method.

The diameter of a well should be selected only after a careful consideration of all factors such as the desired yield;the type of well construction; the type of pumping equipment to be used; the physical character of the waterbearing formation; etc. The ability to produce sand-free water from water-bearing sands is related to the diameter ofthe well. A larger well diameter coupled with screen open area will decrease the velocity of the water as it entersthe well. Decreased velocity reduces the possibility of pumping fine sand.

Sanitary Construction of Wells. Although there are different types of wells and construction methods, there arebasic sanitary aspects that apply to all. The broad issues are described as follows:

• The annular space outside the casing should be filled with a watertight cement grout or suitable impermeablematerial form the surface to the deepest level of excavation or as deep as necessary to prevent entry ofcontaminated water, whether from surface runoff or other aquifers.

• For artensian aquifer, the casing should be sealed into the overlying impermeable formations so as to retain theartesian pressure.

• When a water-bearing formation containing water of poor quality is penetrated, the formation should be sealedoff to prevent infiltration of water into the well and aquifer.


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Figure 1-14: Typical Rotary Drilled Well Completions

Discharge

Sanitary Well Seal

Connection toSource of Power

PlugAir VentGround Surface

Sloped to DrainAway from Well

Top Soil

Artesian Pressure Surfaceor Piezometer Surface

Clay

Cement GroutFormation Seal

Dynamic (Pumping)Water Level

Submersible Pump

Taper SectionScreen

Water Bearing Sand

A. Unconsolidated Formation

Outer Casing

Drill Hole Diameterfor Cemented Casing

Cement Grout

Inner Casing

Drill HoleThrough Soft Formation

CavingFormationCased Out

Pumping UnitMaximum Dia.

Open Hole

Hole Diameteron Bottom

B. Consolidated Formation


Section 1


• A sanitary well seal with an approved vent should be installed at the top of the well casing to prevent entrance ofcontaminated water or other objectionable material. The well seal should be installed per the appropriateregulatory requirements. A pitless adapter and cap assembly should be used in situation where applicable.

For large-diameter shallow wells, it is difficult to provide a sanitary well seal to the depth normally required bymost regulatory authorities. A typical surface completion consisting of a reinforced concrete slab, overlapping thecasing and sealed to it with a flexible sealant or rubber gasket are normally used to affect a sanitary seal. Theannular space between the casing and bore hole should first be filled with suitable grouting or sealing materialsbefore surface completion.

Well Completion Considerations. The well size and completion method depends upon four principal issues:

1. The type of water bearing formation.a. Consolidated formations - limestones, sandstones, granites, etc.b. Unconsolidated formations - alluvial, glacial, sand and gravel deposits, etc.

2. The permeability of the water bearing formation. (The ability of the formation to yield water).3. Design capacity of the well.4. The type of deep well pump to be utilized. High capacity submersible pumps may require a larger diameter than

turbine pumps to facilitate power cable installation; although alignment may be less critical.

Type of water bearing formationa. Wells drilled into consolidated formation are normally more expensive and deeper than shallow

unconsolidated wells, the diameter is normally kept as small as possible in line with the diameter of pump tobe used. Normally, a minimum of 2” is allowed between the pump end/ bowl and the casing, and 3”between the casing and borehole.

b. In unconsolidated formations, the screen diameter may depend upon the bowl /pump diameter but may beincreased to:1. Reduce the entrance velocity through the screen.2. Increase the screen opening area for longer life if mineral deposition from the ground water is a problem.3. A minimum of 8” is added to the screen diameter for the gravel wall diameter (4” annulus). A 12” increase

(6” annulus) is recommended; however, larger annular clearance may improve well performance.Note: Typical guidelines for screen and gravel pack selection are overviewed in Section 1B.

Permeability of the FormationIncreasing the well borehole diameter in a consolidated formation will increase the yield somewhat, dependingon how many additional crevices are encountered by the increased diameter. In unconsolidated formations it isoften wise to increase the well diameter in formations with low permeability so that the maximum flow can beobtained. The higher the permeability the less the well diameter will increase the specific capacity (well yield).

Design CapacityLocal knowledge from existing well completions, local hydrology and geology studies can be used to estimate wellyield and estimate pump size. The pump chamber casing diameter can be determined by estimating the maximumpump unit diameter (based on well yield) by adding at least 2” the minimum pump diameter, 3” is recommendedfor ease of installation of submersible units casing diameter vs pump/motor size are listed in Table 1-4.

Downhole Logs and Geophysical Investigative Methods. Numerous instruments and techniques are available forspecial investigations of sub-surface and groundwater conditions. Logging equipment can be lowered into a well viawireline, measurements and other data are recorded at the surface by electrical means. Several of the mostcommonly used logging techniques used in the water supply industry are presented as follows:

1. Electric log: (single point, short normal - 16” and long normal - 64”): Used in uncased fluid filled boreholes andare typically used for; identification of lithologic (sand, clay, etc.), determine high and low permeability zones,and casing depth in cased hole applications

2. Caliper log: Measures hole diameter at any depth; useful to locate large casing breaks, determine of size andposition of casing and liners, location of caving formations (shales, cavernous limestone, etc.), determination ofthe effectiveness of “shooting” for well development and/or enlarging diameter, etc.

3. Temperature log: Measures water temperature at any depth; useful in locating sources of flow into the well,casing leaks, etc.

4. Fluid Velocity log: Measures flow (natural or artificial) at any point in hole-either up or down; useful indetermining contributing permeable and “thief” zones, casing leaks, etc.

5. Radiation log: Similar in use to electric logging, but can be used in cased well or open hole. Radio- active logsare generally source collecting and measure the natural radioactivity of the fomation material. They are extremelyuseful where formation materials are known to have higher natural radioactivity compared to others (ie. claysare often more radioactive than sands in certain geologic areas).

6. Water Sampler: Permits collection of water samples for analysis from any depth in the well.7. Video log: Video logs are predominately used to identify the location of casing imperfections (breaks), screen

damage or verification of prominent features at the proper depth.

Other geophysical methods, such as surface seismic and electrical resistively surveys, have been successfully used inmany areas to map the bedrock surface in order to identify sub-surface water-bearing sand or gravel. Such surveysdo not replace a program of test drilling, but merely serve to aid in selecting the most favorable sites for test holesand/or wells. These special geophysical investigative method are normally conducted in area where geology ishighly variable and well productivity is highly variable.

Logs and Samples. In drilling any well, regardless of the method used (i.e. cable tool, rotary, etc.) the driller shouldkeep an accurate formation log and completion records. The logs and records should include: the location of thewell; name of owner; owner’s well number; total depth of borehole, casing and screen; borehole size; elevation atthe surface (if known); depth, thickness, and character of each type of formation material penetrated (lithologicinformation); depth (s) at which water was encountered - if possible; depth to water level upon completion of thewell; the date the well was started and completed. The state or regulatory agency having regulatory jurisdiction willrequire a driller report be filed. The driller report will generally require the above minimum information.

Well production data (flow rate, draw-down, water levels, etc.), as well a final pump installation data if known,should be complied. In the construction of high capacity water wells, the drilling and pump contractor may bedifferent, making record collection difficult if not specifically identified by contract. Such records are invaluable asthey are required for proper pump sizing and future system expansion-particularly if additional wells are to bedrilled nearby or if the well requires any repair or reconditioning.

Actual formation and geophysical logs (electric logs, etc.) are usually much more valuable than the written log keptby the driller, both samples and logs should be kept for analysis and maintained until all regulatory reports are filedand/or contractual data is provided to the owner or its agent.

In unconsolidated formations, where a gravel pack well completion is to be made, representative formation samplesin the water bearing zone, collected during the drilling process are often analyzed. The purpose of the analysis is todetermine formation grain size distribution via sieve analysis. The grain size distribution of water bearing formationis key factor in gravel pack selection and/ or screen aperture size selection.

Water Well Casing and Pipe. There are several kinds of steel pipe suitable for casing drilled wells. The commonlytypes are; standard pipe, line pipe, drive pipe, reamed and drifted (R&D) pipe, and water-well casing. Steelpossesses high strength and resiliency required for water well service, and is weldable. There are certain differencesin size, wall thickness, type of connection and method of manufacture. Well casing must meet certain generallyaccepted specification for quality of steel and wall thickness. Both are important because they determine resistanceto corrosion and consequently the useful life of the well. Strength of the casing may also be important indetermining whether certain well-construction procedures may be successfully carried out, particularly in cable-tooldrilling where hard driving of the casing is sometimes required.

The most commonly accepted specifications for water well casing are those prepared by the American Society forTesting and Materials (ASTM), American Petroleum Institute (API), and the American Iron and Steel Institute (AISI).

Table 1-3 lists the minimum acceptable wall thickness requirements for carbon steel water well casing based ondiameter and depth. If conditions are known to be corrosive; consideration should be given to corrosion resistantmaterial such as stainless steel, plastic, fiberglass or the use of greater wall thickness carbon steel pipe. PVC plasticcasings should be made of a material approved for use with potable water by the National Sanitation Foundation (NSF).


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Section 1


Refer to Section 7A for a overview of the various tubular products used in the water supply industry.

Well Casing Diameter vs. Pump Size. The diameter of the upper pump housing casing must provide sufficientclearance between the largest pump component diameter and the casing. In addition to accommodating the obviouspump and motor dimensional requirements, a clearance allowance must be made for power cable and a water levelmeasurement device.

No well is exactly “straight” (perpendicular to ground level) and operation will be unsatisfactory if there is severemisalignment. In addition, consideration should be given to the possibility of corrosion product buildup which maylock the pump to the casing. It is recommended that pump housing casing should have a minimum diameter atleast two inches greater than the nominal diameter of the largest pump component (ie. pump, motor or columnpipe collar) required for desired yield.

Table 1-4 and 1-5 can be used as a guideline for determining the minimum casing size for a given flow, pumpdiameter or speed.

Table 1-3: Suggested Minimum Thickness for Carbon Steel Water Well Casing

Casing Diameter (in.)

6 8 10 12 14 16 18 20 22 24 30

0-100 12 12 12 10 10 8 8 8 8 8 3/16

100-200 12 12 10 8 8 8 3/16 3/16 3/16 3/16 1/4

200-300 10 10 8 8 8 3/16 3/16 3/16 1/4 1/4 1/4

300-400 10 8 8 3/16 3/16 3/16 1/4 1/4 1/4 1/4 5/16

400-600 10 8 3/16 3/16 3/16 1/4 1/4 1/4 5/16 5/16 5/16

600-800 3/16 3/16 3/16 3/16 1/4 1/4 1/4 5/16 5/16 3/8 3/8

800 + 3/16 3/16 3/16 1/4 1/4 1/4 5/16 5/16 3/8 3/8 7/16

Casing Depth(ft.)

Note: 1. Diameter thickness in U.S standard gauge or fraction of a inch.2. A minimum of 1/4” wall thickness is normally specified for high capacity water well for municapal

purposes.

Table 1-4: Casing Diameter vs. Well Capacity and Pump Diameter

Q (gpm) Minimum Casing Recommended Casing *Pump/ Motor

Dia. (in.) Dia. (in.) Dia.(in.)

0 to 25 4 ID 6 ID >4

0 to 100 6 ID 8 ID 4

100 to 300 8 ID 10 ID 6

300 to 700 10 ID 12 ID 8

700 to 1400 12 ID 14 OD 10

1400 to 2000 14 OD 16 OD 12

2000 to 3000 16 OD 18 OD 14

3000 to 4500 18 OD 20 OD 16

* Pump, motor or column pipe coupling diameter whichever is larger.


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Table 1-5: Casing Diameter vs. Well Capacity & Pump Operating Speed

Nominal Pump Nominal Op. Capacity/Yield Minimum Casing Recommended CasingDiameter (in.) Speed (rpm) (gpm) Dia. (in.) Dia. (in.)

2 ** - 0 - 10 2 3

3 ** 3600 2 - 25 3 4

4 * 3600 5 - 75 4 6

6 * 3600 50 - 350 6 81800 100 - 200

7 3600 100 - 500 8 101800 50 - 275

8 3600 200 - 1200 10 121800 150 - 6001200 100 - 400

10 3600 500 - 1800 12 141800 200 - 15001200 370 - 670

12 3600 600 - 2500 14 161800 400 - 23001200 250 - 1500

14 1800 1000 - 4500 16 181200 800 - 3500

16 1800 2000 - 5200 18 201200 1300 - 3400

18 1800 3200 - 5400 20 241200 2200 - 4000900 2800 - 3000

Note: (1) For non-domestic submersible applications, it is recommended that the well inside diameter (I.D) be aminimum of 2” larger than the largest submersible component.

(2) For pump settings in excess of 400 feet, the minimum well ID should be increased to the next largerstandard size when practical.

* Domestic sized pumps and motors are typically 1” smaller than the casing I.D.** Special use submersible pumps or shallow well suction lift pumps

Well Casing Accessories. In addition to the casing and screen, high capacity water wells completed in sand andgravel formations using the rotary drilling method will often employ special components to enhance thecompletion. Several of the most commonly employed casing accessories are: (1) welding collars, (2) carbon steel tostainless steel change over connector, (3) compression section, (4) casing guides, (5) float plates and (6) taper(reducer reduction) section.

1. Welding Collars are factory installed to one end of each casing or screen joint to facilitate quick casinginstallation by reducing set-up, welding and alignment time. Lap welded collared joints provide a strongerconnection than butt welded joints.

2. Carbon Steel to Stainless Steel Change Over Connectors are used reduce the rate of galvanic corrosion betweendissimilar metals, which can occur when stainless steel well screen is joined to carbon steel blank casing.Change over connectors range from insulated couplings to special slip weld connections, where there is nodirect weldment between the stainless steel and carbon steel material. The slip weld connection relies on theformation of a oxide layer on the carbon steel surfaces where it contacts stainless steel to inhibit corrosion. If


Section 1


stainless steel is welded directly to carbon steel, the carbon steel section should be at least two times thethickness of the stainless.

3. Compression Sections are often used in areas prone to subsidence as a result of groundwater mining, and inearthquake prone regions. The compression section provide a casing stress relief point should the groundsurface drop in the immediate vicinity of the well head.

4. Casing Guides are used primarily to center screen within the borehole. In water well applications, guides aretypically attached by welding and are placed at forty foot intervals. Three to four guides are used at each intervaland are placed equidistantly around the screen. Guides are not typically used with blank casing, unless specialcementing (grouting) requirements are specified.

5. Float Plates are installed in the casing, where the weight of the casing (screen and blank casing) exceed the safelifting capacity of the drill rig. The float plate allows for buoyancy forces to counter the weight of the casing as itis installed. The weight of the casing is reduced by the weight of the fluid displaced. Fluid is added to the casingafter each successive connection to force the casing down. When the casing operation is completed the floatplate, is removed by impact (striking) with drill pipe or bailer. Float plates are typically constructed of cast iron,which has high strength but low impact resistance.

6. Taper Sections are used to provide a smooth transition from casing and/or screen of different diameters. Longtransition (3 - 4 ft.) fabricated diameter reductions are preferable to abrupt changes in diameter from aconstruction and maintenance stand point.

Gravel Pack. The gravel filter pack envelope well serves two vital purposes; (1) stabilizes the casing (blank casingand screen) between the boreholes by filling the annular space and (2) provides a graded filter for the fine grainedparticles in the aquifer. Neither purpose can be achieved if the gravel pack is not placed in a continuos and uniformmanner in the annulus. Formation analyses associated with the gravel pack and screen aperture size selectionprocess are discussed in greater detailed later in Section 1B.

Gravel pack selection based solely on formation sampling can be misleading as it assumes formation samples aretruly representative of the aquifer. Strict adherence to good formation sampling collection and analysis proceduresare required where no historic data is available. In well established groundwater basins, field experience and pastapplications can be used to supplement analytical techniques.

Grouting (Annular Seal). The penetration of a water bearing formation by a well provides a direct route forpossible contamination of groundwater. This space must be filled with grout to prevent surface contaminants fromrunning down the annulus and into the aquifer. A properly installed grout seal reduces the possibility ofcontamination.

Sealing the annulus in the non-producing formation zones has other advantages, in addition to sealing out poorquality water from an overlying aquifer; it increases the life of the well by protecting the casing against exteriorcorrosion; and it stabilizes the soil and rock formation to help prevent caving.

Water Well Screen. Screens or slotted casings are installed in wells to permit sand-free water to flow into the welland to provide support for unstable formations to prevent caving. In a drilled well, the screens are normally placedafter or at the same time the casing is installed. In a driven well, the screen is a part of the drive assembly and issunk to its final position as the well is driven.

The size of the slot (aperture) for the screen or perforated pipe should be based on a sieve analysis of selectedsamples from the water-bearing formation that is to be developed or gravel packed. The analysis is usually made bythe screen manufacturer or contractor. If the slot size is too large, the well may yield sand when pumped. If the slotsize is too small, it may become plugged with fine material, and the well yield will be reduced. Common types ofmanufactured screen include; milled slot, wire wrap, bridge slot and shutter screen. Slots cut with a down hole millknife or holes burned into the bottom end of the casing string should not be substituted for a manufactured wellscreen.

The relationship between screen open area and entrance velocity of water through the openings should beconsidered if maximum hydraulic efficiency is desired. Loss of energy in the form of incereased draw down andformation material transport is kept to a minimum by holding velocities between 0.1 fps and 0.5 fps. These lowentrance values are often unobtainable and as a practical matter, velocities up to 3.5 fps have been employedwithout appreciable loss in well efficiency or transport of formation material, in properly designed gravel packwells.

Since slot size is determined by grain size distribution in the aquifer sand or gravel pack, the required open areamust be obtained by varying the diameter or, if aquifer thickness permits, by varying the length of the screen.Manufacturers of well screens provide tables of capacities and other information to facilitate selection of the mosteconomical screen dimensions.

A screen is seldom required in wells that tap bedrock fractures or tightly cemented sediments such as sand stone orlimestone.

Well Screen Diameter Considerations. Well screen diameter does not have much effect on production water yield;however, there are strong reasons for specifying identical casing and screen diameters (with the exceptions oftelescoped screen installations and under-reamed gravel envelope well designs). Equal internal diameters facilitatewell development, redevelopment and provide options should special conditions such as formation gas,incrustation, corrosion or sand become a issue. The possibility of damage due to dropping a pump or tools isminimized. Maintaining identical diameters reduces head loss through the screen and improves well efficiency. Wellssmaller than six inch diameter are difficult to repair and larger diameter wells are easier to deepen where wellconstruction and formation condition make such practices possible.

In wells deeper than 1,200 feet, a reduction of four inches in screen diameter can be practical. This is generallylimited to high capacity wells where the screen diameter is a minimum of 12 inches. The saving in screen andborehole costs may offset other considerations. This reduction normally begins at the bottom of the pump housingcasing.

Formation Analysis - Gravel Pack and Screen Aperture Selection. Evaluation of representative formationsamples (sand in the interval to be screened) is performed to determine screen aperture (slot) size. The twoprincipal forms of high capacity water well completions in unconsolidated water bearing sands are “gravel pack”and “naturally developed”.

(1) In a gravel pack completion, the well diameter in the vicinity of the screen is typically 12” larger than the screenand graded gravel is used as a filter media to prevent sand pumpage. The screen aperture is sized to retain amajority of the gravel pack.

(2) In a naturally developed well completion, the well is drilled no larger than required to insert the screen andcasing. The screen aperture is sized to retain a majority of the natural formation material. Filler gravel is sometimesused to fill void space between the borehole/casing string annulus.

A complete course in well design and gravel pack selection is outside the scope of this manual; however, generalscreen aperture size selection criteria and related information are presented in the following figures and tables.


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Section 1


Table 1-6: General Screen Aperture (slot) Size Selection Criteria

Naturally Developed Wells

Step 1) Obtained samples representative of formation materials

Step 2) Perform formation grain-size (sieve) analysis

Step 3) Select slot size that retains > 70% of formation materials

Gravel Packed Wells

Step 1) Obtain samples representative of formation materials

Step 2) Perform formation grain-size (sieve) analysis

Step 3) Select filter medium (sand) based on 70% retained formation grain size multiplied by:

• 3 if formation is fine and uniform, or• 6 if formation is coarse and non-uniform

(uniformity coefficient of filter medium should be less than 2.5)

Note: Gravel pack selection is sometimes based on maintaining a Grave Pack Ratio (GPR = 50% gravel packsize/50% formation size) of 5 to 7. The gravel pack distribution should parallel the formation distribution.

Step 4) Select a slot size that retains 95 - 100% of filter pack materials

Note: Uniformity Coefficient = Grain Size Retained @ 40%/Grain Size Retained @ 90%

Table 1-7: Common Screen Aperture (slot) Size Selection Practices vs Filter Pack/ Grain Size

Aperture Size Media Distribution

in. mm U.S. Sieve Size Range

0.006 (0.15) 50 - 100

0.010 (0.25) 20 - 40

0.020 (0.50) 12 - 20

0.030 (0.75) 12 - 20

0.040 (1.0) 8 - 12

0.060 (1.5) 6 - 9

0.080 (2.0) 4 - 8

Figure 1-15: Typical (% Retained) Grain Size Distribution

10 20 30 40 50 60 70 80 90 100

GRAIN SIZE, THOUSANDTHS OF AN INCH

100

80

60

40

20

0

CU

MU

LA

TIV

E %

RE

TAIN

ED Grain Size Distribution

% Retained


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Table 1-8: Physical Properties of Water Bearing Sand and Gravel Formation Materials

Sieve Standard Sieve Opening Transport Velocity

Tyler Standard U.S. Standard Opening Opening Lifting SettlingSieves Sieves (Inches) (Microns) (fps) (fph)

– – .250 6350 Medium Gravel – –

4 4 .187 4699 2.75 –

6 6 .131 3327 – –

8 8 .093 2362 – –

9 10 .078 200 Fine Gravel 0.58 –

10 12 .065 1651 – –

12 14 .055 1400 – –

14 16 .047 1180 –

16 18 .039 1000 Coarse Sand 0.35 1181

20 20 .0328 850 – –

24 25 .0276 710 – –

28 30 .0234 600 – –

32 35 .0195 500 Medium Sand 0.25 626

35 40 .0164 425 – 496

48 50 .0116 295 – 378

60 60 .098 250 Fine Sand – –

65 70 .0082 210 – 248

80 80 .069 175 – –

100 100 .0058 147 – 177

150 140 .0041 105 Silt & Clay 0.10 94

200 200 .0029 74 – 71

250 230 .0024 62 – 45

– – – 20 – 7

Note: (1) microns = mm x 1000, (2) fps = ft./ sec., (3) fph = ft./ hr.(4) AWWA Material Classification by Grain Size• Gravel 0.080” (2.032 mm)• Very coarse sand 0.040” - 0.080” (1.016 - 2.032 mm)• Coarse sand 0.020” - 0.040” (0.508 - 1.016 mm)• Medium sand 0.010” - 0.020” (0.254 - 0.508 mm)• Fine sand 0.005” - 0.010” (0.127 - 0.254 mm)• Very fine sand 0.003” - 0.005” (0.076 0.127 mm)• Silt and clay < 0.003” (< 0.076 mm)

Grain SizeClassification

(USGS Method)

Well Development. Developing the well is necessary to obtain its maximum capacity for a given drawdown. Thedeveloping process usually uses hydraulic agitation to remove the fine material from the formation near the wellcasing perforations, thereby opening up passages so that the water can enter the well more freely. Typical methodsused for well development include but are not limited to; air lift pumping, swabbing - via surge block and testpumping. All three methods agitate and surge the water-bearing strata adjacent to the well screen, which washesout the fine material from the formation.

The method of development must be suited to the aquifer and the type of well construction. Proper development isnecessary to maximize well yield and remove formation materials that might otherwise damage production pumpingequipment or plug the well. Well development is required/recommended after completing most drilling and wellconstruction processes.


Section 1


Sand Content. Issues associated with sand content concentration levels are discussed in Section 2D, under theheading of “Entrained Solids (Sandy Water)”. In general, the sand content of a new and fully developed water wellshould not exceed 5 mg/l, 15 minutes after start-up.

Performance Testing. After the well is developed, a long term pump (yield) test is normally conducted on thewell using a test pump. Depending on the formation and historical data, the duration of a long term pump test atthe design flow rate can range from 8 to 72 hours. The pump test should be conducted until the pumping waterlevel remains stable and/or as required by contract. It is important that the test pump be accurately sized for thewell in order to obtain the best test results. The test pump should have variable speed capability, with 10 - 50%greater capacity and lift than anticipated at full load speed. Test data should include the static water level (standingwater level), pumping water level, discharge rate, water level, sand content, recovery measurements and duration.

Long term pump test data can be used for aquifer analysis in conjunction with water level recovery data. Waterlevel recovery (residual drawdown) measurements can provide significant aquifer information and typically rangefrom 1 - 24 hours. A step drawdown test is sometimes performed at several flow rates to develop a wellperformance curve for the purposes of determining well efficiency. Pump test data is used to select the productionpumping equipment for the intended application, and should be corrected for seasonal variations as applicable.Failure of the well to recover completely to the original static water level within the same time period as the pumptest, is an indication of aquifer storage depletion.

Well Alignment - Pump Setting Limits. The Bureau of Reclamation recommends that all casing to the lowestcontemplated pump setting should not deviate for vertical more than 3 inches per 100 ft. for casings up to 6 inchesdiam., 4 inches per 100 ft. for casing 8 to 12 inches diam., and 6 inches per 100 ft. for casing 14 to 18 inches diam.All casings up to 20 inches diam. should be sufficiently straight to permit free passage of a 40 ft. length of pipe withcouplings at each end and in the middle, of the next smaller size than can enter the well casing.

The AWWA recommends that the outer diameter of the plumb or dummy should not be more than 1/2 inch smallerthan the diameter of the part of the casing or hole being tested. The dummy is recommended to consist or a rigidspindle with 3 rings each 12 inches wide and truly cylindrical. If the dummy fails to move freely throughout thelength of the casing or hole to the lowest anticipated bowl setting, or should the well vary from vertical in excess of2/3 of the smallest diameter of that part of the well being tested per 100 ft. of depth, it is not satisfactory.

Impact of alignment deviation on pump installation are:

• A drift of 3” per 100 ft. of well depth is of little or on consequence.• A drift of 3 to 6” per 100 ft. of well depth is less desirable but not serious if the well is straight.• A drift of more than 6” per 100 ft. of depth may be extremely troublesome unless the pump is much smaller than

the well casing.

Note: A” dog-leg” in the well is a problem regardless of alignment drift.

Plumbness and Alignment Survey. AWWA standard A100 - 97 provides a procedure for conducting a Plumbnessand Alignment (deviation) survey. The purposes of such a survey is to graphically depict well alignment, as well asidentification of dog-legs which can make a well unusable depending on the location and surverity. The alignmentsurvey procedure is addreviated as follows:

Test Fixture Set-up. Using the test fixture as shown in Figure 1-16. The horizontal center of the pulley “C”should be exactly 10 feet above the top of the well. The vertical center of the pulley must be so located thatthe plumb line “A” will come off its outer edge exactly over the center “D” of the well casing. Unless thispoint is closely established the well survey will not be corrected.

The plumb ring “E” should be 1/4” smaller than the inside diameter of the well casing and should be heavyenough to keep the plumb line taut. The ring must not be solid as the water must pass through it as it islowered in the well. The hole “F” through which the plumb line “A” passes must be in the exact center of thering. Marks should be made every 10 feet on the plumb line, to indicate the depth the ring has been loweredin the well.

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Drift Calculation Procedures. Well drift characteristics are determined by lowering the plumb ring 10 feet at atime and taking a reading at each 10’ interval. If the plumb line passes exactly through the center line “D” at anylocation, the well is plumb at the depth the plumb ring is suspended. If the line “A” does not pass through “D”, thewell at that depth is out of plumb by the distance “A” varies from “D” plus an equal distance for each 10 feet thatthe plumb ring “E” is below the reference datum level.

Example 1-1: Well Alignment - Drift Calculation.

Assume that “c” is exactly 10’ above the reference datum and “D” is at datum level. (1) If plumb line “A”varies 1/16 of an inch form the center of the well at “D” and the plumb ring “E” is 10 feet below the referenceline, then the well is 1/8 out of plumb at the 10 foot level. (2) If “A” varies 1/16 inch form the center of thewell “D” when the plumb ring “E” is 50 feet below the datum at “D”, then the well is 1/16 plus 5/16 or 3/8 ofan inch out of plumb at the 50 foot level. The amount of drift is related to the proportional relationship ofsimilar triangles, and is illustrated as follows:

60 ft. x 1 = 3

10 ft. 16 8

Drift calculations at the various depths tested may be plotted on graph paper for a graphical depiction ofalignment. Typical forms of plumbness and alignment presentation are illustrated in Figure 1-17 and 1-18.


Figure 1-16: Alignment Survey Text Fixture

"E"

PlumbRing "E"

Exact Center"F"

PlumbLine"A"

Frame "B"

ExactWell

Center"D"

GuidePulley

"C"

Datum

Knots Every10 ft.

10'0"

Figure 1-17: Typical Alignment SurveyLongitudinal Projections


Section 1


Table 1-9: Typical Plumbness and Alignment Test Data Sheet

North South East West North South East West

10 .01 0 0 .02 0 0

20 .10 .01 .03 .03

30 .01 .015 .04 .06

40 .01 .015 .05 .075

50 .01 .015 .06 .09

60 .005 .015 .35 .105

70 .005 .015 .04 .12

80 .005 .02 .045 .18

90 .005 .02 .05 .20

100 .005 .02 .055 .22

110 .005 .01 .06 .12

120 .005 .01 .065 .13

130 0 0 .005 0 0 .07

140 .005 0 0 .075 0 0

150 .01 0 0 .16 0 0

160 .01 .005 .17 .085

170 .01 .005 .18 .09

180 .01 .01 .19 .19

190 .01 .01 .20 .20

200 .01 .01 .21 .21

Depth ofPlummet

Below Topof Well (ft)

Horizontal Deflectionof Plumb Line (ft)

Calculated Driftof Well (ft)

Well No. 1 Date: 3-21-75

Size of Hole or Casing = 19-1/4 in., ID Size of Plummet = 18-1/4 in. OD.

Height of Apex Above Top of Well = 10.0 ft.

Figure 1-18: Graphical Representation of Plumbness Requirements

.20 ft

.10 ft

.10 ft

.20 ft

.20 ft .10 ft .10 ft .20 ftEastWest

South

North

ImaginaryVertical Line

Depth 200 ft

Depth 100 ft

.23 ft = 2.75 in.

.30

ft =

3.63

in.

Depth Actual Drift Allowed Drift*

ft. in. in.

100 2.75 12.83

200 3.63 25.66

Drift is greatest at depths 100 ft. and 200 ft.

*For 19.250 in. ID casing.

Note that thiswell meets thespecificationsfor plumbness.


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Well Covers and Surface Seals. Every well should be provided with an overlapping, tight-fitting cover at the topof the casing or pipe sleeve to prevent contaminated water or other material from entering the well.

The sanitary well seal for a well exposed to possible flooding should be either watertight or elevated at least 2 ft.(0.6 m) above the highest known flood level. When it is expected that a well seal may become flooded, it shouldbe watertight and equipped with a vent line that has an opening to the atmosphere at least 2 ft. (0.6 m) above thehighest known flood level. Under normal circumstances, the minimum height or vent is usually specified by theregulatory agency having jurisdiction for public water supplies.

The seal in a well not exposed to possible flooding should be either watertight (with an approved vent line) or self-draining (non-watertight) type, all openings in the cover should be either watertight or flanged upward andprovided with overlapping, downward flanged covers. All sanitary well seals, pitless adapter units, and caps mustbe approved by local or state health departments.

Pumps should have a supporting base that can be effectively adapted to seal the upper terminal of the well casing.There are several acceptable sanitary well seal designs for submersible pumps consisting of an expandableneoprene gasket compressed between two steel plates (Figures 1-19 and 1-20), which are easily installed andremoved for well servicing. If the pump is not installed immediately after well completion, the top of the casingshould be closed with a metal cap screwed or tack-welded into place, or covered with a sanitary well seal.

A well slab alone is not an effective sanitary defense and alone, may not be permissible for public water supplypurposes. A cement grout formation seal is far more effective. Concrete slab or floor around the well casing tofacilitate cleaning and improve appearance should be placed only after the formation seal and/or the pitless installationhave been inspected. Well covers and pump platforms should be elevated above the adjacent finished ground level.Pump room floors should be constructed of reinforced, watertight concrete, and carefully leveled or sloped away fromthe well so that surface and wastewater cannot stand near the well. The minimum thickness of such a slab or floorshould be 4 in. (100 mm). Concrete slabs or floors should be poured separately from the formation seal.

All water wells should be readily accessible at the top for inspection, servicing, and unobstructed access for well-servicing equipment.


Figure 1-19: Typical Large Submersible Pump (LSP) Discharge Styles & Surface Plate Assemblies

Notes:1. Well seal surface plates are

for use where a sanitary wellsealing is required; a flangemust be welded to the casingby a continuous watertightweld or the plate must begrouted in place. Ordinarysurface plates may be usedwhere sanitary well seals arenot required.

2. The surface dischargeassembly must physicallycomply and be installed inaccordance with state orfederal sanitary requirementshaving jurisdiction. Vent wellas required for service and/orsanitary requirements.


Section 1


Abandoning Wells. Unsealed, abandoned wells constitute a potential hazard to the public health and welfare ofthe surrounding area. Sealing an abandoned well presents certain problems, and the solution involves considerationof well construction and the geological and hydrological conditions of the area. Factors to be considered whensealing an abandoned well are elimination of any physical hazard, prevention of any possible contamination ofgroundwater, conservation and maintenance of the yield and hydrostatic pressure of the aquifer, and prevention ofcontact between desirable and undesirable waters.

When a well is to be permanently abandoned, the well should be filled with concrete, cement grout, neat cement,or clays with sealing properties similar to those of cement in accordance with the regulatory agency havingjurisdiction. Care should be taken to insure sealing material does not bridge during installation. It is recommendedthat the top of the casing be cut-off five feet below the finished grade after the well is filled with impermeablematerial.

Well Failure. Over a period of time, wells may fail to produce for any of the following reasons:

• Failure or wear of the pump.• Declining water levels.• Plugged or corroded screens.• Accumulation of sand or sediments in the well.

Proper analysis of the cause necessitates measuring the water level before, during, and after pumping. To facilitatemeasuring the water level, an entrance for a tape or wire line electrical measuring device into the well in theannular space between the well casing and the pump column should be provided. A perminately installed airline orsubmersible water level transducer are often used to measure water levels and is recommended for applicationsrequiring frequent measurements or where it is difficult to insert portable devices. The airline method is notgenerally as accurate as the tape, electric wire line or the pressure transducer method.

If the well is completed as a pitless-adapter installation, consideration should be given as to how water levelmeasurement can be taken.

1-33

Figure 1-20: Typical Submersible Pump (Small Submersible) Discharge and Well Seal Completion

PowerCable

Bolt

Well Cap

Casing

ConcreteBase

Basket

Access Plug(Threaded)

Drop Pipe

Pipe Plug

Discharge Line

SubmersiblePump Cable

Drop Pipe fromSubmersiblePump

WireMesh

WellVent


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Any work performed within the well including insertion of a measuring line could potentially contaminate the waterwith coliform bacteria and other organisms. Care should be exercised when procuring water level measurements.All access holes should be tightly plugged or covered following the work.

Special Considerations in Constructing Artesian Wells. To conserve water and ensure good productivity froman artesian well, it is essential that the well casing be sealed into the confining stratum. Otherwise, water loss mayoccur by leakage into lower-pressure, permeable strata at higher elevations. A flowing artesian well should bedesigned so that the movement of water from the aquifer can be controlled. Water can be conserved if such a wellis equipped with a valve or shut off device.

In general, water can not be extracted from a flowing artesian well via pumping, greater than the natural flow.

Well Disinfection and TreatmentDisinfection of Wells. All newly constructed wells should be disinfected to eliminate contamination fromequipment, material, or surface drainage introduced during construction. Every well should be disinfected promptlyafter construction or repair.

An effective and economical method of disinfecting wells is use of calcium hypochlorite containing approximately70% available chlorine. This chemical can be purchased in granular or tablet form at hardware stores, swimmingpool-equipment outlets, or chemical supply houses. When used to disinfect wells, calcium hypochlorite should beadded in sufficient amounts to provide a dosage of approximately 50 mg/L of available chlorine in the well water.

When calcium hypochlorite is not available, other sources of available chlorine-sodium hypochlorite (12-15% ofvolume) can be used. Sodium hypochlorite, which is also commonly available as liquid household bleach with 5.25%available chlorine. Table 1-10 shows quantities of disinfectants to be used in treating wells of different diameters.


Table 1-10: Chlorine Compound Required to Dose 100 feet (30 meters) of Water-Filled Casing at 50 mg/l

Chlorine Compounds

Diameter of (70%) Calcium (25%) Chloride (12%) Sodium (5.25%) Sodium

Casing Hypochlorite 2/ of Lime Hypochlorite Hypochlorite

in. (mm) (Dry Weight) (Dry Weight) (Liquid Measure) (Liquid Measure)

2 (50) 1/4 oz (7 g) 1/2 oz (14 g) 1 1/2 oz (44 ml) 2 oz (59 ml)

4 (100) 1 oz (28 g) 2 oz (57 g) 7.8 oz (233 ml) 9 oz (266 ml)

6 (150) 2 oz (57 g) 4 oz (113 g) 13.9 oz (.4 l) 20 oz (0.6 l)

8 (200) 3 oz (85 g) 7 oz (0.2 kg) 1.4 pt (.7 l) 2 1/8 pt (1.0 l)

10 (250) 4 oz (113 g) 11 oz (0.3 kg) 2.0 pt (1 l) 3 1/2 pt (1.7 l)

12 (300) 6 oz (0.2 kg) 1 lb (0.45 kg) 3 1/2 pt (1.7 l) 5 pt (2.4 l)

16 (400) 10 oz (0.3 kg) 2 lb (0.9 kg) 2/3 gal (2.7 l) 1 gal (3.8 l)

20 (510) 1 lb (0.45 kg) 3 lb (1.4 kg) 1.0 gal (3.8 l) 1 2/3 gal (6.3 l)

24 (610) 1 1/2 lb (0.7 kg) 4 lb (1.8 kg) 11/2 gal (4.7 l) 2 1/3 gal (8.8 l)

Note: 1. Some authorities recommend a minimum concentration of 100 mg/l. To obtain 100 mg/l concentrationlevel, double the amounts shown in the table above.

2. 70% Calcium Hypochlorite tablets (ie. HTH, Perchloron, Pittchlor, etc.)3. Where dry chlorine is used, it should be mixed with water to form a chlorine solution prior to placing it

into the well. Dry chlorine should always be added to water - not vice versa, and should be addedslowly. These precautions are necessary to lessen the possibility of a violent chemical reaction.

4. 5.25% Sodium Hypochlorite solution - household bleach (ie. Chlorox, Purex, etc.)5. 12% Sodium Hypochlorite solution - commercial bleach.


Section 1


General Well Disinfection Practices. The chlorine solution should remain in the well for at least 4 hours, preferablelonger. After disinfection, the well should be pumped to waste, until the odor of chlorine can no longer be noticed.The well should then be tested for bacteriological quality to determine the chlorine’s effectiveness. In the case ofdeep wells having a high water level, it may be necessary to use special methods of introducing the disinfectingagent into the well, so as to ensure proper diffusion of chlorine throughout the well.

Flowing Artesian Wells. The water from flowing artesian wells is generally free from contamination after it is allowedto flow a short time. It is not generally necessary to disinfect flowing wells; however, should it become necessary todisinfect a flowing artesian well, chlorine solution should be placed at the bottom of the well and the well shut-infor 24 hours.

Bacteriological Tests Following Disinfection. The water from the system should not be used for domestic andcooking purposes until the results of the tests indicate that the water is safe for such uses. If bacteriologicalexamination of water samples collected after disinfection indicates that the water is not safe for use, disinfectionshould be repeated until tests show that water samples from that portion of the system being disinfected aresatisfactory. Samples collected immediately after disinfection may not be representative of the water used. Samplingis recommended (may be required) to be repeated several days after disinfection to verify the water delivered undernormal conditions of operation, meet the bacteriological requirements of the National Drinking Water Regulations.

Water Well Treatment. In water wells, decline in production basically is caused by:

1. Lowered static water level - depletion.2. Worn, corroded or debri plugged pump parts.3. Incrustation and micro - organism growths.4. Mud, sand and silt fouling.

Well treatment is effective only in the latter two types of situations.

General. Water quality is the key indicator as to the incrustation potential of a groundwater source (see Table1-8). The kinds and amounts of dissolved minerals and gases in groundwater determine its tendency either tocorrode or to deposit mineral matter as incrustation. When the groundwater formation is penetrated by a welland exposed to changing conditions (ie. oxygen introduced, pressure/velocity changes, etc.), the naturalbalance is changed. The change in local aquifer conditions coupled with water quality conducive to theformation of mineral deposits, can lead to well and/or pump plugging.

The four primary causes of plugging, in order of frequency of occurrence are: (1) incrustation fromprecipitation of carbonates of calcium and magnesium or their sulfates; (2) incrustation from precipitation ofiron and manganese compounds, primarily their hydroxides or hydrated oxides; (3) stoppage due to slimeproduced by iron bacteria or other slime-forming organisms; (4) stoppage resulting from deposition of soilmaterials, such as silt and clay, carried up to the well screen in suspension.

Guide to Chemical Treatment Methods. It is impossible to prescribe a method of well treatment that isapplicable to every well condition. Hence the methods prescribed should be tailored to provide the optimumtreatment for a specific well. Study of the well log, well record, and water analysis are often of value.

The majority of chemical treatments are made with the pump in the well. If the pump is removed, variationsin the application of the selected treatment method may be required to remove treatment spoils. Air-liftpumping for removal of the expended (spent) treatment solution, debris and associated dissolved materials iscommonly used in the absence of a pump.

Treating Solutions. Any chemical used in the treatment of a water well must be non-toxic and not impart ataste or odor to the water supply. The concentration of the treating solution is of the utmost importance. Asolution that is too weak will not be effective. One that is too strong will displace or dissolve more materialthan can be carried by the spent chemical solution. Heavy gels or flocculent precipitates with pluggingproperties may result.

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No one chemical solution is a cure-all. The type of chemicals, volume, concentration, and method of treatmentmust be selected carefully for optimum results. Several of the most common well/pump treatment methods,based on the plugging mechanism identified are briefly described as follows:

1. Chlorine Treatment. The chlorine solution is applied to the well and/or pumping equipment for sterilizationand for the destruction of plugging micro-organism (bacteria and slime) growth.

2. Acidizing Treatment. Acidizing of wells and pumping equipment serves to dissolve carbonate, manganese,magnesium, and iron encrustations; and for the specific destruction of specific micro-organisms. It is alsoused in the development process for enlarging the pores of limestone formations, and in some cases can beused to loosen stuck drilling tools in and soluble rock formation. Acid treatments should be used inconjunction with a inhibitor to reduce corrosive attack on metal components.

If zinc or magnesium anodes are used in the pump for cathodic protection, the anodes or the pump mustbe removed from the well prior to any acid treatment. No galvanized pipe or fittings should be used in theacid treatment. The acid quickly reacts with and dissolves the zinc or magnesium, inhibited or notgenerating gaseous hydrogen.

3. Phosphate Treatment. Phosphates are primarily used as a treatment for mud and silt fouling, and rely on thedispersive - detergent effect of the phosphate solution. Phosphates are sometimes used in the developmentprocess to remove excessive drilling mud. Phosphate treatments generally require mechanical surging witha surge block to be affective, which requires pump removal. A improper phosphate treatment can beextremely detrimental to the water bearing formation, and will further reduce yield.

4. Explosive Treatment. Explosive treatment “shooting” is primarily used as a well development tool forincreasing the yield in tight consolidated sand stone formations. Explosives are rarely used for incrustationtreatment purposes.

5. Dry Ice Treatment. Compressed carbon dioxide gas, or dry ice, has been used to some extent in welldevelopment. Its efficiency is about equal to the air lift development process. It is an inexpensive andconvenient method of agitating and obtaining some back-pressure effect. It does not dissolve incrustations.

In areas where well and pump plugging is a possibility or a known problem, specific well performanceshould be monitored on a periodic or continuous basis. Flow, drawdown and kWh/1000 gal. (energy) datacan be used to establish well/pump cleaning and service intervals. Continuous monitoring instrumentation,such as the Grundfos CU3 control unit, are available for such purposes.

Maintaining well efficiency through the prevention of water level decline from plugging, as a result ofincrustation or fouling is extremely important. Energy costs to pump can be many times the initial cost of thepumping equipment over the service life, making good well maintenance a key factor in overall systemreliability and efficiency.



Section 1

Section 1C Water Quality & Treatment 1-37

1C WATER QUALITY & TREATMENTDrinking Water RegulationSafe Drinking Water Act (SDWA). In 1974, the US congress passed the Safe Drinking Water Act (SDWA, Public law93-523) establishing a cooperative program among local, state, and federal agencies to help ensure safe drinkingwater in the United States. Under the SDWA, the primary role of the federal government is to develop nationaldrinking water regulations that will protect public health and welfare. The states are assigned the responsibility ofimplementing the regulations and monitoring the performance of public water systems. The public water systemsthemselves are responsible for treating and testing drinking water to ensure that its quality consistently meets thestandards set by the regulations.

As directed by the SDWA, the U.S. Environmental Protection Agency (USEPA) developed primary and secondarydrinking water regulations designed to protect public health and welfare. The National Primary Drinking WaterRegulations (NPDWR) cover contaminants that have adverse effects on human health. These regulations are mostenforced by the State or the USEPA.

The Secondary Drinking Water Regulations cover contaminants that adversely affect the aesthetic quality of drinkingwater, such as taste odor, and appearance. Contaminants covered by Secondary Regulations do not normally affecthealth directly. There regulations are intended as guidelines and are not enforceable by USEPA; however, individualstates may choose to enforce some or all of the Secondary Regulations. Refer to Table 1-15 for a listing of thesecondary standard as applied to a typical ground water supply.

National Primary Drinking Water Regulations. The NPDWR are the drinking water regulations that apply to allpublic water systems in the United States. In order to provide adequate public health the SDWA makes it clear thatthe owners and operators of public water systems are responsible for ensuring that their systems meet theregulations. To help fulfill this responsible for ensuring that their systems meet the regulations. The SDWA andNPDWR address, five principal areas:

• Definition of “public water system”• Maximum contaminant levels (MCLs)• Sampling frequencies• Record-keeping requirements• Regulatory reporting requirements

The discussion refers only to the USEPA regulations; individual states can adopt more stringent regulations. Moststates have “primacy” responsibility under the SDWA with respect to enforcement of regulations and are responsiblefor their enforcement. A water supplier need only check with the appropriate state agency to learn exactly whatregulations apply to the water system.

Public Water System. A Public Water System (supply) is defined in the SDWA as those systems that either (1) have15 or more service connections or (2) regularly serve an average of 25 or more people daily for at least 60 dayseach year. The NPDWR applies to all public water systems.

There are two types of public water systems defined by the NPDWR: Community systems and non-communitysystems. A community system is one that serves a residential (year-round) population. A non-community system isone that serves intermittent users, such as a campground. Since certain contaminants have adverse health effectsonly when consumed regularly over a long period of time, the distinction between community and non-communitysystems is important in determining which contaminants must be monitored to protect public health.

As of 1998, there are approximately 59,000 community water systems in the U.S.

Maximum Contaminant Levels and Health Effects. Under the SDWA regulations, the USEPA has issued waterstandards for drinking an established maximum Contaminant Levels (MCLs) for more than 80 contaminants. Thestandard limit the amount of each substance allowed to be present in drinking water. A process called riskassessment is used to set drinking water quality standards. In developing drinking water standards, USEPA assumesthat the average adult drinks 2 liters of water each day throughout a 70-year life span.


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Risks are estimated separately for cancer and non-cancer effects. For cancer effects, a risk assessment estimates ameasure of the chances that someone may get cancer because they have been exposed to a drinking contaminant.USEPA generally sets MCLs at levels that will limit an individual’s risk of cancer from that contaminant to between 1in 10,000 and 1 in 1,000,000 over a lifetime. For non-cancer effects, the risk assessment estimates an exposure levelbelow which no adverse effects are expected to occur.

MCLs are set based on known or anticipated adverse human health effects, the ability of various technologies toremove the contaminant, their effects, the ability of various technologies to remove the contaminant, theireffectiveness, and cost of treatment. All MCL’s are set at levels that protect public health. The limit for manysubstances is based on lifetime exposure so, for most potential contaminants, short-term exceedances pose a limitedhealth risk. The exceptions are the standards for coliform bacteria and nitrate, for which exceedances can pose animmediate threat to health. Table 1-12 lists the MCL’s specified in the NPDWR for various contaminants, therepotential health effects and typical source of contamination.

Public water purveyors will often report water supply quality data periodically as general mineral, general physical,inorganic & organtic chemicals (pesticides and volatile organics). Table 1-11 lists a typical summary presentation ofgeneral mineral, general physical and organic constituents. Table 1-11 lists a typical summary presentation oforganic contaminants, radioactivity and microbiology quality.

Monitoring & Reporting Requirements. To ensure that drinking water meets the standards set by the SDWA. USEPAhas established pollutant specific minimum testing schedules for public water systems. Table 1-11 shows the majorgroups of contaminants and the minimum frequency that public water systems must test. If a problem is detected,there are immediate retesting requirements that go into effect and strict instructions for how the system informs thepublic about the problem. Until the system can reliably demonstrate that it is free of problems, the retesting iscontinued. Refer to the appropriate water quality regulatory agency having jurisdiction for reporting requirements.

Section 1C Water Quality & Treatment1-38

Table 1-11: Typical Monitoring Schedule

Contaminant Minimum Monitoring Frequency

Acute Contaminants

Bacteria Monthly or quarterly, depending on system size and type

Protozoa and Viruses Monthly monitoring for turbidity and total coliforms, as indicators

Nitrate Annually

Chronic Contaminants

Volatile Organics Ground water systems, annually for 2 consecutive years; surface water systems annually(e.g., benzene)

Synthetic Organics Larger systems, twice in 3 years; smaller systems, once in 3 years(e.g., pesticides)

Inorganics/Metals Ground water systems once every 3 years; surface water systems, annually

Lead and Copper Annually

Radionuclides Once every 4 year

Note: General requirements may differ slightly based on the size or type of drinking water system.Source: USEPA - A consumer’s guide to the Nation’s Drinking Water


Section 1

Section 1C Water Quality & Treatment

Record keeping. The SDWA requires record keeping for compliance. In addition to the compliance requirement,records are useful in evaluating system performance, planning improvements and writing reports. Records must bemaintained and stored for specific time periods, as established by the NPDWR. Storage periods range from 3 to 10years pending record type and category.

Regulatory Reporting Requirements. To ensure that prompt attention is given to potential health problems, theNPDWR require water systems to submit routine reports to the appropriate regulatory agency. The regulatoryagency is most often the State; however in some states the USEPA has primary responsibility for implementing theSDWA.

There are three types of reports that must be sent to the state (regulatory agency):

• Routine sample reports • Check sample reports • Violation reports

Refer to the appropriate water quality regulatory agency for sampling, report frequency and MCL violation reporting.

Public Notification. Public Notification is a requirement of the SDWA which requires water suppliers to notify theircustomers when their system is in violation of the NPDWR. The purpose of the notice is to protect consumers fromwater that may be temporarily unsafe, as well as to increase public awareness of the problems water systems faceand the costs of supplying safe drinking water. Violation notification by mail is sufficient for all cases exceptviolation of an MCL, which requires newspaper and broadcast notice as well.

Refer to the appropriate water quality regulatory agency for specific public notification requirements of violations.

1-39


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Table 1-12: National Primary Drinking Water Standards

Contaminants MCLG MCL Potential Health Effects Sources of Contaminant in (mg/L) (mg/L) from Ingestion of Water Drinking Water

Fluoride 4.0 4.0 Skeletal & Dental Fluorosis Nat.l deposits; fertilizer, aluminum industries; wateradditive

Volatile Organics

Benzene 0 0.005 Cancer Some foods; gas, drugs, pesticide; paint, plastic industriesCarbon Tetrachloride 0 0.005 Cancer Solvents and their degradation process

p-Dichlorobenzene 0.075 0.075 Cancer Room and water deodorants, and “mothballs”1,2-Dichlorobenzene 0 0.005 Cancer Leaded gasoline, fumigants, paints1,1- Dichlorobenzene 0.007 0.007 Cancer Plastics, dyes, perfumes, paints

Trichloroethylene 0 0.005 Cancer Textiles, adhesives and metal degreasers1,1,1-Trichloroethane 0.2 0.2 Liver, nervous system effects Adhesives, aerosols, textiles, paints, inks, metal

degreasersMay leach from PVC pipe; formed by solvent break down

Vinyl Chloride 0 0.002 Cancer

Coliform & Surface Water Treatment

Giardia Lamblia 0 TT Gastroenteric disease Human and animal fecal wasteLegionella N/A TT Legionnaire’s disease Natural waters; can grow in water heating system

Standard Plate Count N/A TT Indicates water quality, effectiveness of treatmentTotal Coliform* 0 <5%+ indicates gastroenteric pathogens Human and animal fecal wasteTurbidity N/A TT Interferes with disinfection, filtration Soil runoff

Viruses 0 TT Gastroenteric disease Human and animal fecal waste

Inorganics

Antimony 0 0.006 Cancer Fire retardants, ceramics, electronics, fireworks, solderAsbestos (>10um) 7MFL 7MFL Cancer Natural deposits; asbestos cement in water systems

Barium* 2 2 Circulatory system effects Natural deposits; pigments, epoxy sealants, spent coalBeryllium 0.004 0.004 Bone, lung damage Electrical, aerospace, defence industriesCadmium* 0.005 0.005 Kidney effects Galvanized pipe corrosion: natural deposits, batteries,

paint

Chromium* (total) 0.1 0.1 Liver, kidney, circulatory disorders Natural deposits; mining, electroplating, pigmentsCyanide 0.2 0.2 Thyroid, nervous system damage Electroplating, steel, plastics, mining, fertilizerMercury* (inorganic) 0.002 0.002 Kidney, nervous system disorders Crop runoff, natural deposits, batteries, electrical switches

Nitrate* 10 10 Methemoglobulinemia Animal waste, fertilizer, natural deposits, septic tanks,sewage

Nitrite 1 1 Methemoglobulinemia Same as nitrate; rapidly converted to nitrateSelenium* 0.05 0.05 Liver damage Natural deposits; mining, smelting, coal/oil combustion

Thallium 0.0005 0.002 Kidney, liver, brain, intestinal Electronics, drugs, alloys, glass

Organics

Acrylamide 0 TT Cancer, nervous system effects Polymers used in sewage/wastewater treatmentAdipate 0.4 0.4 Decreased body weight Synthetic rubber, food packaging, cosmeticsAlachlor 0 0.002 Cancer Runoff from herbicide on corn, soybeans, other crops

Atrazine 0.003 0.003 Mammary gland tumors Runoff from use as herbicide on corn and non-croplandCarbofuran 0.04 0.04 Nervous, reproductive system effects Soil fumigant on corn and cotton; restricted in some areasChlordane* 0 0.002 Cancer Leaching from soil treatment for termites

Chlorobenzene 0.1 0.1 Nervous system and liver effects Waste solvent from metal degreasing processesDalapon 0.2 0.2 Liver and kidney effects Herbicide on orchards, beans, coffee, lawns,

road/railwaysDibromochloropropane 0 0.0002 Cancer Soil fumigant on soybeans, cotton, pineapple, orchards

Dichlorobenzene 0.6 0.6 Liver, kidney, blood cell damage Paints, engine cleaning compounds, dyes, chemicalwastes

1,2-Dichloroethylene 0.07 0.07 Liver, kidney, nervous, circulatory Waste industrial extraction solventstrans-1,2 Dichloroethylene 0.1 0.1 Liver, kidney, nervous, circulatory Waste industrial extraction solventsDichloromethane 0 0.005 Cancer Paint stripper, metal degreaser, propellant, extraction

1,2-Dichloropropane 0 0.005 Liver, kidney effects, cancer Soil fumigant; waste industrial solventsDinoseb 0.007 0.007 Thyroid, reproductive organ damage Runoff of herbicide from crop and non-crop applicationsDioxin 0 3EE-8 Cancer Chemical production by-product, impurity in herbicides


Section 1


Table 1-12: National Primary Drinking Water Standards (continued)

Contaminants MCLG MCL Potential Health Effects Sources of Contaminant in (mg/L) (mg/L) from Ingestion of Water Drinking Water

Diquat 0.02 0.02 Liver, kidney, eye effects Runoff of herbicide on land & aquatic weeds2,4-D 0.07 0.07 Liver and kidney damage Runoff from herbicide on wheat, corn, rangeland, lawnsEndothall 0.1 0.1 Liver, kidney, gastrointestinal Herbicides on crops, land/aquatic weeds; rapidly

degraded

Endrin 0.002 0.002 Liver, kidney, heart damage Pesticide on insects, rodents, birds, restricted since 1980Epichlorohydrin 0 TT Cancer Water treatment chemicals, waste epoxy resins, coatingsEthylbenzene 0.7 0.7 Liver, kidney, nervous system Gasoline, insecticides, chemical manufacturing wastes

Ethylene Dibromide 0 0.00005 Cancer Leaded gasoline additives, leaching of soil fumigantGlyphosate 0.7 0.7 Liver, kidney damage Herbicide on grasses, weeds, brushHeptachlor 0 0.0004 Cancer Leaching of insecticides for termites, very few crops

Heptachlor Epoxide 0 0.0002 Cancer Biodegration of heptachlorHexachlorobenzene 0 0.001 Cancer Pesticide production waste by-productHexachloro-cyclopentadiene 0.05 0.05 Kidney, stomach damage Pesticide production intermediate

Lindane 0.0002 0.0002 Liver, kidney, nerve, immune, circ. Insecticide on cattle, lumber, gardens, restricted 1983Methoxchlor 0.04 0.04 Growth, liver, kidney, nerve effects Insecticide for fruits, vegetables, alfalfa, livestock, petsOxamyl (Vydate) 0.2 0.2 Kidney damage Insecticide on apples, potatoes, tomatoes

PAHs (Benzo(a)pyrene) 0 0.0002 Cancer Coal tar coatings, burning org. matter, volcanos, fossil fuelPCBs 0 0.0005 Cancer Coolant oils from electrical transformers, plasticizersPentachlorophenol 0 0.001 Liver and kidney effects, cancer Wood preservatives, herbacide, cooling tower wastes

Phthalate (di(2-ethylexyl)) 0 0.006 Cancer PVC and other plasticsPicloram 0.5 0.5 Kidney, liver damage Herbicide on broadleaf and woody plantsSimazine 0.004 0.004 Cancer Herbicide on grass sod, some crops, aquatic algae

Styrene 0.1 0.1 Liver, nervous system damage Plastics, rubber, resin, drug ind., leachate from landfillsTetrachloroethylene 0 0.005 Cancer Improper disposal of dry cleaning & other solventsToluene 1 1 Liver, kidney, nervous, circ. Gasoline additive, manufacturing and solvent operations

Toxaphene 0 0.003 Cancer Insecticide on cattle, cotton, soybeans, cancelled 19822,4,5 - TP 0.05 0.05 Liver and kidney damage Herbicide on crops, golf courses, cancelled 19831,2,4 - Trichlorobenzene 0.07 0.07 Liver and kidney damage Herbicide production, dye carrier

1,1,2 - Trichloroethane 0.003 0.005 Kidney, liver, nervous system Solvent in rubber, organic products, chemical prod.wastes

Xylenes (total) 10 10 Liver, kidney, nervous system By-product of gasoline refining, paints, inks, detergents

Lead and Copper

Lead* 0 TT+ Kidneys, nervous system damage Natural/industrial deposits, plumbiing, solder, brassCopper 1.3 TT# Gastrointestinal irritation Natural/industrial deposits, wood preservatives, plumbing

Other Interim Standards

Beta/Photon Emitters 0 4mrem/yr Cancer Decay of radionuclides in natural and man-made deposits Alpha Emitters 0 15 pCi/L Cancer Decay of radionuclides in natural deposits

Combined Radium 226/228 0 5 pCi/L Bone cancer Natural depositsArsenic 0.05 0.05 Skin, nervous system toxicity Natural Deposits, Smelters, glass, electronics wastes,

orchardsTotal Trihalomethanes 0 0.10 Cancer Drinking water chlorination by-products

Notes: 1. Maximum contaminant level goal (MCLG) is a non-enforceable goal at which no known adverse healtheffects occur.

2. Maximum contaminant level (MCL) is a federally-enforceable standard.3. TT-Treatment Technique requirements established in lieu of MCL’s: effective beginning December 1990.4. MFL = Million Fibers per Liter longer than 10 um.5. *Contaminants with interim standards which have been changed.6. + = Less than 5% positive samples.7. ++ = Action Level 0.015 mg/L.8. # = Action Level 1.3 mg/L.9. Source: USAEPA publication EPA 815-K-97-002 (July 1997).


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Table 1-13: Typical Ground Water Quality Summary(General Mineral, General Physical & Inorgonic Chemicals)

Parameter/ Avg. Max Min Allowable Units of measurement Conc. Conc. Conc. Limit

General MineralpH (Standard Units) 7.3 7.6 7.1 No Standard Carbonate mg/L <5 <5 <5 No Standard Bicarbonate mg/L 142 269 87 No Standard Chloride mg/L 8 12 6 500Sulfate mg/L 9 12 6 500Calcium mg/L 23 45 12 No Standard Magnesium mg/L 9 21 5 No Standard Sodium mg/L 19 30 14 No Standard Copper mg/L <.005 <.005 <.005 1.3 (1.0)*Zinc mg/L <.02 <.02 <.02 5Iron mg/L <.1 <.1 <.1 0.3Maganese mg/L <.005 <.005 <.005 0.05

General PhysicalSpecific Conductance umhos/cm 279 463 182 1600Foaming Agents (MBAS) <.02 <.02 <.02 0.5Total Dissolved Solids (TDS) mg/L 214 372 136 1000Alkalinity mg/L as CaCO3 116 220 71 No Standard Hardness mg/L as CaCO3 94 199 55 No Standard Color CU <2 <2 <2 15Odor TON NDO NDO NDO 3Turbidity NTU .39 1.0 <.1 5

Inorgonics ChemicalsAluminum mg/L .06 0.2 ND 1.0Antimony mg/L 0 ND ND 0.006Arsenic mg/L .001 .006 ND .05Barium mg/L .167 0.371 0.101 2 (1.0)*Beryllium mg/L 0 ND ND 0.004Cadmium mg/L <.005 <.005 <.005 0.005Chromium mg/L <.005 .005 <.005 0.01Cyauide mg/L 0 ND ND 0.2Fluoride (Raw Water) mg/L 0.2 0.3 0.1 1.6**Lead mg/L <.002 <.002 <.002 0.05Mercury mg/L <.0005 <.005 <.0005 0.002Nickel mg/L 0 ND ND 0.1Nitrate (NO3) mg/L 2.8 3.5 <.5 10Nitrite (N) mg/L 0 ND ND 1.0Selenium mg/L <.002 <.002 <.002 0.02 (0.01)*Silver mg/L <.01 <.01 <.01 0.05Thallium mg/L 0 ND ND 0.002

* California Standard ** Fluoride added to maintain 1.0 mg/L

CU = Color Units mg/L = milligrams per liter (parts per million)ND = Non Detectable umhos/cm = micro-mhos per centimeterNDO = No Detectable OdorNTU = Nephelometric Turbidity UnitsTON = Threshold Odor Units


Section 1


Table 1-14: Typical Ground Water Quality Summary(Organics chemicals, Radioactivity & Microbiological)


Organic PesticidesDibromochloropropane (DBCP) ug/L < 0.02 < 0.02 < 0.02 < 0.02Ethylene Dibromide (EDB) ug/L < 0.02 < 0.02 < 0.02 < 0.02

Voltile OrganicsBenzene ug/L < 0.5 < 0.5 < 0.5 1.0Carbon Tetrachloride ug/L < 0.5 < 0.5 < 0.5 0.5Ethylbenzene ug/L < 0.5 < 0.5 < 0.5 680Pentachbrophenol (PCP) ug/L ND ND ND 1.0Polychlorinated Biphenyls (PCB) ug/L ND ND ND 0.5Tetrachloroethylene (PCE) ug/L < 0.5 < 0.5 < 0.5 5.0Trichoroethylene (TCE) ug/L < 0.5 < 0.5 < 0.5 5.0Vinyl Chloride (VC) ug/L < 0.5 < 0.5 < 0.5 0.5Xylenes ug/L < 0.5 < 0.5 < 0.5 1.75

RadioactivityGross Alpha Activity pCi/L 1.0 4.0 0.7 15.0Radon 222 pCi/L 646 1365 318 No Standard

Microbiological Coliform Bacteria % sample 1.02 3.92 0 5

Note: Additional organic chemicals are monitored and tested periodically as required by the National Primary Drinking Water Regulation (NPDWR)

ug/L = micrograms per liter (parts per billion) ND = Non Detectable pCi/L = Pico curies per liter

Table 1-15: Typical Ground Water Quality Summary(Secondary - Drinking Water Regulations)


Aluminum ug/L 6 190 ND 500Chloride mg/L 6 20 0 250Color CU 5 17 ND 15Copper mg/L ND ND ND 1.0Corrositivity - - - - non-corrosiveFluoride mg/L 0.2 0.3 0 2.0Foaming agents mg/L ND ND ND 0.5Iron mg/L 37 58 ND 300Manganese mg/L ND ND ND 0.05Odor TON 0 3 ND 3pH 7.7 8.2 7.3 6.5-8.5Silver mg/L ND ND ND 0.09Sulfate mg/L 13 47 0 250TDS mg/L 183 380 96 500Zinc mg/L ND ND ND 5

Note: Secondary Maximum Contaminant Levels (SMCL’s) are Federally non-enforceable and establish limits forcontaminants in drinking water which may affect the aesthetic qualities and the public’s acceptance ofdrinking water (e.g. taste and odor).

ND = Non Detectable TON = Threshold Odor NumberTDS = Total Dissolved Solids CU = Color Units

Water Quality for AgricultureThe exchange of ions alters the physical characteristics of the soil. Clay that carries a good excess of calcium ormagnesium ions tills easily and has good permeability. If the same clay takes up sodium, it becomes sticky andslick when wet and has very low permeability. It shrinks when dry into hard colds which are difficult to break upby cultivation.

High concentration of sodium salts develops alkali soils in which little or no vegetation will grow.

If the irrigation water contains magnesium ions in a quantity that equals or exceeds the sodium, a sufficientconcentration of calcium or magnesium will be retained on the clay particles of the soil to maintain good tilth andpermeability. Such water serves well serves well for irrigation, even though the total mineral content may be quitehigh.

These facts lead to the adoption, in 1948, of a factor called the “sodium percentage” as an approximate indicator ofthe suitability of water for irrigation (Table 1-16). This percentage is the ratio of the sodium ions to the total sodiumhazard.

In making the calculation, the amount of each constituent must be converted form parts per million to “equivalentsper million” equivalents per million are calculated by dividing parts per million by the chemical combining weightof each ion. Expressed in this way, equal concentrations of different ions are equivalent to their tendency to formany possible chemical combination. Multiplying parts per million by the following conversion factors will give theconcentration of each of the ions in equivalents per million.

Ion FactorCalcium (Ca) .04990Magnesium (Mg) .02884Sodium (Na) .04350

In 1954, the U.S. Salinity Laboratory proposed that the sodium-percentage idea be replaced by a more significantratio termed the “sodium-adsorption ratio,” or SAR. This ration is calculated from the following formula, theconcentrations of the ions being expressed in equivalents per million:

Development of excess sodium in soil will result from the use or irrigation water that has a high SAR value. Valuesof 18 or more are considered high; ratios of 10 to 18 are medium; values below 19 are low and offer little danger ofcreating a sodium problem.

Plants take up very little of the dissolved minerals form irrigation water. Most of the minerals in irrigation water,remain in the soil or remain dissolved in the unused portion of the water. If repeated irrigation results in too muchbuild-up of mineral salts, the productivity of the irrigated soil may be destroyed. Flooding of arid soil to facilitateleaching salts from soil is often employed.

Chemical analyses of water do not indicate that the water is free from harmful bacteria and hence suitable fordomestic use. Most groundwater, when sufficiently low in mineral content to be suitable for such use, are potableunless contaminated by the activities of man. The sanitary quality should be checked periodically if they are to beused without treatment to insure their continued freedom from harmful bacteria.


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Calcium++ + Magnesium++

2

Sodium+SAR =


Section 1


Table 1-16: Irrigation Water Classification - Sodium Percentage Method

Constituent Classification (see footnotes)

Class I Class II Class III

TDS 0 - 700 ppm 700 - 2,000 ppm Over 2,000 ppm

Chloride 0 - 150 ppm 150 - 500 ppm Over 500 ppm

Boron* 0 - 0.5 ppm 0.5 - 2.5 ppm Over 2.5 ppm

% Sodium** Under 60% 60 - 75% Over 75%

* - Boron is critical factor only in certain localities.

** - Percent of sodium (sodium & potassium) by weight. Convert parts per million of sodium (& Potassium),calcium, and magnesium to equivalents per million (EPM) by multiplying by the appropriate conversion factor.

% Sodium = EPM Sodium (& Potassium)/EPM Sodium + EPM Magnesium x 100

Classification: Class I, waters regarded as entirely safe for irrigation under ordinary conditions of climate and soil,even for sensitive crop plants; Class II, intermediate water which may be safe for certain conditions or certaincrops, yet may be unsafe under other conditions or for other crops; Class III, water with concentration of one ormore constituent too great to be safe for irrigation use, or at least unsafe in a great majority of cases.

Other factors must necessarily be considered, such as: a) climatic conditions, b) amount of irrigation inproportion to natural rainfall, c) soil conditions, and d) the species of crop irrigated. Any or all of these factorscan be as important as the chemical character of the irrigation water.

Water Quality CharacteristicsPhysical Characteristics. Potable water should be free from all impurities that are offensive to the senses of sight,taste and smell. The physical characteristics of water include turbidity, color, taste and odor, temperature andfoamability.

• Turbidity - The presence of suspended material such as finely divided organic material, clay, silt and otherinorganic material in water is known as turbidity. Turbidities in excess of 5 NTU (nephelometric turbidity units)are easily detected in a glass of water and are usually objectionable for aesthetic reasons. A turbidity level of lessthan 1 NTU is desirable.

• Color - Dissolved organic material from decaying biological life can cause color in water. Color is not normally anissue for groundwater sources at the well head, however, contamination can occur within the distribution system.Practical treatment techniques for ground water supplies are filtration, RO, adsorption with activated carbon andchemical oxidation (chlorine, ozone, etc.).

• Taste and Odor - Taste and odor in water can be caused by foreign matter such as organic compounds, inorganicsalts or dissolved gases. These materials may come from domestic, agricultural or natural sources. Water should befree of any objectionable taste or odor at point of use. Aeration, filtration, chemical oxidation or adsorption withactivated carbon can remove taste and odors.

• Temperature - The most desirable drinking water is consistently cool and does not have temperature fluctuationsof more than a few degrees. Ground water and surface water from mountainous areas generally meet thesecriteria. Most individuals find that water having a temperature between 50˚F and 60˚F (10˚C and 15˚C) is mostpalatable.

• Foamability - Foam in water is usually caused by detergent concentrations greater than 1 mg/L. Foamability is notnormally an issue for ground water supplies.

Chemical Characteristics. Formation material not only affect the quantity of water that may be recovered but alsoits quality. As surface water percolates towards the water table, it dissolves portions of the minerals contained in thesoils and rocks. Ground water, therefore, usually contains more dissolved minerals than surface water. Man-madechemicals, on the other hand, are more likely to be found in surface waters.

The chemical characteristics that are normally analyzed in a water sample are discussed as follows:

• Alkalinity - Alkalinity is imparted to water by bicarbonate, carbonate and hydroxide components. The presence ofthese components is determined by standard methods involving titration with various indicator solutions.Knowledge of the alkalinity components is useful in the treatment of water supplies.

• Chlorides - Most waters contain some chloride. It can be caused by the leaching of marine sedimentary depositsand pollutants. Chloride concentrations in excess of about 250 mg/L usually produce a noticeable taste indrinking water. An increase in chloride content may indicate possible pollution from sewage sources, particularlyif the normal chloride content is known to be low. Where only waters of very high natural chloride content areavailable, reverse-osmosis or electro-dialysis units may be used to produce potable water.

• Copper - Copper is found in some natural waters, particularly in areas where copper has been mined. Excessiveamounts of copper can occur in corrosive water that passes through unprotected copper pipes. Copper in smallamounts is not considered detrimental to health, but will impart an undesirable taste to the drinking water. Therecommended limit for copper is 1.0 mg/L. Copper is rarely found at such high levels as to require treatment,however, it can be removed by conventional coagulation, sedimentation and filtration by softening or RO.

• Corrosivity - The tendency of a water to corrode pipes and fittings is health-related as well as being of economicimportance, since the materials released into the water by corrosion may include lead, cadmium and other toxicmetals. The corrosivity of a water cannot be measured simply. However, equations have been developed thatpredict corrosivity reasonably well on the basis of temperature, total dissolved solids, calcium content, pH andalkalinity. These equations indicate the calcium carbonate stability of water - the tendency to either deposit ordissolve calcium carbonate (CaCO3), the most common scale-forming compound. In most cases, a water that isneutral or slightly scale-forming is preferred.

Water that is excessively corrosive can be stabilized - made noncorrosive - by the addition of lime and soda ash toincrease the pH and alkalinity, or by the addition of polyphosphates or silicates to form protective coatings on thepipe walls. These treatment processes are relatively complex, requiring trained operators and regular monitoring.

• Fluoride - In some areas, water sources contain natural fluorides. Where the concentrations fall within a certainrange, the incidence of dental caries have been found to be below the rate in areas without natural fluorides. Ithas been established that the presence of about 1mg/L of fluoride in a water supply will help prevent tooth decayin children. Excessive fluorides in drinking water supplies may produce fluorosis (mottling) of teeth, whichincreases as the optimum fluoride level (0.7 - 1.2 mg/L).


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Table 1-17: Optimal Fluoride Concentrations and Fluoride MCL’s

Annual Average of Maximum Recommended Control Limits of MaximumDaily Air Temperature* Fluoride Concentration (mg/L) Contaminant

°F °C Lower Optimal Upper Level (mg/L)

53.7 and below 12.0 and below 0.9 1.2 1.7 2.4

53.8 - 58.3 12.1 - 14.6 0.8 1.1 1.5 2.2

58.4 - 63.8 14.7 -17.6 0.8 1.0 1.3 2.0

63.9 - 70.6 17.7 - 21.4 0.7 0.9 1.2 1.8

70.7 - 79.2 21.5 - 26.2 0.7 0.8 1.0 1.6

79.3 - 90.5 26.3 - 32.5 0.6 0.7 0.8 1.4

* Based on temperature data for minimum of 5 years.


Section 1


Excess fluoride can be removed by ion-exchange using bone char or activated alumina, a relatively complexprocess requiring trained operators. RO units are a simpler alternative that may be appropriate for smaller systemshaving access only to waters of high-fluoride content.

• Hardness - Hard water retards the cleaning action of soaps and detergents, causing an expense in the form ofextra work and cleaning agents. When hard water is heated it deposits a hard scale on heating coils, cookingutensils and other equipment with a consequent waste of fuel. The scale formed by hard water coats the inside ofdistribution system piping, which can eventually cause significant reductions in water-carrying capacity. Soft water,on the other hand, may be corrosive, leading to the destruction of unprotected metal piping.

Calcium and magnesium salts are the most common cause of hardness and can be divided into two generalclassifications: carbonate (temporary hardness) or noncarbonate (permanent hardness). Carbonate hardness is alsocalled temporary hardness because heating the water will usually remove it. Carbonate hardness is responsible forscale formation as a result of carbonate precipitate which adhere to heated surfaces and the inside of pipes.Noncarbonate hardness is called permanent hardness because it is not removed when water is heated.Noncarbonate hardness is due largely to the presence of the sulfates and chlorides of calcium and magnesium inthe water.

A hardness of 75 - 100 mg/L as CaCO3 is usually considered optimal for potable water. Water harder than 300mg/L as CaCO3 is generally unacceptable. Water softer than 30 mg/L as CaCO3 will often cause serious problemswith corrosion. Chemical (lime-soda ash) or ion-exchange softening processes can be used to produce acceptablysoft water where only excessively hard water is available. RO may reduce hardness to an acceptable level;however, in some cases an RO unit will produce water having almost no hardness, which may cause corrosionproblems unless further treatment is used to stabilize the water.

Table 1-18: Hardness Classification of Potable Quality Water (Carbonate Hardness)

Water Characteristics Hardness Range (ppm)

• Soft < 50

• Mildly hard 51-150

• Hard 151-200

• Moderately hard 201-300

• Very hard > 300

Notes: 1) Commercial laundries prefer water at 50 ppm or less total hardness2) Public water supplier generally prefer water in the mildly hard range.3) Hardness of water is demonstrated most commonly by the amount of water required to produce suds.4) Carbonate Hardness is measure of the CaCO content of the water.

• Iron - Small amounts of iron are frequently present in water because iron is present in the soil and becausecorrosive water will pick up iron from unprotected pipes. The presence of iron in water is consideredobjectionable because it imparts a brownish color to laundered goods and affects the taste of beverages. Therecommended limit for iron is 0.3mg/L. A variety of methods are available for iron removal. Conventionalcoagulation, sedimentation and filtration are generally effective; however, chemical oxidation, aeration and certainsoftening processes are more practical for small-system ground water supplies.

• Manganese - There are two reasons for limiting the concentration of manganese in drinking water: (1) to preventaesthetic and economic damage to property and (2) to avoid any possible physiological effects from excessiveintake. The domestic water user finds that manganese produces a blackish color in laundered goods and affectsthe taste of beverages. The recommended limit for manganese is 0.05 mg/L. Essentially the same treatmentprocesses used to remove iron are used to reduce manganese levels. However, manganese is harder to removethan iron, because its precipitation is more pH dependent.

• Nitrates - Nitrate (NO3) can cause methemoglobinemia (infant cyanosis, or “blue baby disease”) in infants whohave been given water or fed formulas prepared with water having a high nitrate concentration. A domestic watersupply should not contain nitrate concentrations in excess of 10 mg/L (1 mg/L expressed as nitrogen). Water inexcess of normal concentrations, often found in shallow wells, may be an indication of seepage from livestockmanure deposits. In some polluted wells, nitrite will also be present in concentrations greater than 1 mg/L, and iseven more hazardous to infants. A sophisticated ion-exchange process, requiring complex facilities and trainedoperators, has been used to remove excess nitrate for large municipalities. RO units are more practical for smallground water systems.

• Organic chemicals - Organic chemicals include pesticides, herbicides, trihalomethane and volatile syntheticorganics. Careless use of pesticides and herbicides can contaminate water sources and make the water unsuitablefor drinking. The use of these chemicals near wells is not recommended. The SDWA sets maximum contaminantlevels for several common pesticides and herbicides.

Trihalomethanes are a group of organic compounds that form when chlorine reacts with humic and fulvic acids(natural organic compounds that occur in decaying vegetation). Trihalomethanes, potential carcinogens (cancer-causing agents), should not exceed 0.1 mg/L in drinking water.

Volatile synthetic organics occur in the waste products of various industrial processes and are commonly found ingroundwaters near heavily industrialized areas. At very high levels these chemicals have toxic effects, and at tracelevels they are suspected of being carcinogenic. Limits for many volatile organics have been established by theUSEPA and are regulated under the SDWA.

Organics can generally be removed by adsorption with activated carbon. Trihalomethanes can often be avoidedby altering the chlorination process. Most volatile organics can be eliminated with aeration.

• pH - pH is a measure of the hydrogen ion concentration in water. It is also a measure of acid or alkaline content.The pH values range from 0 to 14, where 7 indicates neutral water, values less than 7 indicate increasing acidityand values greater than 7 indicate increasing alkalinity. The pH of water in its natural state varies from 5.5 to 9.0.Determination of the pH value assists in the control of corrosion, the determination of proper chemical dosagesand adequate control of disinfection. The treatment processes used to control corrosivity and scaling involve pHadjustment.

• Sodium - The sodium content of water is usually unimportant because the sodium intake from salt is so muchgreater; but for persons placed on a low-sodium diet because of heart, kidney or circulatory ailments, orcomplications of pregnancy, sodium in water must be considered. When it is necessary to know the preciseamount of sodium present in a water supply due to dietary constraints, a laboratory analysis should be made. Theusual low-sodium diets allow for 20 mg/L sodium in the drinking water. When this limit is exceeded, persons onlow-sodium diets should seek a physician’s advice on diet and sodium intake.

When water is softened by the ion-exchange method, the amount of sodium is increased. For this reason, waterthat has been softened should be analyzed for sodium if a precise record of an individual’s sodium intake isrecommended. High sodium levels can be reduced with RO or electrodialysis units.

• Sulfates - Waters containing high concentrations of sulfate caused by the leaching of natural deposits ofmagnesium sulfate (Epsom salts) or sodium sulfate (Glauber’s salt) may be undesirable because of their laxativeeffects. Sulfate content should not exceed 250 mg/L. RO, ion-exchange or electrodialysis can be used to reducesulfate concentrations.

• Total Dissolved Solids - Total dissolved solids (TDS) is a measure of the water’s content of various dissolvedmaterials. Water with no dissolved solids usually has a flat taste, whereas water with more than 500 mg/L TDSusually has a disagreeably strong taste. Depending upon the chemical nature of the dissolved solids, RO,softening or ion-exchange may be used to reduce TDS content.


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Section 1


• Zinc - Zinc is found in some natural waters, particularly in areas where zinc has been mined. Zinc is notconsidered detrimental to health, but it will impart an undesirable taste to drinking water. The recommended limitfor zinc is 5.0 mg/L. Softening, RO, ion-exchange or electrodialysis will reduce zinc concentrations.

Biological Characteristics. Water for drinking and cooking purposes must be free from disease-causing organisms.These organisms include bacteria, protozoa, virus and worms.

• Bacteriological quality - The specific disease-causing organisms present in water are not easily identified, and thetechniques for comprehensive bacteriological examination are complex and time consuming. It has beennecessary, therefore, to develop tests that indicate the relative degree of contamination in terms of a single, easilyperformed test.

Many of the microorganisms that cause disease in man are transmitted through fecal wastes of infected individuals.The most widely used method of testing the bacteriological quality of water involves testing for coliform bacteriathat are always present when fecal contamination occurs. Coliform bacteria normally inhabits the intestinal tract ofman, and is also found in most domestic animals, birds and certain wild species. The methods used to testspecifically for coliform are the membrane filter test and the multiple-tube fermentation test. A third test, theheterotrophic (standard) plate count, determines the total number of bacteria in a sample that will grow undercertain conditions.

The SDWA establishes microbiological standards that drinking water must meet. Most ground water sources properlyprotected and developed, can meet these standards without treatment; however, disinfection is a recommendedsafeguard and may be required by some state or local health agencies. Chlorination of ground water also introducesa disinfected residual that helps maintain bacteriological quality of the water in the distribution system.

Other biological factors to be considered for ground water sources are; iron bacteria which can cause problems withstaining, tastes and odors. Sanitary well-drilling procedures will prevent the entrance of iron bacteria into a new well.Iron bacteria in an existing well can usually be eliminated by temporarily introducing a high chlorine concentration.

Table 1-19: Classification of Water by Total Dissolved Solids (TDS) Content

Water Characteristics Dissolved Solids Range (ppm)

• Fresh Water <1,000

• Slightly Saline (Brackish) 1,000-3,000

• Moderately Saline (Brackish) 3,000-10,000

• Very Saline (Seawater) 10,000-35,000

• Brine >35,000

• Heavy (Toxic) Metals - Arsenic, barium, cadmium, chromium, lead, mercury, selenium and silver can all causeserious health problems if present in drinking water in more than trace amounts. Table 1-20 lists the maximumpermissible levels for these toxic metals, also termed heavy metals. Softening processes and RO units can both beused to reduce the concentrations of toxic metals. Ion-exchange and precipitation with alum are also effective forcertain metals.

Table 1-20: Allowable Concentrations of Heavy Metals

Concentration ConcentrationSubstance mg/L* Substance mg/L*

Arsenic (As) 0.05 Lead (Pb) 0.05

Barium (Ba) 1 Mercury (Hg) 0.002

Cadmium (Cd) 0.010 Selenium (Se) 0.01

Chromium (Cr) 0.05 Silver (Ag) 0.05

*Milligrams per liter (mg/L) and parts per million (ppm) are essentially the same.

Radiological Characteristics. Natural radiation occurs in water, food and air. The amount of radiation to whichthe individual is normally exposed varies with the amount of background radioactivity. Water of high radioactivity isunusual; nevertheless, it is known to exist in certain areas, either from natural or man-made sources. Humanexposure to radiation or radioactive materials is known to increase cancer risks, and any unnecessary exposureshould be avoided. The concentrations of radioactive materials specified in the current regulations of the SDWA areintended to limit the human intake of radioactive substances so that the total radiation exposure of any individualwill not exceed those defined in the radiation protection guides recommended by the Federal Radiation Council.

Softening techniques and RO units are both effective in removing radioactive chemicals.

Water TreatmentRaw water obtained from natural sources may not be completely satisfactory for potable use. Surface water maycontain disease organisms, suspended matter, or organic substances. Groundwater is less likely to containpathogenic organisms than surface water, but it may contain undesirable tastes and odors or mineral impurities thatlimit its use or acceptability. Some of these objectionable characteristics may be tolerated temporarily, but suitabletreatment should be used to raise the quality of the water to the highest possible level for long-term use. Publicwater utilities must provide potable water, which meets the standards required by the SDWA and specified in theNPDWR. Even where a nearly ideal water source can be developed, it is still advisable to provide the treatmentequipment necessary to ensure aesthetically and bacteriologically safe water at all times.

Some of the treatment processes that may be used by a water utility, depending on the characteristics of the waterdrawn from its ground or surface source, are as follows:

• Pretreatment • Adsorption• Aeration • Reverse osmosis• Coagulation/flocculation • Fluoridation• Sedimentation • Stabilization (corrosion control)• Softening • Disinfection• Filtration

The order in which the processes are listed approximates the order in which they would typically be performed.Some of the processes have overlapping functions, and no utility would need to perform all of the processes. Theone process that should be used by every utility is disinfection.

The following material gives a brief description of each of the treatment processes. Water-quality goals and water-source characteristics must clearly be established to optimize the treatment process. Where the treatment processhas no or limited application to ground water sources, it will only be briefly discussed for completeness.

Pretreatment. Processes used to condition the water before it enters the main treatment processes are known aspretreatment. Pretreatment is normally applied to surface water sources exclusively; however, there are selectiveapplication to groundwater. Surface waters may require screening, microstraining, presedimentation, and chemicalpretreatment for algae and other nuisance organisms, depending on their quality. Typical forms of pretreatment forgroundwater are centrifugal sand separation, where improperly constructed or damaged wells must be used andchemical pretreatment to control iron bacteria.

Controlling Iron Bacteria. When dissolved iron and oxygen are present in the water, a group of organisms knownas iron bacteria derive the energy they need for their life processes from the oxidation of the iron to its insolubleform. They accumulate within a slimy, rust-colored gelatinous mass, which coats submerged surfaces and indicatestheir presence. Although this problem may occur in surface waters having high iron content, it is especiallyprevalent with groundwater sources.

Iron bacteria tends to incrust piping (reduce diameter), reducing the carrying capacity by increasing frictional losses.The bacteria may impart an unpleasant taste and odor to the water; they may discolor and spot fabrics andplumbing fixtures; and they may clog pumps, well screens, valves, and meters. A detectable slime also builds up onany surface with which the water containing these organisms comes in contact. Iron bacteria may be concentratedin a specific location and may periodically break loose and appear at the faucet in the form of rust. Iron bacteria in


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Section 1


wells also create an environment favorable to the growth of other organisms that can produce hydrogen sulfide, anexplosive gas that gives water a strong rotten-egg taste and odor.

The most effective solution to iron-bacteria problems is to eliminate the bacteria by injecting a hypochlorite solutioninto the well. Successful application within the well by the hypochlorite solution may be difficult to achieve, andpersistent problems may require repeated or even regular applications of hypochlorite. When pretreatment methodsare unsuccessful, other treatment processes will be required to produce a water of acceptable quality. These mayinclude aeration (to remove both iron and hydrogen sulfide gas), breakpoint chlorination, or a combination ofprocesses designed to oxidize the iron and remove it by coagulation and filtration.

Aeration. Areation brings air into intimate contact with water. It can be used to oxidize dissolved iron ormanganese, changing then into insoluble forms. A short period of storage may be needed to permit the insolublematerial to settle, and in some cases the precipitated iron or manganese cannot be removed successfully except byfiltration. Because of the time needed to oxidize manganese, waters with excessive manganese levels often requireoxidation with some added chemical, such as chlorine.

Aeration also increases the oxygen content of water deficient in dissolved oxygen. Carbon dioxide and other gasesthat increase the corrosiveness of water can be eliminated largely by effective aeration; however, the increase incorrosion caused by increased oxygen may partially offset the advantage of the decrease in carbon dioxide. Theaeration process can be used to remove odors from water and modified to remove man made Volatile OrganicCompounds (VOC’s) from polluted groundwater.

Many methods for effective aeration are available, including spraying water into the air, direct air injection into theflow stream, allowing water to fall over a spillway in a turbulent stream, or distributing water in multiplestreams/droplets through a series of perforated plates. If aeration is performed in an open system, adequateprecautions should be taken to eliminate possible external contamination. Whenever possible, a totally enclosedsystem should be provided to reduce the possibility of outside contamination.

Sedimentation and Coagulation/Flocculation. Sedimentation is a process of gravity settling and deposition ofcomparatively heavy suspended material in water. Sedimentation is normally followed by a coagulation/flocculationstep. Coagulation/Flocculation is used to combine small particles together into larger particles which can be settledout by further detention (after sedimentation detention) or filtration. Coagulation and flocculation requires chemicaladditive and mixing. Sedimentation and Coagulation/Flocculation has limited application to groundwater sources butis often employed in surface water supply and wastewater treatment processes.

Softening. Water softening is a process that removes minerals, primarily calcium and magnesium, that cause waterhardness. Softening is used where scale from hard water is a problem. It may also be used to remove undesirableheavy metals. Water may be softened by either the lime-soda ash or the ion-exchange process, both processesincrease the sodium content of the water, a factor that should be considered by people on low-sodium diets. Eachsoftening process has advantages and limitations. Other methods can also be used to soften water, such aselectrodialysis, distillation, freezing, and reverse osmosis. Although each of these processes can produce softenedwater, they are used only in unusual circumstances. Softening in generally performed when hardness exceeds 200ppm carbonate hardness. Refer to Table 1-19 for an overall hardness classification.

Lime-Soda Ash Softening. In the lime-soda ash process, lime and soda ash are added to the water and react withvarious salts of calcium and magnesium to form two insoluble precipitates, calcium carbonate and magnesiumhydroxide. The lime-soda ash process has greatest applicability for large water systems utilizing surface water.

Ion-Exchange Softening. The ion-exchange method removes hardness ions by exchanging or replacing them withsodium ions, which do not contribute to hardness. In this softening process, ion-exchange materials, such aspolystyrene resins, are placed in an ion-exchange unit through which unsoftened water is passed. The resins arenormally regenerated by passing brine (a salt-water solution) through the ion-exchange unit. The ion-exchangeprocess is used in household softeners and is favored in small water utilities using groundwater supplies.

Filtration. Filtration is the process of removing suspended matter from water as it passes through beds of porousmaterial. The degree of removal depends on the character and size of the individual grains of filter media, the


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depth of the media, and the size and quantity of the suspended matter. Groundwaters seldom requires filtration, butmost surface water sources must be filtered before disinfection. Types of filters that may be used include:

• Slow-sand gravity filters• Rapid-sand and high-rate gravity filters• Pressure filters.

Slow-Sand Gravity Filters. In a slow-sand filter, water passes slowly down through beds of fine sand at ratesaveraging 0.05 gpm/sq. ft. of filter area.

Rapid-Sand and High-Rate Gravity Filters. Rapid-sand and high-rate filters are the two systems most commonly usedby large water users. In these installations, water moves down through a filter bed of sand (rapid-sand filters) orsand and anthracite coal (high-rate filters) supported by a layer of gravel. Filtration rates range from 2 to 8 gpm/sq.ft., so relatively small filter plants can provide large volume of water on a daily basis.

Cartridge Filters. In Cartridge filters, water is pumped through a extended surface-porus filter medium under highpressure. The filter media is generally provided in the form of synthetic porus fabric attached to a cartridge core.Filtration rates can range from 2 to 10 gpm/sq. ft. depending on application and filter duty. There are a variety ofhigh capacity cartridge filter types commercially available. Pressure filters are commonly used to process water in awide variety of domestic, industrial and agricultural applications. Most cartridge filters can be set-up to backwashautomatically and operate with only periodic attention. Such units are particularly appropriate for smallutilities/installations. Filter trains can be inexpensively paralled for high capacity application.

Adsorption. Adsorption is used primarily to remove organic materials. It can also be used to remove organic ions(volatile organics, pesticides, etc.), fluoride and arsenic. In the adsorption process, water is brought into contactwith a material to which specific types of molecules will adhere. Since the molecules adhere only to the surface ofthe adsorbent material, a large surface area is required. This requirement is met by using porous adsorbentmaterials, which can provide a large surface area within a relatively small volume. The type of adsorbent materialused depends on the contaminate to be removed. For adsorption of organics from groundwater, the material used isgenerally granular activated carbon (GAC).

GAC is used when adsorption is needed continuously. The GAC is used like a filter media, similar to sand in arapid-sand filter. The filter like tank housing containing the GAC is called a contactor. GAC loses its ability toadsorb, depending on load, after 3 - 12 months and must be replaced or reactivated.

Reverse Osmosis and Electrodialysis. Several recently developed processes use semipermeable membranes toremove undesirable constituents from water. Membrane separation processes currently in use by utilities includereverse osmosis, membrane filtration, ultra filtration, and electrodialysis. Both reverse osmosis and electrodialysiscan be used to produce potable water from sea water or groundwater having a high concentration of dissolvedsolids, both processes can be used to remove a fairly broad range of chemicals. Power costs for the operation ofthe membrane processes are relatively high, and some water characteristics can cause membrane fouling.

Reverse Osmosis. In a reverse-osmosis unit, a pump forces water through a specially designed plastic membrane atextremely high pressure, in the 300 psig (2100 kPa) range. The water passes molecule by molecule throughopenings in the molecular structure of the membrane, leaving a high percentage of the contaminating chemicalsbehind. The contaminants removed remain in the water on the inlet (high-pressure) side of the membrane; they arenot deposited on the membrane itself. The efficiency of removal for a given chemical depends on the characteristicsof the membrane.

Most water require some pretreatment before reverse osmosis, usually filtration and sometimes softening and /orchemical additions, to prevent fouling of the membrane. RO can be so effective in removing minerals, that waterhardness can be dropped to such a level as to be corrosive, requiring stabilization. Commercial package treatmentunits using reverse osmosis are available that provide the necessary pretreatment. Such units may operate withminimal attention; however, the necessary periodic maintenance and chemical additions require that the operatorshave some training, which should be provided by the manufacturer of the RO unit.


Section 1


RO units are commonly used to desalinate saltwater where fresh water supplies are not available. The RO techniqueis also used in the manufacture of high purity water for use in the electronics and medical industry.

Electrodialysis. Like reverse osmosis, electrodialysis separates chemicals form water by the use of semipermeablemembranes. Instead of using pumps and high pressure to force water through the membrane, the electrodialysisunit is equipped with electrodes that pull negatively and positively charged atoms out of the water through selectivemembranes. Since only charged atoms (ions) are removed, electrodialysis does not remove as wide a range ofconstituents as reverse osmosis. The process has been used most widely for desalination of brackish water.

Fluoridation. Fluoridation is used to maintain fluoride concentrations in drinking water at levels known to reducetooth decay in children. Fluoridation (fluoride addition) is a optional enhancement to the water supply and is notmandated by federal regulation. The level must be closely controlled; too low a concentration will have no effect,and too high a concentration can cause mottling and pitting of the teeth. The optimum concentration varies withthe average annual air temperature, since children will drink more water in hot weather. Precise recommendationsare available from the appropriate regulatory agency. Refer to Table 1-17 for fluoride concentration levels based onair temperature.

Stabilization (Corrosion Control). Corrosion control is important in maintaining the structural strength and water-tight integrity of the distribution system and in ensuring that treated water does not pick up trace quantities ofhazardous metals from distribution and home pipelines. Whenever corrosion is minimized there is an appreciablereduction in the maintenance and possible replacement of water pipes, water heater, and other metallicappurtenances of the system.

Corrosion is an electrochemical reaction in which metal deteriorates or is destroyed when in contact withenvironmental elements such as air, water, or soil. Whenever reaction occurs, electric current flows from thecorroding portion of the metal toward the electrolyte or conductor of electricity, such as water or soil. The point atwhich current flows from the metal into the electrolyte is called the anode and the point at which current flowsaway from the electrolyte is called the cathode. Any characteristic of the water that tends to allow or increase therate of this electrical current will increase the rate of corrosion. The important characteristics of a water that affect itscorrosiveness include the following:

• Acidity. A measure of the water’s ability to neutralize alkaline materials. Water with acidity or low alkalinity ( ameasure of the concentration of alkaline materials) tends to be corrosive.

• Conductivity. A measure of the amount of dissolved mineral salts. An increase in conductivity promotes flow ofelectrical current and increases the rate of corrosion.

• Oxygen content. The amount of oxygen dissolved in water. The amount dissolved promotes corrosion bydestroying the thin protective hydrogen film that is present on the surface of metals immersed in water.

• Carbon dioxide. Forms carbonic acid, which tends to attack metallic surfaces.• Water temperatures. The corrosion rate increases with water temperature.

Chemical Corrosion Control. When the primary cause of corrosion is acidity, it is best controlled by neutralizationwith the addition of a soda ash solution (strong base).

Film forming corrosion inhibitors can be employed (with regulatory approval) to reduce corrosive attack on a waterdistribution system infrastructure. Typical film forming additives are polyphosphates and silicates which tend to coatand protect the interior of metallic piping. Inhibitors are affective when the pH is 7.0 or greater.

Non - Chemical Corrosion Control. The two steps involved in the corrosion process are oxidation and reduction. Ifeither can be interrupted, the corrosion process can be halted or minimized. Non -chemical preventative techniquescommonly employed to reduce corrosion in a distribution systems are; (1) cathodic protection, (2) anodic protectionand (3) coatings:

(1) Cathodic protection. Cathodic protection can be provided in two ways, impressed current or galvanic (sacrificialanode). The impressed current technique involves the application of a DC voltage to the metal which allowelectrons to flow in at a rate equivalent to the loss to corrosion. The impressed current technique is particularlyapplicable in preventing corrosion of steel structures such as large, elevated and ground level steel tanks. The

galvanic technique involves the use of a sacrificial anode. The anode must be of a higher corrosion potentialthan the material being protected. Magnesium is most commonly used in waterworks application, as it does notform a corrosion resistant oxide layer or exhibit corrosion resistant behavior with respect to iron (steel).

(2) Anodic protection. Involves a metal treatment technique, in which the metal is subjected to high voltage and/orchemical processing, which forms a polarized protective film. The metal surface characteristics are changed froma cathodic state to anodic condition as a result of the alignment of the oxide layer. The technique is commonlyknown as passivation as it changes the metal from an “active” readily corrodable state to a “passive” corrosionresistant state.

(3) Coatings. Coating can be provided in two forms, metallic or chemical. Metallic coating include hot dipping,electroplaying, cladding, mechanical plating, etc. Typical chemical coatings include paints, epoxy, tape andlinings. Metallic coatings are generally used for the protection of specific equipment components such as pumpsand valves. Chemical coatings are often employed to protect metallic piping and above ground infrastructure.Coatings are principally designed to isolate the metal surface from corrosive conditions.

The most common corrosion stabilization techniques utilized by small systems are the installation of dielectric orinsulation unions at problem locations in the distribution system, reduction of velocities and pressures, removal ofoxygen or acid constituents, and lining or use of non-corrosive materials (plastics) for distribution lines.

Corrosion and scale (incrustation) are related problems. The essential effect of corrosion is to destroy metal.Incrustation/scale, tends to clog open sections and line surfaces with deposits. A thin coating of mineral (calciumcarbonate) scale may help to protect pipes from corrosion and /or leaching of lead from old lead or lead packedjoint pipelines.

Disinfection. The most important water treatment process is disinfection, the destruction of all disease-causingbacteria and other harmful organisms that may be present in water. Disinfection is usually the last treatment processperformed. After disinfection, water must be kept in tanks or other storage facilities that will preventrecontamination if it is not used soon after disinfection.

The methods available for disinfection of drinking water fall into the three general categories; heat treatment,radiation treatment and chemical treatment. Heat treatment (boiling) or pasteurization (holding water at 161 F for 15seconds), is not practical for most system. Disinfection with radiation, typically ultraviolet light is generallyimpractical. Both the heat treatment and radiation processes require significant energy and does not have residualdisinfection capacity. The most common means of disinfection in the United States is chemical treatment, primarilywith chlorine and chlorine compounds. Chemicals used less frequently include bromine, iodine (not recommendedfor utilities serving permanent populations), and ozone.

Disinfection of water with chlorine involves the addition of pure chlorine or a chlorine-releasing compound. Aperiod of time is necessary after chlorine addition to allow disinfection to take place, and the chlorine concentrationmust be such as to ensure that disinfection will be completed before the water reaches the first user in the system.A slight residual chlorine concentration, in the distribution system, is desirable to prevent the regrowth of organismsafter the water is treated. In systems where a chlorine residual is maintained, the absence of residual in a given areaof the distribution system can indicate the possibility of a cross connection to a sewer or other nonpotable line. Theability to provide this residual is one of the primary factors in favor of using chlorination instead of some othermeans of disinfection.

Operation of a chlorination system requires a certain amount of training in operating, safety, and testing procedures.Publications and training programs designed for operations of chlorination systems are available through watersupply regulatory agency and the American Water Works Association. A brief overview of chlorination chemistry,equipment, and operating procedures is discussed below.

Chlorination Chemistry. The chemical reactions occurring when chlorine is added to water are relatively complexand not always intuitively obvious. Some of the important chemical concepts relating to chlorination can beintroduced by defining terminology and noting the major factors affecting dosages.


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The following Chlorination terminology is used to describe the chemistry of the chlorination process.

• Chlorine concentration. The concentration of chlorine in water is expressed in milligrams per liter (mg/L). Forwater, the terms parts per million (ppm) and mg/L indicate essentially equivalent concentrations.

• Chlorine feed or dosage. Chlorine dosage is the concentration of disinfectant, measured in mg/L, that is fed intothe water system by feeder or automatic dosing apparatus. Since some of the chlorine combines with othercompounds in the water, the chlorine dosage must usually be greater than the concentration of chlorine neededfor adequate disinfection.

• Chlorine demand. Chlorine demand is a measure of the amount of chlorine fed into the water that combines withthe impurities and, therefore, may not be available for disinfection action. Impurities that increase chlorinedemand include organic materials and certain reducing materials such as hydrogen sulfide, ferrous iron, andnitrites.

• Break point. The chlorine dosage at which the minimum residual occur. Breakpoint chlorination is adequate todisinfect but no residual is carried through the system.

• Combined available chlorine residual. In addition to organic materials that exert a chlorine demand, chlorine cancombine with ammonia or other nitrogen compounds present in water to form chlorine compounds that havesome disinfectant properties. These chlorine compounds are called combined available chlorine residual.(“Available” indicates they are available to act as a disinfectant.)

• Free available chlorine residual. The uncombined chlorine that remains in the water after any combined residualhas formed is called free available chlorine residual. This is the most effective disinfectant form of chlorine.

• Total available chlorine residual. The total concentration of chlorine compound available to act as disinfectants,including both free and combined chlorine residuals, is called total available chlorine residual.

• Chlorine contact time. Contact time elapses between the time when chlorine is added to the water and the timewhen that particular water is used. The contact required for chlorine to act as an effective disinfectant varies from30 min to 2 hours, depending on the concentration of the chlorine residual.

Factors Affecting Chlorine Dosage.When turbidity is less than 1.0 NTU’s,which is typical of groundwater, the primaryfactors that determine the disinfectantefficiency of chlorine are listed as follows:

• Chlorine concentration. The higher theconcentration, the more effective thedisinfection and the faster the disinfectionrate.

• Type of chlorine residual. Free chlorine isa much more effective disinfectant thancombined chlorine.

• Contact time between the organism andchlorine. The longer the contact time, themore effective the disinfection.

• Temperature of the water in whichcontact is made. The higher thetemperature, the more effective thedisinfection.

• The pH of the water in which contact is made. The lower the pH, the more effective the disinfection.

As a general rule, the chlorine dosage should be large enough to satisfy the chlorine demand and provide a freeavailable chlorine residual of 0.4 mg/L after a chlorine contact time of 30 min before the water reaches the first userbeyond the point of chlorine application. Water can usually be properly disinfected if a minimum contact time of 30min is ensured.


Section 1


Figure 1-21: Free Available Chlorine vs. Total Dosage

0 1 2 3 4 5 6 7

CHLORINE ADDED, IN PPM

5

4

3

2

1

0

RE

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UA

L C

HL

OR

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PP

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Breakpoint

Zero c

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Free r

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Superchlorination-dechlorination is used to overcome the problem of insufficient contact time in certain watersystems. In this method, chlorine is added to the water in relatively large concentrations (superchlorination) toprovide a minimum free available chlorine residual of 3.0 mg/L for a minimum contact period of 5 min. The excesschlorine is often removed (dechlorination) to eliminate objectionable chlorine tastes.

Chlorination chemicals. Three forms of chlorine are available for use in the disinfection of water: (1) purechlorine gas (actually shipped and stored as a liquid in pressurized containers); (2) calcium hypochlorite, sold as agranular powder or in tablet form; and (3) sodium hypochlorite, a high-strength form of liquid bleach. Large utilitiesuse gaseous chlorine almost exclusively, because of its economy. The operation of a gas chlorination system is fairlycomplicated, and special safety equipment is required in case of chlorine gas leaks. Smaller utilities commonlyselect systems using calcium hypochlorite or sodium hypochlorite, because of their relative simplicity and somewhatless stringent safety requirements.

Chlorination equipment. The equipment required for a chlorination system depends on the type of chemicalused. Both calcium and sodium hypochlorite systems use hypochlorite solution feeders (hypochlorinators) to meterthe liquid stock solution into water. Calcium hypochlorite also requires mixing and storage tanks for making up thestock solution from powder or tablets. Gas chlorination systems require a different type of chlorine feed system, aswell as specialized equipment for handling and safety. Typical chlorination requirements for hypochlorinators andgas systems are shown in figures 1-22 and 1-23 respectively.

Chlorine can be extremely corrosive at the point of injection. Care should be taken to insure that chlorine isintroduced into the system in a manner that does not corrode piping in the immediate vicinity of the injection point.

Figure 1-22: Hypochlorinator Equipment

Mix Tank

Day Tank

Solution Feeder

To Pointof Application


Section 1

Section 1C Water Quality & Treatment

Chlorination Monitoring. Residual chlorine in water can be measured as a chlorine compound (combinedavailable chlorine residual), as free chlorine (free available chlorine residual), and as both combined and freeavailable chlorine (total available chlorine residual). Chlorine is typically measured in terms of free chlorine forgroundwater applications.

Wherever chlorination is required for disinfection, chlorine residual should be tested at a frequency adequate toinsure and demonstrate adequacy of the disinfection process. The regulatory agency having jurisdiction over thewater supply, will generally specify a minimal sampling frequency. Records should serve as an indicator that properchlorination is being accomplished and as a guide in improving operations.

Ozone. Ozone is a powerful disinfecting agent. It’s disinfecting properties stem from the oxidizing properties ofozone. Ozone (O ) is unstable and loses one atom of oxygen readily when mixed and injected into the flow stream.The single “free” oxygen atom is responsible for oxidizing and killing water borne bacteria.

Ozone must be manufactured near the point of injection and is created by high voltage electric discharge in dry air.Ozone requires mixing to be affective as it is only slightly soluble in water. Ozone is also effective reducing odorand color, and improving taste. The disadvantages of ozone are it’s cost of manufacture and the lack of residualdisinfection capability.

Treatment System Maintenance. A maintenance routine should be developed so that all treatment equipment ischecked on a regular schedule. Almost all equipment will have daily, weekly, monthly, semiannual, and annualmaintenance requirements, which must be followed to ensure trouble-free operation. A general physical inspectionof the treatment facilities and equipment should be performed daily, if not remotely monitored electronically. Underno circumstances should the physical inspection interval exceed one week. Facility protection from freezing must beprovided based on climate requirements. Safety equipment must be well maintained and training should beconducted at a frequency adequate to maintain operator proficiency.

Treatment Process Overview. Ground water does not normally require substantial treatment; however, a varietyof treatment processes are available to remove contaminants. These individual processes may be arranged in a“treatment train” to remove undesirable contaminants from the water. The most commonly used processes includefiltration, flocculation and sedimentation and disinfection. Some treatment trains also include ion-exchange andadsorption. A typical water treatment plant would have only the combination of processes needed to treat thecontaminants in the source water used by the facility.

1-57

Figure 1-23: Typical Gas Chlorinator Deep Well installation Showing Booster Pump


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• Flocculation/Sedimentation. Flocculation refers to water treatment processes that combine small particles intolarger particles, which settle out of the water as sediment. Alum and iron salts or synthetic organic polyesters(alone, or in combination with metal salts) are generally used to promote coagulation. Settling or sedimentation issimply a gravity process that removes flocculated particles from the water.

• Flocculation/sedimentation is not normally used in treating ground water supplies.

• Filtration. Many water treatment facilities use filtration to remove remaining particles from the water supply.Those particles include clays and silts, natural organic matter, precipitants from other treatment processes in thefacility, iron and manganese, and microorganisms. Filtration clarifies water and enhances the effectiveness ofdisinfection.

• Ion-Exchange. - Ion-exchange processes are used to remove inorganic constituents if they cannot be removedadequately by filtration or sedimentation. Ion-exchange can be used to treat hard water. It can also be used toremove arsenic, chromium, excess fluoride, nitrites, radium and uranium.

• Adsorption. - Organic contaminants (pesticides), color, taste and odor-causing compounds can stick to the surfaceof granular or powdered activated carbon (GAC or PAC). GAC is generally more effective than PAC in removingthese contaminants. Adsorption is not commonly used in public water supplies.

• Disinfection (chlorination, ozonation). - Water is often disinfected before it enters the distribution system toinsure that dangerous microbes are killed. Chlorine, chloramines or chlorine dioxide most often are used becausethey are very effective disinfectants, and residual concentrations can be maintained to guard against biologicalcontamination in the water distribution system.

• Ozone. - A powerful disinfectant, but it is not effective in controlling biological contaminants in the distributionpipes. Ultra-violet light can also be used to disinfect water supplies.

Cost of Treatment and Delivery. Water treatment and delivery costs in the United States average slightly morethan $2/1,000 gallons and generally range from $1.00 to $5.00/1,000 gallons. Treatment accounts for about 15% ofthe total cost of water. The remaining 85% is a result of capital cost associated with facilities and equipment, laborfor operations and maintenance, and energy.



Section 1

Section 1D Water System Capacity Requirements 1-59

1D WATER SYSTEM CAPACITY REQUIREMENTSThere are no universally accepted rules for determining water system capacity requirements, as each must beevaluated on its individual merits. The guide lines for sizing a individual domestic water system very greatly fromthat of a self supplied industrial facility or public water supply.

The focus of the discussion is on groundwater supply systems, although the analysis presented may be applicableto other water supply sources as well. The four (4) most common areas of application requiring a water capacityanalysis are:

1. Rural/Residential Domestic and Farm Systems2. Public Water Systems3. Agricultural and Turf Irrigation Systems

The methodologies typically employed in determining water quantity, flow, pressure and storage requirements foreach application are discussed as follows.

Residential Domestic and Farm SystemsQuantity. A correctly designed ground water system must supply the quantity of water needed every daythroughout the year. The issue of quantity has two interrelated components, the first being the adequacy of thesource to produce the required volume and the second being the adequacy of the system to deliver the requiredvolume when needed. The adequacy of both are tied to the maximum daily usage requirement. At a minimum, thesource must be capable of providing the peak day water quantity over a 24 hour period. Ideally, the source shouldbe capable of meeting quantity requirements under peak use conditions. Usage and flow requirements arediscussed below.

Usage and Flow Requirements. Water usage/flow requirements can be classified as a intermittent or sustaineduse. Intermittent uses normally last no more than 7.5 minutes (10 min. max.) and include all household waterconsuming activities during the peak usage period. The intermittent usage is typically used to determine peak flow.Sustained use are those uses that last more than 10 minutes and include lawn watering, car washing, etc. Sustaineduses can be further classified as competing or non-competing. A competing sustained use would be lawn wateringat the same time that peak household uses are taking place. Competing sustained uses should be avoided; however,when this is not possible, the flow requirement should be included in the peak flow calculation.

Common rural household planning provides 50 gpd per person, of which one-third to one-half is for flushingtoilets. Peak daily use may reach 100 gpd per person during hot weather. If the peak use rate exceeds themaximum source capacity (well yield) , intermediate storage should be installed to help supply water during peakuse periods.

Water System Flow Rate. The instantaneous flow rate during peak use periods is referred to as the “peak flow”.Peak flow rates determine pump capacity, pipe size, temporary storage capacity and other water system features. Ina small groundwater system, the well pump should be capable of supplying the peak flow without the need forstorage. When storage is required, peak flow must be met using a booster pump and storage. Peak flows can beestimated as follows:

Home (Rural/Residential) Water System. The minimum flow rate for any rural/residential water system shouldbe 6 gpm; 10 gpm is more desirable. The system should ideally be capable of supplying the peak flow continuouslyfor 1 hour. A minimum of flow capacity of 10 gpm @ 30 psi is recommended for fire protection. In order to preventundersizing, the flow rate should never be less than the peak demand of the largest single fixture. For example, aflow rate of 20 gpm is needed to properly backwash some kinds of water filters. Future water requirements shouldbe estimated so that an adequate flow rate will be available when needed. See tables 1-21 below for estimatingpeak flow and table 1-23 for estimating water usage requirements.


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Section 1D Water System Capacity Requirements1-60

Table 1-21: Flow Rate Guide Lines for Private (Home) Water Systems - 7.5 Minute Peak

Flow Rate in gpm in Relation to Number of Bathrooms and Baths

No. of Bedrooms 1 Bath 1 1/2 Bath 2 Bath 3 Bath

2 Bedroom 6 gpm 8 gpm 10 gpm -

3 8 10 12 -

4 10 12 14 16 gpm

5 - 13 15 17

6 - - 16 18

Note: Always add sustained competing usage requirements that are likely to be used during household peak flowperiods if not otherwise accounted for.

Farmstead Water System. Where water for livestock production is supplied through the same system as water forthe home, the flow rate must be increased to meet those needs. The minimum flow rate for farmstead should be 8gpm; 10 gpm is more desirable. The water system for a farm or farmstead should supply the peak flow ratecontinuously for 2 hours. Larger farm enterprises with high capital investment, it may be desirable to provide atleast 20 gpm at 30 psi for fire control.

System flow rates for livestock based on consumption are listed in table 1-22. The farmstead flow rate is the sum ofthose flow rates added to the flow rate for the farm home, plus any additional special uses. Table 1-23 can be usedto estimate farm and other various sustained uses.

Example 1-2: 600 hog production unit plus residence (family of 4), 100 sq. ft. of lawn and garden,200 sq. ft. swimming pool, 1 hired worker

A. Farm1. 600 hogs @ 6 gal./hog = 3600 gpd Table 1-23 (6) d.2. 1 farm worker @ 60 gal/day = 60 gpd Table 1-23 (7) d.3. Flow rate @ 3600 gpd = 24 gpm Table 1-22

(livestock) B. Residence4. 4 people @ 100 gal./person = 400 gpd Table 1-23 (1)5. 4000 sq. ft. lawn @ .5 gal./sq. ft. = 2000 gpd Table 1-23 (4) a.6. 200 sq. ft. pool @ .3 gal/sq. ft. = 600 gpd Table 1-23 (4) b.7. Flow rate (4 br., 2 bath) = 14 gpm Table 1-22

Totals (peak day): 4860 gpd 38 gpm (min.)

* Note: It is recommended that the pump/source capacity be of at least 125% of the minimum calculated flow requirement (ie. 47.5 gpm).

Table 1-22: Flow Rates for Livestock production. *

Peak Use (gpd) Flow Rate (gpm) Peak Use (gpd) Flow Rate (gpm)

Up to 1000 8 (minimum) 6000 36

1500 12 7000 39

2000 16 8000 42

2500 20 9000 45

3000 24 10,000 48

4000 28 12,000 50

5000 32 15,000 55

* Flow rates are optimum for designing new systems and take into consideration expansion, fire control,sanitation and hydraulic waste removal.


Section 1


Table 1-23: Typical Rural/Residential and Farm Water Usage, Flow and Pressure Requirements

Usage Usage Usage Flow Flow Flow PressureUse/Fixture Max. Avg. Min. Usage Max. Avg. Min. Min.

(gpd) (gpd) (gpd) Comments (gpm) (gpm) (gpm) (psi)

(1) Rural/Residential Includes allOverall Usage 100 60 50 typical daily * * * 20(per person) “Domestic Uses”

(2) Domestic Usesa. Drinking Water - - - .25/.5gal/day/person - - - -b. Shower - - - 20-30 gal./shower 5 4 1 12c. Bath tub - - - 30-40 gal./bath 5 4 1 8d. Toilet - - - 3-7 gal./use 5 4 3 15e. Lavratory sink - - - 4 2.5 1 10f. Kitchen sink - - - 5 0 2 10g. Garbage disposal - - - 5 3 2 -h. Laundry (8 lbs.) - - - 2.5 2 1.5 -i. Car Washing - - - 20-45 gal./load5 5 2.5 2.5 0j. Dishwasher (Automatic) - - - 10-20 gal./load 2 1.5 1 -

(3) Water Treatmenta. Water Softener - - - 50-150 gal./cycle 8 - -

(regenerative)b. Backwash filter - - - 100-300 gal./cycle 15 - -

(4) Lawn & Gardena. Sprinkler Irrigation 50 25 10 .10-.50 gal./sq. ft. - - -

(per 100 sq. ft.) (per watering)b. Pond or Swimming 30 10 5 .05-.30 gal./sq. ft. - - -

Pool (per 100 sq. ft.) (per day)c. Sprinkler/ea. - - - 10 5 2 15d. 1/2” hose & nozzle - - - 5 3 2 20e. 3/4” hose & nozzle - - - 7 5 3 20

(5) Rural/Residential Min. Vol. Req. =Fire Protection * * * 600 gal. @ 10gpm for 1 hr. - - - 30

(6) Farm/Livestocka. Cow (dairy)/ea. 35 35 20 * • • 15b. Cow (dry or beef)/ea. 15 12 11 * • • 15c. Horses or mules/ea. 12 12 10 * • • 15d. Hogs/ea. 6 4 4 * • • 15e. Sheep or goats/ea. 2 2 1 * • • 15f. Chickesn/100 ea. 9 6 4 * • • 15g. Turkeys/100 ea. 20 15 10 * • • 15

(7) Farm / Misc. Usesa. Dairy Sanitation 200 150 100 10 8 4 20

(per head)b. Floor Sanitation 10 10 10 10 gal./100sq. ft. 10 5 5 20

(per 100 sq. ft.)c. Sanitary Hog Waller 100 75 50 - - - 20

(per head)d. Worker (8 hr. shift) 50 30 15 - - - 15

(8) Farm/Fire Min. Vol. Req.Protection - - - 2400 gal.@20 gpm for 2 hrs. 20 30

(9) Fixture Counta. 1-2 fixtures/fix. - - - Fixture count can be 2.50b. 3-5 fixtures/fix. - - - used to calculate 2.00c. 6-10 fixtures/fix. - - - additional flow rate 1.75d. 10-20 fixtures/fix. - - - requirements for non 1.25e. Over 20 fixtures/fix. - - - residential structures 1.00

Notes: 1. Use maximum usage values for developing peak flow requirements and storage needs.2. Average consumption values are applicable in the temperature range of 50-90°F.3. Above requirements are based average maximum consumption, use will vary with location, climate, specific animal type, dry

matter, etc.4. The amount of water for livestock and foul can be roughly estimated using the rule-of-thumb of; water reg. = 2 x amount of feed

consumed


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Table 1-24: Public and Commercial Individual Water Usage Requirements

Usage Avg. Usage RangeType of Establishment gpd gpd (L/day)

Airport (per passenger) 4 3-5 (11-19)Apartment, multiple family (per resident) 60 60 (227)Bathhouse (per bather) 10 10 (38)Camp:

Construction, semipermanent (per worker) 50 50 (189)Day, no meals served (per camper) 15 15 (57)Luxury (per camper) 120 100-150 (379-568)Resort, day and night, limited plumbing (per camper) 50 50 (189)Tourist, central bath and toilet facilities (per person) 35 35 (132)

Cottage, seasonal occupancy (per resident) 50 50 (189)Club:

Country (per resident member) 100 100 (379)Country (per nonresident member present) 25 25 (95)

Dwelling:Boardinghouse (per boarder) 50 50 (189)

Additional kitchen requirements for nonresident boarders - 10 (38)Luxury (per person) 120 100-150 (379-568)Multiple-family apartment (per resident) 40 40 (151)Rooming house (per resident) 60 60 (227)Single family (per resident) 60 50-75 (189-284)

Estate (per resident) 120 100-150 (379-568)Factory (gallons per person per shift) 20 15-35 (57-132)Highway rest area (per person) 5 5 (19)Hotel:

Private baths (2 persons per room) 60 60 (227)No private baths (per person) 50 50 (189)

Hospital (per bed) 300 250-400 (946-1514)Laundry, self-serviced (gallons per washing [per customer]) 50 50 (189)Motel:

Bath, toilet, and kitchen facilities (per bed space) 50 50 (189)Bed and toilet (per bed space) 40 40 (151)

Park:Overnight, flush toilets (per camper) 25 25 (95)Trailer, individual bath units, no sewer connection (per trailer) 25 25 (95)Trailer, individual baths, connected to sewer (per person) 50 50 (189)

Picnic:Bathhouses, showers, and flush toilets (per picnicker) 20 20 (76)Toilet facilities only (gallons per picnicker) 10 10 (38)

Restaurant:Toilet facilities (per patron) 8 7-10 (26-38)No toilet facilities (per patron) 2.5 2-1/2-3 (9-11)Bar and cocktail lounge (additional quantity per person) 2 (8)

School:Boarding (per pupil) 80 75-100 (284-379)Day, cafeteria, gymnasiums, and showers (per pupil) - 25 (95)Day, cafeteria, no gymnasiums or showers (per pupil) - 20 (76)Day, no cafeteria, gymnasiums, or showers (per pupil) - 15 (57)

Service station (per vehicle) 10 10 (38)Store (per toilet room) 400 400 (1514)Swimming pool (per swimmer) 10 10 (38)Theater:

Drive-in (per car space) 5 5 (19)Movie (per auditorium seat) 5 5 (19)

Worker:Construction (per person per shift) 50 50 (189)School or office (per person per shift) 15 15 (57)


Section 1


Table 1-25: Public Building - Water Flow Requirements by Fixture Count

Number of Fixtures

Type of Building 0-50 51-100 101-200 201-400 401-800 801-1200 Over 1200 See Notes

Hotels and Clubs Gpm per Fixture .65 .55 .45 .35 .27 .25 .20 ABMin. Capacity, gpm 25 35 60 100 150 225 300Man. Capacity gpm 33 55 90 140 210 300 -

Hospitals Gpm per Fixture 1.0 .8 .6 .5 .4 .4 .4 ABMin. Capacity, gpm 25 55 85 125 210 330 500Man. Capacity gpm 50 80 120 200 320 480 -

Apartments and Gpm per Fixture .5 .35 .30 .28 .25 .24 .24 AApartment Hotels Min. Capacity, gpm 16 30 40 65 120 210 300

Man. Capacity gpm 25 35 60 115 200 290 -

Mercantile Gpm per Fixture 1.3 .75 .70 .60 .55 .50 .50 ACMin. Capacity, gpm 40 70 80 150 250 460 620Man. Capacity gpm 65 75 140 240 440 600 -

Office Gpm per Fixture 1.1 .70 .60 .50 .37 .30 .27 ACMin. Capacity, gpm 35 60 80 140 210 320 380Man. Capacity gpm 55 70 120 200 300 360 -

Schools Gpm per Fixture 1.0 .60 .50 .40 .40 .40 .40 AMin. Capacity, gpm 20 50 70 110 180 340 500Man. Capacity gpm 50 60 100 160 320 480 -

A. Tables are based on equal number men and women. If major number of occupants are women increasecapacity 15%.

B. Where laundry is operated in connection with building increase capacity 10%.C. These estimates do not include water for special process work. The extra amount should be determined and

added to the total capacity requirement.

Table 1-26: Public and Commercial - Typical Load Values Assigned to Fixtures

Types of Supply Lead Value (gpm) Pressure

Fixture Occupancy Control Cold Hot Total (psi)

Water Closet Public Flush valve 10. 10. 15Water Closet Public Flush tank 5. 5. 8Urinal Public 1” flush valve 10. 10. 15Urinal Public 3/4” flush valve 5. 5. 15Urinal Public Flush tank 3. 3. 8Lavatory PublicFaucet 1.5 1.5 2. 8Bathtub PublicFaucet 3. 3. 4. 8Shower head Public Mixing valve 3. 3. 4. 12Service sink Offices Faucet 2.25 2.25 3. 8Kitchen sink Commercial Faucet 3. 3. 4. 8Drinking fountain Offices 3/8” valve 0.25 0.25 15Laundry machine (8 lbs.) Commercial Automatic 2.25 2.25 3. 10

Note: 1. For fixtures not listed, loads should be assumed by comparing the fixture to one listed using water insimilar quantities and at similar rates. The assigned loads for fixtures with both hot and cold watersupplies are given for separate hot and cold water loads and for total load, the separate hot and coldwater loads being three-fourths of the total load for the fixtures in each case.

2. The pressure specified above is the pressure in the supply near the water outlet while running. A 20 psiminimum system pressure is recommended.


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Table 1-27: Industrial - General Water Usage Requirements

Unit of Usage (gal.) perIndustry Production Production unit

CHEMICALSAlcohol, industrial gal 120(100 proof)Alumina (Bayer process) ton 6,300Ammonium Sulfate ton 200,000Butadiene ton 20,000-660,000*Calcium Carbide ton 30,000Carbon Dioxide ton 20,000(from flue gas)

Cottonseed Oil Gal 20Gunpowder or Explosives ton 2000,000Hydrogen ton 660,000Oxygen, liquid 1,000 cu ft 2,000Soap (laundry) ton 500Soda ash 58% ton 18,000(ammonia soda process)Sodium Chlorate ton 60,000Sulfuric acid 100% ton 650-4,875*(contact process)

FOODSBread ton 5000-1,000+Canning (general) 100 cases 750-25,000

(#2 cans)

Canning (specific):• Tomatoes ton 150-1870• Peaches ton 1800-5900• Olives ton 3000-10,400• Corn ton 1,000Dry Pack:• Garlic ton 2800• Raisins ton 2000Fresh Pack:• Artichokes ton 766• Cherries ton 11,932• Brussel Sprouts ton 813Corn (wet-milling) bu. corn 140-240Corn syrup bu. corn 30-40+Gelatin (edible) ton 13,200-20,000+Meat ton on the hoof 4,130-6000Seafood ton of raw prod. 3700Dairy:• Milk gal. 5• Butter ton 5,000• Cheese ton 1700-4000Sugar:• Beet sugar ton 2,160• Cane sugar ton 1,000

Unit of Usage (gal.) perIndustry Production Production unit

ALCOHOLIC SPIRITSBrewing 42 gal bbl. 470Distilling bu. grain 300-600Wine ton of grapes 625-2800

PAPER & PULPGround wood pulp Dry ton 4,600-5000*Paper ton 39,000-60,000Paper Board ton 15,000-90,000

PETROLEUMGasoline gal 20Oil refining 42 gal bbl. 770Refined products 42 gal bbl. 150-150,000*

SYNTHETIC FUELBy coal hydrogenation 100 bbl. 728,600From coal 100 bbl. 1,115,000From natural gas 100 bbl. 373,600From shale 100 bbl. 87,300

TEXTILESCotton:• Cloth Processing ton 10,000-360,000• Fiber to fabric ton 74,000Rayon:• Cuprammonium ton yarn 90,000-160,000+

(11% moist.)• Viscose ton yarn 200,000• Weave, dye & finish 1,000 yard 15,000Woolens ton produced 140,000

MISCELLANEOUSAluminum ton 1,920,000Cement, portland ton 750Coal & coke:• By product coke ton 1,500-3,600+• Washing ton 200Electric power (stm. gen.) kwhr 80-170*Iron ore (brown) ton 1,000Laundries:• Commercial ton work 8,600-11,400+• Institutional ton work 6,000Leather tanning: 100 lbs. raw hide 800Rock wool ton 5,000Rubber synthetic:• Bauna S ton 631,450• GR-S ton 28,000-670,000*Steel (highly finished) ton 65,000Steel (rolled) net ton 15,000-110,000*Sulfur mining ton 3,000

Note: 1. The water quantities reported above are for total plant intake, the amount which is piped into an establishment. The wide rangessometimes given reflect not only differences in processes or products, but differences in the use of water. In arid areas, where the mostrigorous conservation methods are economically feasible, “intake” is only a fraction of what it may be in areas where water is abundant,although “consumptive use” is virtually the same.

2. Data compiled from various sources * Range from no reuse to maximum recycling. + Range covers various products or processes involved.


Section 1


Public Water System Usage Requirements (Consumption for Various Purposes). The water furnished by a public water system canbe classified according to its ultimate or end use. System usage in a large system is normally figured based ongallons per capita per day (gpcd) values, which can be translated to a total daily usage in gallons per day (gpd) bymultiplying the gpcd values by the population served by the system. System usage in a small system can be directlyestimated in gpd using the requirements of the individual service connections. The typical uses are described asfollows:

Domestic. This includes water furnished to houses, hotels, etc., for sanitary, culinary, drinking, washing,bathing and other purposes. It varies according to living conditions of consumers, the ranges from 20 to 100gal (75 to 380 liters) per capita day. These figures include air conditioning of residences and irrigation ofgardens and lawns, a practice that may have a considerable effect upon total consumption in some parts ofthe country. The domestic consumption may be expected to be about 50 percent of the total quantity of waterproduced in the average city; but where the total gpcd consumption is small, the proportion will be muchgreater. A conservative estimate of 100 gpd per person or 350 gpd per household is often used by small watersystem providers to estimate the quantity requirements for a primarily residential system base.

Commercial and Industrial. Water so classified is that furnished to industrial and commercial plants. Itsimportance will depend upon local conditions, such as the existence of large industries, and whether or notthe industries utilize the public water supply.

The quantity of water required for commercial and industrial facilities supplied by water systems can beapproximated based on the floor area of the buildings served. The generally accepted water usageestimates based on building square footage is 0.3 gal./ft. per day.

Specific water supply requirements for industrial and commercial facilities can be estimated using Tables 1-25 and 1-27. The calculated requirement can be used to determine service size if larger than normallyprovided by a public water system based on facility floor area.

Public Use. Public buildings, such as city halls, jails, and schools, as well as public service-flushing streets andfire protection-require much water for which, usually, the city is not paid. Such water amount to 10 to 35gpcd. The actual amount of water used for extinguishing fires does not figure greatly in the averageconsumption, but fires will cause the rate of use to be high for short periods.

Loss and Waste. This water is sometimes classified as “unaccounted for”, although some of the loss and wastemay be accounted for in the sense that its cause and amount are approximately known. Unaccounted-forwater is due to meter and pump slippage, unauthorized water connections and leaks in mains. Unaccounted-for water, and also waste by customers, can be reduced by careful maintenance of the water system and byuniversal metering of all water services. In a system 100 percent metered the unaccounted-for-water, exclusiveof pump slippage, will be about 10 percent.

The total consumption will be the sum of the foregoing uses and the loss and waste. The probable division andbreakdown of water consumption in the U.S. is shown in Table 1-29. The average daily per capita consumption isestimated at 175 gpcd (670 lpcd), although the usage in various American cities ranges from 35 to 530 gpcd. Factorwhich affect water consumption include but are not limited to; system size, presence of industries, quality of thewater, cost, delivery pressure, climate, characteristics of the population, metering and system efficiency.


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Table 1-28: Projected Consumption of Water for Various Purposes

Consumption

Average Range

Use gpcd % gpcd

Domestic 80 44 20 - 100

Industrial 42 24 0 - 232

Commercial 26 15 0 - 143

Public 15 9 10 - 35

Loss & Waste 12 8 5 -20

Total: 175 100 35 - 530

Note: 1. gal. = liters x .2642. The values listed in the above table are most applicable to systems having a population of 25,000 or

more.3. Public use requirements for small systems are recommended to be at 35 gpcd, which would increase the

average consumption to 195 gpcd.

Accurate population forecasting and knowledge of the system user base are critical for the accurate determination ofwater quantity requirements in a large system.

Flow Requirements (Rates of Consumption). In the absence of reliable water usage information and historicaldata, maximum daily consumption is likely to be between 180 and 200% of the annual average daily consumption.Table 1-29 lists various historical rates of consumptions for various U.S. Cities.

Rules of thumb, based on the R.O. Goodrich formula are listed as follows:

1. Max. day consumption = 180% of avg. daily consumption2. Max. week consumption = 148% of avg. weekly consumption3. Max. month consumption = 128 % of avg. monthly consumption4. Min. day consumption = 25% to 50% of avg. daily consumption

Note: The rules of thumb are most applicable to a small municipality with a primarily residential base population.Larger cities will generally have smaller peaks.

The maximum hourly consumption is generally taken as 150% of the average for that day. Knowing the userpopulation or the number of service connections (typ. 2 people per connection) and the average gpcd consumption,the peak delivery flow rate (gpm) required of the system can be calculated. Various calculations are illustrated below,assuming 175 gpcd annual average consumption and 100 service connections (200 person system).

1. Q max. day pk. = 175 (1.8) (1.5) (200) 2.5 = 236, 250 gpm2. Q avg. day pk. = 175 (1.5) (200) (2.5) = 131,250 gpm3. Q avg. day = 175 (200) (2.5) = 87,500 gpm4. Q min. day = 175 (200) (2.5) (.25) = 21,875 gpm

Note: 1. Small water systems using average system wide gpd values, in lieu of gpcd, can use the same flow ratecorrection factors.

2. Q max. day pk. = (gpcd) x (max. day consumption factor) x (max. hour factor) x (population) x (gpcd togpm conversion).

Table 1-29 lists consumption statistics for various cities. Peaks of water consumption in the system will affect designof the distribution system. Peaks ranging from 1000 to 300% of the annual average are not uncommon inpredominantly residential areas. Commercial and industrial users tend to reduce peaks.


Section 1


Table 1-29: Recorded rates of water consumption in various U.S. Cities

Average daily per Maximum one-day Maximum incapita consumption consumtpion in a proportion to

City (gal) 3-year period (gal) average, %

Albany, N.Y. 177 227 128El Paso, Tex. 118 195 165

Albuquerque, N. M. 106 202 190Waterloo, Iowa 101 165 163Fort Smith, Ark. 125 172 138

Tyler, Tex. 98 196 200Monroe, La. 154 231 150

Pomona, Calif. 166 288 173St. Cloud, Minn. 73 185 254

Salina, Kan. 159 358 225Ashtabula, Ohio 202 260 129

Population Densities. General population density estimates for use in approximating water requirements in largepublic water systems are presented below. This information should only be used in the absence of specificpopulation data for which the water system is serving.

Municipal population density rarely exceed 30 to 40 people per acre. Densities generally range from 15 per acre insparsely built-up residential areas to 35 to 40 per acre in closely built-up single family residential areas with smalllots. In apartments, populations densities can range from 100 to 500 per acre. In commercial districts the populationwill be highly variable according to development.

Pressure Requirements. There are wide differences in the pressures maintained in distribution systems in variousU.S. cities. The differences stem primarily form topography, user make-up of the system and capabilities of thedistribution system. A service pressure range of 20 to 40 psi (150 to 300 kPa) is generally adequate for systems witha residential user base. Commercial and Industrial users prefer delivery pressures in the 30 to 50 psi range.

Service pressure for fire fighting purposes, via direct connection to distribution system through hydrants, is bestaccomplished at a pressure range of 60 and 75 psi for residential and commercial/industrial services respectively.The lower pressures are generally adequate provided pumper trucks are used to boost hydrant pressure.

The American Water Works Association (AWWA) recommends a nominal system static pressure of 60 to 75 psi (400to 500 kPa) as presenting the following advantages:

1. It will supply ordinary consumption of buildings up to 10 stories in height.2. Effective automatic sprinkler service is possible in buildings up to four stories.3. It permits direct hydrant service for a hose stream, thus insuring quick action by fire departments.4. A larger margin is allowed in fluctuations of local pressure to meet sudden drafts and to offset losses due to

partial clogging of service piping.

The disadvantages of increased system pressure are; (1) the availability of water under pressure stimulates its use,(2) increases leakage and (3) requires greater energy to maintain system pressure. An increase in pressure from 25to 45 psi is often accompanied by 30% increase in consumption. In a poorly maintained system, higher pressurewill increase loss and waste (leakage) within the system. An increase in the average pressure from 40 to 50 psi islikely to increase system wide loss and waste by 10.6%. The relationship between pressure and flow is:

psi (2)

psi (1)gpm (1) =

gpm (2) =


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A pressure increase from 40 to 50 psi will also increase energy consumption for a given volume of water byapproximately 25%.

Main pressures should not exceed 100 psi or drop below 20 psi. Pressures greater than 100 psi often exceed therating of piping material resulting in breakage. High system pressures also promote leakage losses within thesystem. At pressures less than 20 psi; internal distribution problems are created for users and fire fighting capacity isadversely impacted.

Pressure zoning via pressure regulating valves and/or booster stations are utilized where system topography wouldotherwise create high and low pressures outside established norms. Low pressure within the systems wheretopography is not an issue; can often be remedied with the construction of parallel feeder mains, a new supplysource (water well) or storage tank centrally located within the zone of low pressure.

Storage Requirements. Water is stored to equalize pumping rates over the day, to equalize supply and demandover a long period of high consumption, and to furnish water for emergencies such as fire fighting and breakdown(pump failures, line breaks, etc).

Ideally, the best storage system is one that allows for the water to be stored with maximum potential energy,allowing stored water to flow back into the system under the force of gravity. Elevated storage is ideal from thisstand point however, they are often to expensive to erect for small systems and undesirable in siesmicly activeareas. Elevated steel tanks are available in capacities up to 4,000,000 gallons. Hydropneumatic tanks can alsoaccomplish these objectives; however, there storage capacity is extremely limited and are not generally acceptablefor fire protection. Use of Hydropneumatic pressure tank are normally confined to small system.

Other storage methods include surface tanks and aquifer storage which is growing in popularity. Surface tanksnormally receive water direct from the well and are boosted from the tank into the system via pressure controlled-staged pumping. Aquifer storage has applicability in groundwater supplied systems where construction of highcapacity water wells are possible. Well pumps are sized based on the maximum practical yield of the well andcontrolled by Variable Frequency Drives (VFD’s) to maintain system pressure. Aquifer storage requires theavailability of emergency power to supply the system should power be lost. Systems which employ VFD’s requireminimal buffer storage during periods of low activity.

Regardless of the storage method employed, storage should be disbursed throughout the system to better servicepeak demand. Storage located in the immediate vicinity of wells result in poor pressure distribution throughout theoutlying areas of the system.

Storage capacity is a function of the load characteristics of the system. A value of 15% to 30% of the maximum dailyuse is generally considered adequate for larger systems. A value of 2 times the average daily summer seasonconsumption is sometimes used to approximate storage requirements for small systems. Storage capacity needs, insystems where wells of limited capacity requires considerable scrutiny.

It is desirable for pumping plants to provide the average daily system demand, with the excess being pumped tostorage during off peak periods. Storage in conjunction with direct supply, must be capable of meeting peak daydemands and flows. Storage needs are best determined through the analysis of demand records and considerationof future potential increases in demand.

The Insurance Services Office (ISO), grades cities based upon their fire defenses facilities. The adequacy of thewater system to meet the average consumption for the maximum day demand and calculated fire flow (maximum12,000 gpm for large systems) at a minimum delivery pressure of 20 psi will result in favorable insurance rating. Fireflow requirements for small systems is beyond the scope of this discussion.


Section 1


Agricultural and Turf Irrigation SystemsAgricultural Irrigation. The information presented in this section is intended to provide overview of the variousirrigation system types, issues and considerations for the purposes of preparing course estimates of systemrequirements such as system pressure, flow and water requirements based on crop type, soil and climaticconditions.

Irrigation is primarily used to supplement natural rainfall to supply the total crop water usage (evapo-transpiration -ET) needs, except in the arid areas (western U.S.) where irrigation is often required to provide the total crop needsas a result of the lack of precipitation during the summer growing season. The correct amount of water to applywill depend on the crop - which determines the overall amount of water to be applied and root zone penetrationdepth requirements, the soil - which determines the application rate and duration, and climatic conditions - whichdetermines the frequency of application.

Crop Water Usage & Irrigation Scheduling. The ever increasing cost of water and associated cost to pump, havelead to the development of more efficient irrigation schemes and methods in which predict the precise amount ofwater required to facilitate optimal crop yields. Crop water usage estimates and irrigation scheduling has evolvedinto a highly refined science. Techniques commonly employed to predict specific irrigation needs in areas wherewater cost and/or avail-ability are at a premium are ETp (evapotranspiration potential) and soil moisture analysis viamoisture meters (moisture probe tensiometers). In the absence of such information, irrigation requirements can beestimated using the information tabulated in this section.

The forecasting of irrigation water requirements using ETp involves calculating a base vegetative water usage ininches per day/week/month and multiplying it by the specific crop coefficient to yield the specific crop water usageover the time period analyzed. Soil moisture metering is used to directly measure the soil moisture content, whichwhen considered with the soil type, can be used to predict when irrigation is required.

Soil Considerations. Clay soils can hold as much as 40% of their dry weight in moisture, in contrast to sandy soilswhich may retain less than 8%. Not all of the moisture contained in soil is available for crop use. When theavailable soil moisture content is reduced to a value of approximately 2% for sandy soils and 25% for clay soils,plant roots can not access the trapped water. Unless water is applied, the plant will wilt and eventually die off.Water should be applied before the wilting percentages are reached, to prevent crop damage (over stressing).

Sandy soils retain little moisture and require frequent irrigations, a 1 inch application of water will result in a 12inch penetration. Loam soils retain more moisture relative and require less frequent irrigations when compared tosandy soils, a 1 inch application of water will result in a 6 to 10 inch penetration. Clay soils hold a higherpercentage of water when compared to other soil types and require infrequent irrigations, a 1 inch application willresult in a 4 to 5 inch penetration.

Methods of Irrigation & System Considerations. Irrigation methods can be classified into two broad categories;surface and subsurface, with surface irrigation being the most prominent. Surface irrigation can be further brokendown into three categories by application methods; which are sprinkler, flood and drip (micro-irrigation). Sprinklerirrigation methods include solid set, center pivot, linear and hand move systems. Flood irrigation methods generallyinclude furrow, boarder strip and check / ponding methods. Drip irrigation methods include traditional emittertypes, misters, micro sprinklers, trickle and porous tubing. Subsurface irrigation methods require the distributiontubing and dripper to be buried.

The selection of the irrigation method is a function of many factors; which includes but is not limited to the costand availability of water, type of crop (orchard, row crop, permanent pasture, etc.), frost protection capability, saltleaching and pre-irrigation needs. Sprinkler and drip irrigation method require a pressurized distribution to properlyapply water, but generally have a much higher application (irrigation) efficiency than flood systems. Drip andrelated subsurface system generally require course filtering of the water supply before introduction into the system. General system issues and considerations are summarized in Table 1-30.


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Table 1-30: Agricultural Irrigation Method Comparisons

Pressure Application Energy Initial LaborSystem Type Reg. Efficiency Efficiency Cropping Cost Req. Maint. Filtration

Sprinkler (impact)• Fixed-stationary 40-80 psi moderate moderate perm./field high low low NR• hand move-aluminum 40-80 psi moderate moderate row/field high high moderate NR• center pivot/linear move 60-100 psi moderate moderate-low perm./field high low moderate NR• Traveling (water cannon) 80-120 psi moderate low field moderate low moderate NR

Flood• furrow 1-5 psi moderate-low (2) high row low moderate low NR• boarder strip 1-5 psi moderate-low (2) high perm./field moderate low low NR

(concrete piping delivery)• check 1-5 psi low (2) high perm./field low low low NR

Drip/Subsurface• emitter types 20-50 psi high high permanent high low moderate (1) Reg.• micro sprinklers 20-50 psi high high permanent high low moderate (1) Reg.• porus tubing 20-50 psi high high permanent high low moderate (1) Reg.

Notes: (1) Drip & subsurface irrigation methods generally require course filtration prior to introduction into the irrigation system.(2) Energy efficiency relative to pumping is high for flood type system, as above ground head requirements are relatively low;

however, more water (longer pumping) is often required to meet crop water requirements.

Irrigation Efficiency. Irrigation efficiency is optimized when just enough water is applied to increase the soilmoisture content of the root zone to the maximum water holding capability of the soil. Over irrigation (deepirrigation) will force water below the root zone, where it can not be recovered by the plant. Under irrigation(shallow irrigation) can lead to high evaporative losses and insufficient water available to the crop. Irrigationefficiencies typically range from 90% to 25% for well operated and monitored systems. Low efficiency is principallya function of the irrigation method; typical efficiencies for sprinkler, flood and drip irrigation methods range from80-50%, 60-25% and 90-70% respectively. As an example, crops irrigated using impact sprinkler (overhead) methodswill require 20-50% more water be applied than the plant actually requires for optimum growth.

Energy Efficiency. Irrigation efficiency and irrigation energy efficiency are not directly related; however, the lattercan often be improved by using one or more of the following conservation devices / systems; such as reservoirstorage, off peak pumping, variable frequency / speed drives and low head irrigation systems where applicable.

Run-Off Recovery & Drainage. Recovery of surface drainage / run off water (tail water) from irrigation via floodmethods, is often employed to increase irrigation efficiency, and conserve water and energy. Estimating tail waterrecovery system requirements (pump size, reservoir requirements, piping, etc.) should be performed on a specificsystem basis. In the absence of specific data, the following rules of thumb may be employed to estimate run-offflow rates

• Surface drainage - field (row) crops: 10 gpm per acre• Surface drainage - truck (vegetable) crops: 15 gpm per acre

Subsurface Drainage. Subsurface drainage of irrigated fields is sometimes required in the presences of alkali soilsand / or in fields which have a underlaying hard pan / confining layer, which retains water to such a degree thatmakes crop growth and tillage impossible. Subsurface drainage is typically accomplished using tile drainage system.The generally accepted rule of thumb for estimating subsurface drainage flow rate is:

• Subsurface drainage - 7 gpm per acre

The water quality associated with subsurface drainage is generally not suitable for irrigation water without treatmentand/or dilution. In general, subsurface drainage water has a significantly higher mineral (salt) content than irrigationwater supplies.

Sprinkler System Design Procedure. A complete discussion of the design issues / considerations associated with thevarious irrigation methods is outside the scope of this manual. The stationary (fixed / permanent set) sprinkler


Section 1


irrigation method procedure is illustrated below in Figure 1-24 below, as it is the most applicable to both the turfand agricultural irrigation market, and is the most illustrative of the various concepts developed in this section.

Turf & Landscape Irrigation. TheU.S. Department of Agricultureestimates on the average, thathealthy turf requires one inch ofwater per week (1”/wk.). One inchof water per week over an acreequals 27, 150 gallons. Warmer /arid clients can require significantlymore than 1”/wk. during thesummer months to maintain healthyturf. Applications rates should belimited to 0.25”/hr., as run-off canbecome a problem at higher rates.Landscape foliage and floweringplant water requirements can verysignificantly from the guidelines forturf. In the absence of specific data(plant type, planting density,exposure, etc.), landscape waterusage is often approximated at 50%of the value specified for turf overthe total landscaped area. Purelylandscaped zones generally requireless frequent irrigations than turf.

Turf water requirements not met bynatural precipitation are mostfrequently met by sprinklerirrigation. Turf sprinkler systems aretypically designed to handle thetotal (maximum) irrigation needs ofthe landscape foliage and turfrequirements without the benefit ofsupplemental precipitation. Wherelarge expanses of turf as

encountered; such as golf courses, parks and cemeteries - reservoir storage is commonly used in the form ofartificial lakes, ponds and/or storage tanks. This intermediate holding step is done for a variety of reasons rangingfrom ascetics to energy conservation to application flexibility. In cases where there is a significant temperaturedifferential between the water supply and ambient surface temperature, surface storage is often used to bring theirrigation water supply temperature closer to ambient for improved turf health.

Turf and landscaping irrigation water requirements can have a significant impact on both public and private watersupplies and should be carefully considered in the system design. In the arid portions of the U.S., the irrigation loadmay account for 50% or more of the water volume used on a daily basis during the summer months. Golf courseirrigation water requirements are discussed below to illustrate the impact associated with large expanses of turf andlandscape on a water supply system.

Golf Course Irrigation. On the average 18 hole golf course; greens and tees are typically watered in sets at flowrates in the range of 150 to 175 gpm @ 30 to 40 psi. Fairways averaging 300 yards long by 60 yards wide (52 acres)are typically watered in sets at flow rates in the range of 475 to 500 gpm @ 30 to 50 psi. At 27,150 gallons perweek, a 52 acre fairway will utilize approximately 1,415,000 gallons each week. A well maintained 18 hole coursecan consume up to 25,470,000 gallons of water per week during the peak irrigation season. Sprinkler pumping isnormally done over fifty hours each week (3000 minutes). The average 18 hole golf course sprinkler irrigationsystem is operated seven hours per night, seven nights per week.

Figure 1-24: Stationary Type - Sprinkler System Design Process Flow Chart


Sect

ion

1


Table 1-31: Irrigation - Application Rates for Various Crops @ 100% Irrigation Eff.*

Cool Climate Moderate Climate Warm Climate

Acre - in. gpm Acre - in. gpm Acre - in. gpmper Acre per per Acre per per Acre per

Crop per day Acre per day Acre per day Acre

Pasture .15 2.8 .20 3.8 .30 5.7Alfalfa .12 2.3 .16 3.0 .25 4.7Grain .15 2.8 .20 3.8 .22 4.2

Potatoes .10 1.9 .12 2.3 .14 2.6Beets .12 2.3 .15 2.8 .20 3.8

Orchards .15 2.8 .20 3.8 .25 4.7Orchard w/cover .20 3.8 .25 4.7 .30 5.7

* The above application rates are ideal and assumes the total amount of water applied is used by the crop (100% irrigation efficiency), the tabulated values require corrected for actual irrigation efficiency. Typical efficiencycorrection factors are: for Hot Dry Climate: 1.67 (flood)/1.25 (sprinkler)/1.10 (drip)

for Moderate Climate: 1.43 (flood)/1.20 (sprinkler)/1.05 (drip)for Humid or Cool Climate: 1.25 (flood)/1.15 (sprinkler)/1.05 (drip)

Table 1-32: Irrigation - Area by Depth of Coverage

Flow Number of acres covered in 12 hours

Depth of water

gpm cfs 1” 2” 3” 4” 6” 8” 10” 12”

20 .045 .53 .26 .17 .13 .09 .07 .05 .0450 .111 1.33 .66 .44 .33 .22 .17 .13 .11100 .223 2.96 1.33 .88 .66 .44 .33 .26 .22150 .335 3.98 1.99 1.33 .99 .66 .50 .40 .33225 .502 5.97 2.99 1.99 1.49 .99 .75 .60 .50300 .668 7.96 3.98 2.66 1.99 1.33 .99 .80 .66400 .891 10.61 5.31 3.54 2.65 1.77 1.33 1.06 .88700 1.560 18.58 9.28 6.18 4.64 3.09 2.32 1.86 1.55900 2.008 23.85 11.95 7.96 5.97 3.98 2.98 2.38 1.991200 2.675 31.82 15.92 10.61 7.95 5.31 3.98 3.18 2.651600 3.565 42.35 21.20 14.15 10.61 7.07 5.31 4.23 2.533000 6.680 79.50 39.75 26.50 19.88 13.25 9.94 7.95 6.624500 10.030 119.30 59.70 39.75 29.85 19.90 14.93 11.93 9.956000 13.360 159.10 79.60 53.00 39.75 26.52 18.89 15.91 13.267000 15.610 185.70 92.80 61.90 46.45 30.95 23.20 18.57 15.478500 18.950 225.50 112.80 75.20 56.35 37.60 28.19 22.55 18.7910000 22.250 265.00 132.50 88.30 66.25 44.20 33.15 26.50 22.1014000 31.150 371.00 185.50 123.70 92.75 61.80 46.35 37.10 30.95

1. Acrefoot = 1 acre covered to a depth of 1 ft. = 43,560 cu. ft. / 1.0 cfs (cu. ft./sec.) = 449.5 gpm

Table 1-33: Irrigation - Annual Water Requirement for Selected Crops

Crop * Acre - ft. Crop * Acre - ft. Crop * Acre - ft.

Alfalfa 3 to 4 1/4Almonds 1 3/4 to 2 1/2Barley dryland to 1Beans 1 1/4 to 1 3/4

Beets, Sugar 2 to 3

Cotton 3 to 3 1/2Citrus 2 1/2 to 3Grapes 2 1/2 to 3 1/2

Grain, Sorghums 1 1/2 to 2Orchard, Fruit 2 to 3 1/2

Permanent Pasture 3 to 4 1/2Potatoes 2 3/4 to 3 1/2

Rice 6 to 15Tomatoes 2 to 3Walnuts 3 to 4

* Amounts will vary according to location and climatic conditions. For more precise information, consult yourlocal Farm Advisor. Crops on sandy soils do not need more water than on heavier soils, only more frequentapplications with less water per application.


Section 1


Table 1-34: Irrigation - Application Rates Applied by Overhead Sprinklers (gpm/acre over 24 hours)

Frequency Inches per Irrigation

(days) 1 1 1/2 2 2 1/2 3 4 5 6

7 2.69 4.03 5.37 6.70 8.06 10.75 13.43 16.108 2.36 3.52 4.70 5.88 7.05 9.40 11.75 14.109 2.10 3.14 4.19 5.23 6.28 8.36 10.47 12.5810 1.88 2.82 3.76 4.70 5.65 7.54 9.40 11.30

11 1.71 2.56 3.42 4.27 5.13 6.84 8.55 10.2812 1.57 2.36 3.14 3.92 4.71 6.27 7.85 9.4013 1.45 2.18 2.90 3.62 4.35 5.80 7.25 8.7014 1.35 2.02 2.69 3.36 4.04 5.38 6.73 8.0815 1.26 1.88 2.55 3.14 3.76 5.02 6.28 7.54

16 1.18 1.77 2.36 2.94 3.54 4.71 5.90 7.0617 1.11 1.66 2.22 2.77 3.33 4.44 5.55 6.6518 1.05 1.57 2.09 2.62 3.14 4.18 5.24 6.2819 0.99 1.49 1.98 2.48 2.98 3.97 4.96 5.9520 0.94 1.41 1.88 2.36 2.83 3.77 4.71 5.66

21 0.90 1.35 1.80 2.24 2.69 3.59 4.49 5.3922 0.86 1.28 1.71 2.14 2.57 3.43 4.28 5.1423 0.82 1.23 1.64 2.05 2.46 3.28 4.09 4.9124 0.78 1.18 1.57 1.96 2.36 3.14 3.92 4.7125 0.75 1.13 1.51 1.88 2.26 3.02 3.76 4.52

26 0.72 1.09 1.45 1.81 2.18 2.90 3.62 4.3527 0.70 1.05 1.40 1.75 2.10 2.78 3.49 4.1828 0.67 1.01 1.35 1.68 2.02 2.69 3.36 4.0329 0.65 0.97 1.30 1.62 1.95 2.60 3.25 3.9030 0.63 0.94 1.26 1.57 1.88 2.51 3.14 3.76

Note: 1. For 12 hour operation (12 hr. set), multiply above values by 2 For 8 hour operation (8 hr. set), multiply above values by 3

2. Maximum precipitation rates for overhead irrigation on level ground:Light sandy loam soils - 1.5” to 0.75”/hr. - 679 to 339 gpm/acre.Medium textured clay loam soils - 0.75” to 0.50”/hr. - 339 to 226 gpm/acre.Heavy textured clay soils - 0.50” to 0.20”/hr. - 226 to 90 gpm/acre.

Allowable rates increase with adequate cover and decrease with land slopes.

Table 1-35: Irrigation - Typical Quantity and Frequency Requirements for Various Cropsa

Crop Quantity (in./irrigation) Frequency (days between irrigation)

Pasture 2 - 3 14 - 21Alfalfa 3 - 6 30 - 45Root Crops (carrots, potatoes, etc.) 2 - 3 15 - 30Vegetable (lettuce, beans, etc.) 2 - 3 14 - 21Berries2 - 3 15 - 30Orchards (citrus, stone fruit, etc.) 4 - 6 30 - 60

Note: 1. The number of irrigations required is a function of planting time, growing season and occurrence ofrainfall.

2. In general, 4”/month is considered adequate to grow crops. Irrigation should provide the supplement water crop needs not provided by natural rainfall.

Curves for sizing domestic water demandIs there a need for an alternative to the Hunter curve? Without question there is. The old method of fixture units vs.flow (gpm) has been used for many years as the basis to determine peak water demand for apartment, commercial,and institutional buildings, such as:

• Apartments• Condominiums• Schools• Hospitals• Motels• Hotels• Dormitories

Plumbing system designers have learned through experience that for many applications the Hunter curve isultraconservative. Many have developed, through experience, certain techniques to modify it and bring the designedpeak demand to a more realistic value of actual requirements.

Curves LT1025S through LT1028S, shown on the following pages, are submitted as alternatives to Hunter’s curve.They are based upon metered data, observation, numerous successful installations and other accumulated data fromvarious sources. Each curve is representative of that peak demand normally calculated from fixture units, andextraneous loading, such as cooling tower make-up, restaurant, laundry, health club, etc., must be added to thecurve value. Pay particular attention to the notes with each figure.

Our findings are that no single curve can adequately represent all different usage criteria unless the curve reflectsmaximum values to cover all conditions likely to be encountered, such as the Hunter curve. This type of curve,obviously, will cause gross oversizing in many instances.

On the other hand, values must be adequate to avoid undersigning, and herein lies the question: How much can wereduce the size based on Hunter’s curve? We have found instances where any reduction would cause selection of anundersized system.

The increasing use of water pressure booster systems dictates more efficient operation. Skyrocketing power costs,interest rates, inflation, and other variables make it a necessity to conserve energy. Overdesign is an unaffordableluxury. Too large pumps, motors, and piping increase first cost. Add carrying charges plus energy cost and youhave created an insatiable monster for the life of the installation.

The accompanying curves place additional responsibility on the system designer. No longer should he select asystem with a 20-40-40 percent “split” unless he is prepared to risk inadequate standby capability. Such a systemhas only 60 percent system capability should either of the larger pumps fail. It is recommended that any systemselected from the curves have a minimum residual capacity of 80 percent should any pump fail; two-pump systemsshould have an 80-80 percent split; three-pump systems should have a 25-55-55 percent split, etc. Specific jobconsiderations could change the split. However, these must be analyzed individually.

Note that the only curve using fixture units vs. gpm is Curve LT1028S — schools and dormitories. The values do notconform to those on the Hunter curve, however. All other curves use different criteria to determine flow (gpm):number of dwelling units, square feet of floor space, or number of beds. Refer to the notes on each figure.

Curves LT1025S, Fig. 1-25 and 1-26, provide selection data for six different classes of occupancy. First examinationmay raise questions. However, an in-depth evaluation proves the validity of the curves. The elderly are low waterusers, both from the standpoint of peak demand and total water consumption. High income occupancy reflects lowpeak demand usage but fairly high total water consumption. As income levels fall, density per dwelling unitincreases as does peak demand.


Sect

ion

1



Section 1


In other words, the number of dwelling units, income range, personal habits, mobility, and density are all values toconsider. Peak demand is determined upon the interplay of all these factors. We are not concerned about totalwater usage nor is this a consideration when calculating peak demand.

Curve ➃ in Curves LT1025S, Fig. 1-25 and 1-26, can also be used for hotels and motels (laundry facilities notincluded) by the substitution of the number of rooms for an equal number of apartments. While the total volume ofwater used by the middle income people living in multifamily residential housing will be two or three times that ofhotels/motels, the peak demands are comparable.

Curves LT1026S, 1027S and 1028S — office buildings, hospitals, schools and dormitories — define the qualificationsfor their use on the curves. Note that ➂ on Curve LT1028S may also be used to determine peak demands forstadiums (as qualified).

These curves must be used for reference only.


Sect

ion

1


Figure 1-25: Apartments and Condominiums – Capacity Sizing

40 80 120 160 200 240

350

300

250

200

150

100

50

GALLONS PER MINUTE

NU

MB

ER

OF

UN

ITS

LIQUI-TROL SYSTEMS INC.© LIQUI-TROL SYSTEMS INC. 1980

LT1025S

Apartments and Condominiums

CURVE #1 — Elderly CURVE #4 — Middle IncomeCURVE #2 — High Income CURVE #5 — Low IncomeCURVE #3 — Upper Income CURVE #6 — Public Housing

Curve #4 — Can be used for Motels - Hotels by substitution ofrooms for apartments.

Curve #5 — Can be used for Medical Personnel.

Sizing is based on number of apartments and represents that load usually calculated from fixture units. Extraneous load such as cooling tower make-up, restaurant, etc., must be added.

2

3

4

5

6

1


Section 1


Figure 1-26: Apartments and Condominiums – Capacity Sizing

300 400 500 600 700 800

1280

1120

960

800

640

480

320

160

GALLONS PER MINUTE

NU

MB

ER

OF

UN

ITS


LT1025S

Apartments and Condominiums

2 3 4 5 61


Sect

ion

1


Figure 1-27: Office Buildings – Capacity Sizing

120 240 360 480 600 720

32

28

24

20

16

12

8

4

GALLONS PER MINUTE

SQ

UA

RE

FE

ET

FL

OO

R S

PAC

E


LT1026S

Office Buildings

Sizing is based on square feet of floor space (overall dimensions). Curve represents that demand usually calculated from fixture units. Commercial area is included. Extraneous loads such as cooling tower make-up, restaurant, gang flush systems, etc., must be added.

*Multiply by 105


Section 1


Figure 1-28: Hospitals – Capacity Sizing

100 200 300 400 500 600

800

700

600

500

400

300

200

100

GALLONS PER MINUTE

NU

MB

ER

OF

BE

DS


LT1027S

Hospitals

Sizing is based on number of beds and includes a cafeteria. Extraneous loads such as cooling tower make-up, laundry, etc., are to be added.


Sect

ion

1


Figure 1-29: Schools and Dormitories – Capacity Sizing

100 200 300 400 500 600

9000

8000

7000

6000

5000

4000

3000

2000

1000

GALLONS PER MINUTE

FIX

TU

RE

UN

ITS


LT1028S

Schools and Dormitories

CURVE #1 — Boy's Dormitories CURVE #3 — SchoolsCURVE #2 — Girl's Dormitories

Sizing is based on fixture units. Extraneous loads such as cooling tower make-up, cafeteria, etc., must be added.

Curve #3 can be used for sizing peak demand in stadiums — based on fixture units. Gang-flush systems must be calculated and added.

Before making final size determination we suggest you check with the flush valve manufacturer for maximum flow rate through the valve under design pressure. We recommend continuous flush during peak demand with load calculated accordingly.

2

3

1


Section 1

Section 1E Pumping, Distribution & Storage 1-81

1E PUMPING, DISTRIBUTION & STORAGEAfter water is drawn from the source and treated to bring it up to potable quality, it is carried to consumers througha network of pipes, pumps, and storage tanks; known as the water distribution system. Regular maintenance of thissystem, is essential to ensure a reliable and sanitary supply of water. In planning a new or extending a distributionsystem, longevity and ease of maintenance are important considerations. Installation of the system must beperformed with consideration for worker safety and maintaining sanitary conditions.

Water System Economics. Economics plays an important part in the water supply planning and design process.Design objectives must be clearly established at the outset and the economics associated with service life, cost, easeof expansion, etc., carefully considered. In connection with design, the water consumption (usage) throughout thedesign life must be estimated. Overdesign is not conservative since it may burden a relatively small public watersupply or community unnecessarily. Different segments of water treatment and distribution system may beappropriately designed for differing periods of time using differing capacity criteria. The same issues apply to selfsupplied individual, commercial, industrial and agriculture systems to a verying degree.

The six (6) chief issues associated with water supply facilities planning are outlined below and discussed morethoroughly throughout this manual.

1. Development of source. The design period and service life will depend on the source. For groundwater, if it iseasy to drill additional wells, the design period will be short, perhaps 5 years. The service life for a well typicallyranges from 30 to 40 years depending on materials of construction and ground water quality. The design periodfor surface water supplies can be as much as 50 years. The design capacity of the source should be adequate toprovide the maximum daily demand anticipated during the design period, but not necessarily upon a continuousbasis.

2. Pumping plant. The design period is generally 5 years since modification and expansion are easy if initiallyconsidered. Pump selection requires knowledge of maximum flow and sustainable well yields, including firedemand, average flow, and minimum flow during the design period.

3. Distribution system. The design period is indefinite and the capacity of the system should be sized toaccommodate the maximum anticipated development of the area served. Anticipated population densities, zoningregulations, and other factors affect flow should be considered. Maximum hourly flow including fire demand isthe basis for design.

4. Pipe lines from source. The design period is generally long since the life of pipe is long and the cost of materialis only a portion of the cost of construction. Twenty-five years or more would not be unusual. The designcapacity of the pipe with consideration being given to provision of suitable velocities under all anticipated flowconditions.

5. Amount of storage. The design period may be influenced by cost factors peculiar to the construction of storagevessels, which dictate a minimum unit cost for a tank of specific size. Design requires knowledge of averageconsumption, fire demand, maximum hour, maximum week, and maximum month, as well as the capacity of thesource and pipe lines from the source.

6. Water supply treatment. The design period is generally short since expansion is generally simple if it isconsidered in the initial design. Most treatment processes are designed for average daily flow. Water treatment isnormally a small portion of a groundwater supply source.

Water source development and treatment issues as described above in items 1 and 6, are discussed in Section 1Band 1C respectively. The other water supply topics (items 2-5) are reviewed and discussed later on.

PumpingPumps in a small utility are used to draw water from the source and move it through the distribution system. Insome utilities, a single pump at the well may be the only pump required. Other system may have booster pumps tomove water and maintain distribution pressure within the distribution system. Large municipal utilities have complexnetworks of pump installations, often controlled and monitored from a central location. The power cost associatedwith pumping is often one of a utility’s major annual budget items, making the selection of efficient and reliablepumping equipment an important issue.


Sect

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1

Section 1E Pumping, Distribution & Storage1-82

Types of Water Well Pumps. Three types of pumps are commonly used in small water supply and distributionsystems. They are; (1) positive displacement pumps, (2) centrifugal pumps - which include submersible and turbinetypes, and (3) jet pumps. Positive displacement and jet pumps are generally of limited capacity and so not representa significant portion of the pumps used in the public water supply industry. Positive displacement pumps areoutside the scope of this manual and are not addressed.

Well pumps can be further classified as deep or shallow well pumps. Pumps which rely on suction lift are generallyconsidered shallow well pumps. Deep well pumps generally rely on the positive submergence of the pumpingelement.

Centrifugal Pumps. Centrifugal pumps contain a rotating impeller mounted on a shaft turned by the powersource. Water enters the center of the rotating impeller and is thrown outward at high velocity into a surroundingcasing shaped to slow down the water flow by converting the velocity into pressure. A centrifugal well pumpoverview is presented in Table 1-36.

Each impeller and matching casing is called a stage. When the pressure is more than can be practicably oreconomically furnished by a single stage, additional stages are used. A pump with more than one stage is called amultistage pump. In a multistage pump water passes through each stage in succession, with an increase in pressureat each stage. Multistage pumps commonly used in individual water systems are of the turbine and/or submersibletypes. The number of stages necessary for a particular installation is determined by the pressure needed for theoperation of the water system and the height the water must be raised from the surface of the water source.

Turbine pumps. The vertical turbine pump consists of one or more centrifugal pump stages with the pumping unitlocated below the drawdown level of the water source. A vertical shaft connects the pumping assembly to a drivemechanism located above the pumping assembly. The discharge casing, pump housing , and inlet screen aresuspended form the pump base at the ground surface. The weight of the rotating portion of the pump is usuallysuspended by a thrust bearing located in the pump head. The intermediate pump bearings may be lubricated byeither oil or water. Lubrication of pump bearings by water is preferable, since lubricating oil may leak andcontaminate the water.

Submersible pumps. A centrifugal pump driven by a closely coupled electric motor constructed for submergedoperation as a single unit is called a submersible pump. The electrical wiring to the submersible motor must bewaterproof, and the electrical control should be properly grounded to minimize the possibility of shorting anddamaging the entire unit. The pump and motor assembly are supported by the column (drop pipe).

The submersible pump forces water directly into the distribution system; therefore, the pump assembly must belocated below the maximum drawdown level. This type of pump can deliver water across a wide range ofpressures and flows, with the only limiting factor being the size of the unit and the horsepower applied. When sandis present or anticipated in the water source, special precautions should be taken before this type of pump is used,since the abrasive action of the sand during pumping will shorten the pump’s life.

Jet Pumps. Jet pumps can be supplied in a deep well or shallow well configuration. The shallow well jet pumprelies completely on suction lift created by a surface or internal ejector assembly. The deep well jet pump requiresthat the ejector be mounted submerged within the well. In the deep well configuration, a portion of the dischargedwater from the centrifugal pump is diverted through a nozzle and venturi tube located near the water level of thesource (usually a well). Because a pressure zone lower than that of the surrounding area exists in the venturi tube,water from the source flows into this area of reduced pressure. The velocity of the water the nozzle pushes itthrough the pipe toward the surface where the centrifugal pump can lift it by suction.

Shallow well jet pumps differ from shallow well centrifugals in that suction lift is created by ejector (venturi) action.Jet pumps generally have greater lift capabilities than centrifugals. In both the deep and shallow well configuration,the centrifugal action of the pump forces water into the distribution system. Jet pumps are usually economical forlow-volume/shallow water level installations.


Section 1


Tab

le 1

-36

: C

en

trif

ug

al

Pu

mp

Ove

rvie

w f

or

Wa

ter

We

ll A

pp

lic

ati

on

Typ

e o

f P

um

p

Cen

trif

uga

l:1.

Shal

low

wel

l

2. D

eep w

ell

a. V

ertic

al lin

e sh

aft

turb

ine

(multi

-sta

ge)

b. Su

bm

ersi

ble

turb

ine

(multi

-sta

ge)

Jet:

1. S

hal

low

wel

l

2. D

eep w

ell

Pra

ctic

al

Suct

ion

Lif

t

15 f

t. (5

m)

Impel

ler

subm

erge

d

Pum

p a

nd m

oto

rsu

bm

erge

d.

15-2

2 ft. (5

-7 m

)

15-2

2 ft. (5

-7 m

)

Usu

al W

ell-

Pu

mp

ing

Dep

th

3-15

ft.

(1-5

m)

50-5

00 f

t. (1

5 -

150

m)

typic

al

1,00

0 ft. se

ttin

gpra

ctic

al lim

it

15 -

22

ft.

(5 -

7 m

)

25 -

120

ft.

(8-3

7 m

) 20

0 ft.

(61

m)

max

.

Usu

al P

ress

ure

Hea

ds

80-1

50 f

t. (2

4-46

m)

100

- 80

0 ft.

(30

- 24

5m)

100

- 80

0 ft.

(30

- 24

5m)

80 -

150

ft.

(24

- 46

m)

80 -

150

ft.

(24

- 46

m)

Ad

van

tage

s

• S

mooth

, ev

en flo

w •

Hig

h r

elia

bili

ty •

Open

or

close

d im

pel

ler

des

igns

avai

lable

•Can

be

use

d a

s a

boost

er p

um

p.

• P

roduce

s sm

ooth

,ev

en f

low

• A

llel

ectric

al c

om

ponen

tsar

e ac

cess

ible

, ab

ove

ground •

Hig

hef

fici

ency

.

• P

roduce

s sm

ooth

,ev

en f

low

• E

asy

tofrost

-pro

of

inst

alla

tion

• S

hort p

um

p s

haf

t to

moto

r • Q

uie

toper

atio

n •

Wel

lst

raig

htn

ess

not cr

itica

l• V

andal

res

ista

nt.

Hig

h c

apac

ity a

t lo

whea

ds.

Sim

ple

in

oper

atio

n. D

oes

not

hav

e to

be

inst

alle

dove

r th

e w

ell.

Sam

e as

shal

low

wel

lje

t. W

ell st

raig

htn

ess

not cr

itica

l.

Dis

adva

nta

ges

Lose

s prim

e ea

sily

Effic

iency

dep

ends

on

oper

atin

g under

des

ign

hea

d a

nd s

pee

d.

Req

uires

strai

ght w

ell

larg

e. L

ubrica

tion a

nd

alig

nm

ent of

shaf

tcr

itica

l. Abra

sion f

rom

sand.

Rep

air

to m

oto

r or

pum

p r

equires

pulli

ng

from

wel

l. Se

alin

g of

elec

tric

al e

quip

men

tfrom

wat

er c

ritic

al.

Abra

sion f

rom

san

d.

Cap

acity

red

uce

s as

lift

incr

ease

s. A

ir in

suct

ion o

r re

turn

lin

ew

ill s

top p

um

pin

g.

Sam

e as

shal

low

wel

lje

t. Lo

wer

effic

iency

,es

pec

ially

at gr

eate

rlif

ts.

Rem

ark

s

Sim

ilar

to jet

pum

p b

ut

does

not re

quire

inte

rnal

jet

nozz

le o

rej

ecto

r fo

r su

ctio

n lift.

Usu

ally

pro

vided

in

horizo

nta

l co

nfigu

ratio

n

1800

rpm

model

snorm

ally

use

d f

or

wat

erw

ell ap

plic

atio

ns.

150

ft.

max

. se

ttin

g @

360

0rp

m.

3500

RPM

model

s m

ost

popula

r bec

ause

of

smal

ler

dia

met

ers

and

hig

h c

apac

ity, ar

e m

ore

vuln

erab

le to w

ear

and

failu

re f

rom

san

d a

nd

oth

er c

ause

s. 1

800

rpm

model

s av

aila

ble

.

Cer

tain

man

ufa

cture

rsan

d m

odel

s w

illove

rload

if

use

d f

or

boost

er s

ervi

ce.

The

amount of

wat

erre

turn

ed to e

ject

or

incr

ease

s w

ith incr

ease

dlif

t -

50%

of

tota

l w

ater

pum

ped

at 50

ft.

(15

m)

lift an

d 7

5% a

t 10

0 ft.

(30

m)

lift.


Sect

ion

1


Selection of Pumping Equipment. The type of pump selected for a particular installation should be determinedon the basis of the following fundamental considerations:

• Yield of the well or water source.• Daily needs and instantaneous demand of the system.• The usable water in the pressure or storage tank.• Size and alignment of the well casing.• Total operating head pressure of the pump at normal delivery rates, including lift and all friction losses.• Difference in elevation between ground level and water level in the well during pumping.• Availability of power.• Ease of maintenance and availability of replacement parts.• First cost and economy of operation.• Reliability of pumping equipment.

The rate of water delivery required depends on the time of effective pump operation as related to the total waterconsumption between periods of pumping. Determining total water use is discussed in Section 1D. The period ofpump operation depends on the quantity of water on hand to meet peak demands and the storage available. If thewell yield permits, a pump capable of meeting the peak demand should be used.

When the well yield is low in comparison to peak demand requirements, an appropriate increase in the storagecapacity is required. The life of an electric-drive motor will be reduced when there is excessive starting andstopping. The water system should be designed so that the interval between starting and stopping is as long aspracticable. Generally, high capacity pumps should not start and stop more than four to five times per hour (6 times- max).

Shallow well pumps, which operate based on suction lift should be installed with a foot valve at the bottom of thesuction line or with a check valve in the suction line in order to maintain pump prime. The selection of a pump forany specific installation should be based on competent advice. Factory representatives of pump manufacturers andconsulting engineering firms are often qualified to provide application and installation information.

Sanitary Protection of Pumping Facilities. The pump equipment should be constructed and installed so as toprevent contamination or objectionable material from entering the well or the water that is being pumped. Thefollowing factors should be considered:

• Design the pump head (well head) or enclosure so as to prevent pollution of the water by lubricants or othermaintenance materials used during operation of the equipment. Pollution from hand contact, dust, rain, animalsor insects, and similar contaminates should be prevented from reaching the water in take of the pump or thesource of supply.

• Designing the pump base or enclosure so as to facilitate the installation of a sanitary well seal within the wellcover or casing.

• Design for frost protection, including pump drainage within the well as necessary.• Overall design consideration so as to best facilitate necessary maintenance and repair, including overhead

clearance for removing the drop (column) pipe and other accessories.

When planning for sanitary protection of a pump, each installation must be considered on a case by case basses.See Figure 1-20 for typical submersible well head completions.

Check Valves. A check valve between the pump and storage should be located within the well or at least upstreamfrom any portion of a buried discharge line. This will ensure that the discharge line at any point where it is incontact with soil or a potentially contaminated medium will remain under positive system pressure, whether or notthe pump is operating. There should be no check valve at the inlet to a pressure tank or elevated storage tank. Thisrequirement does not apply to a concentric piping system, with the external pipe constantly under system pressure.Some pumps (submersibles, jets) often have a check valve installed within the well.


Section 1


Well Vents. A well vent is recommended on all wells except for special applications. The vent prevents a partialvacuum inside the well casing as the pump lowers the water level in the well. The well vent, whether built into thesanitary well cover or conducted to a point remote from the well, should be protected from mechanical damage;have watertight connections; and be resistant to corrosion, vermin, and rodents.

The opening of the well vent should be located not less than 24 in. (610 mm) above the highest known flood level.It should be screened with durable, corrosion-resistant material or otherwise constructed so that openings excludeinsects and vermin. Well vent requirements may be subject to specific regulation requirements.

Miscellaneous. It is desirable to provide a water-sampling tap in the pump discharge line. The sampling tap shouldbe modified to exclude the tap from being used for no other purpose than sampling.

Installation of Pumping Equipment. Where and how the pump and motor are mounted depend primarily on thetype of pump used. The vertical turbine centrifugal pump, with motor mounted directly over the well and thepumping assembly submerged within the well, is gradually being replaced by the submersible unit, with both theelectric motor and the pump submerged within the well. Similarly, the jet pump is gradually giving way to thesubmersible pump, especially for deeper installations, because of the latter’s inherently superior performance andbetter operating economy.

A minimum annular clearance of 0.75 inches (1.5 inches overall) is recommended between the well casing and themaximum diameter of the largest down hole component of the pump string. If there is any doubt about whetherthere is enough room for the pump, a piece of pipe with dimensions slightly greater than those of the pump shouldfirst be run through the casing to make sure that the pump will pass freely to the desired depth of setting. It isrecommended that all wells be equipped with an access pipe in to the well, independent of the well seal to allowmeasuring devices to be easily inserted and withdrawn into the well. The remote access pipe permits chemicaltreatment of the well without removing the sanitary well seal and pump.

Vertical Turbine Installations. In the vertical turbine pump installation, the power unit (usually an electric motor) isinstalled directly over the well casing. The pump portion is submerged within the well, and the two are connectedby a shaft enclosed within the pump column. The pump column supports the bearing system for the drive shaftand conducts the pumped water to the surface.

Submersible Installations. Because all moving parts of a submersible pump are located within the well in a unit, thispump can perform well in casings that might be to crooked for vertical turbine pumps.

The entire weight of the pump, cable, drop pipe, column of water within the pipe, and reaction load whenpumping must be supported by the column pipe. It is important that the column pipe and couplings be of goodquality materials suitable for the service and tensile load. A torgue arrestor should be considered if plastic pipe ofhose is used for low capacity/shallow installations. Cast-iron fittings should not be used where they must support atensile load. The entire load of submersible pumping equipment is normally suspended form the sanitary well sealor cover. An exception to this would be the pitless installation (Figure 1-31).

Jet Pump Installations. Jet pumps may be installed directly over the well or alongside the well. Since there areno moving parts in the well, straightness and plumpness do not affect the jet pump’s performance. The weight ofequipment in the well is relatively small, being mostly pipe (often plastic), so that loads are supported easily by thesanitary well seal. There are also a number of good pitless adapter and pitless unit designs for both single anddouble-pipe jet systems.

Pumping Plants and Appurtenances for Submersible Applications. Pumping plants and supporting structuresshould be installed above ground. Structural floor system should be of watertight construction, preferable concrete,and should slope uniformly away in all directions from the well casing or pipe sleeve. all structures should be offire proof construction, pleasing in appearance, well lighted, easy to clean and serviceable. Electrical equipmentshould be housed in appropriate enclosure type for the service. Well sites/pumping plants should be designed foryear round access. In cold climates, it should not be necessary to use an underground discharge connection if aninsulted, heated pumphouse is provided. A pitless adapter can be used if a pumphouse facility is not practical.


Sect

ion

1


In areas where power failure may occur, an emergency generator power supply should be considered. A naturaldisaster (severe storm, hurricane, tornado, blizzard, or flood) may cut off power for hours or even days. A electricalgenerator is often used to supply the power requirements of the pump, basic lighting, cooling, and otheremergency needs.

Lightning Protection. Voltage and current surges produced in powerlines by lightning discharges are a seriousthreat to electric motors. The high voltage can easily perforate and burn the insulation between motor windings andmotor frame. The submersible pump motor is more vulnerable to this kind of damage because it is submerged ingroundwater-the natural “ground”, making lightning protection a serious issue for submersible pumps in electricalstorm prone areas. Actual failure of the motor may be immediate or it may be delayed for weeks or months.

Simple lightning arresters are available to protect motors and appliances from “near miss” lightning strikes. (Theyare seldom effective against direct hits.) The two types available are the valve type and the expulsion type. Thevalve type is preferred because its “sparkover” voltage remains constant with repeated operation. Just as importantas selecting a good arrester is installing it properly.

Figure 1-30: Annual Frequency of Electrical Storms in the U.S.

Pitless Adapters. Because of the pollution hazards involved, a well pit to house the pumping equipment or topermit accessibility to the top of the well is not recommended. A commercial unit know as a pitless adaptereliminates well-pit construction. A specially designed connection between the underground horizontal dischargepipe and the vertical casing pipe makes it possible to terminate the permanent, watertight casing of the well at asafe height (8 in. or more) above the final grade level. The underground section of the discharge pipe ispermanently installed, and it is not necessary to disturb it when repairing the pump or cleaning the well. There arenumerous makes and models of pitless adapters available. Refer to Figure 1-31 for a illustration of the variouspitless adapter applications.


Section 1


Figure 1-31: Typical Submersible Pitless Adapter Units

* Courtesy of Monitor, a division of Baker Mfg. Co.

Distribution LinesThe pipes, valves, and fittings that distribute treated water to a community comprise a large part of a utility’s capitalworth. These distribution lines require relatively little maintenance, but their initial selection should take intoaccount local water and soil conditions to ensure long life. Periodic monitoring of distribution line condition isadvisable to check for conditions of corrosion or scaling.

Pipe and Fittings. For economic reasons and ease of construction, distribution lines for small water systems areordinarily constructed of plastic. Other common types of pipes used are steel and ductile cast iron. Under certainconditions and in certain areas, where metallic piping is used, it may be necessary to use protective coatings,galvanizing, or have the pipes dipped or wrapped. When corrosive water or soil is encountered, the use of plasticis generally more cost effective.

Plastic pipe for cold-water piping is usually simple to install, has a low initial cost and has good hydraulicproperties. When used in a potable water system, plastic pipe should be certified by an acceptable testinglaboratory (such as the National Sanitation Foundation-NSF) as being nontoxic and non-taste producing. It shouldbe protected against crushing by proper trench bedding and from attack by rodents.

Fittings are usually available in the same sizes and materials as piping; valves are generally cast iron, bronze orother alloys. In certain soils the use of dissimilar metals in fittings and pipe may create electrolytic corrosionproblems. The use of nonconductive plastic inserts between pipe and fittings or the installation of sacrificial anodeshelps to minimize such corrosion.

Standard Custom Booster

Pipes should be laid in trenches as straight as possible. Air-relief valves or hydrants should be located at the highpoints on the line. Failure to provide for the release of accumulated air in a pipeline on hilly ground may greatlyreduce the capacity of the line. It is necessary that pipeline trenches be excavated deep enough to prevent freezingin the winter. Pipes placed in trenches at a depth of more than 3 ft (1m) will help to keep the water in the pipelinecool during the summer months. A 10 to 15 degree F change between summer and winter distribution temperatureis not unusual.

Pipe Capacity and Head Loss. Any pipeline selected should be able to deliver the required peak flow withoutexcessive loss of head-without decreasing the discharge pressure below a desirable minimum. The normal operatingwater pressure for household or domestic use ranges from 20 to 60 psi at the fixture.

Pipe line velocities at maximum flow should not exceed 6 ft/s (2 m/s). A design values of 3ft/s (1 m/s) iscustomarily used at the average flow rate anticipated for the main.

Pipeline capacity is determined by its size, length, and interior surface condition. Assuming the length of the pipe isfixed and its interior condition established by the type of material, the usual problem in design of a pipeline isselecting the required diameter. Refer to Section 7 for piping friction loss data.

Additional head losses may be expected from the inclusion of valves and fittings in the pipeline. These losses maybe expressed in terms of equivalent length of pipe, which would produce an equivalent loss. Fitting losses are notparticularly important for fairly long and low velocity pipelines (length > 300 and velocity < 3 ft./sec.). Fitting lossesare very important in short complicated piping network and have a direct bearing system performance. Refer toSection 7 for fitting friction loss/equivalent length data.

Protection of Distribution Systems. Sanitary protection of new or repaired pipelines can be facilitated by properattention to certain details of construction. All connections should be made under dry conditions, either in a drytrench or, if it is not possible to completely dewater the trench, above the ground surface. Soiled piping should bethoroughly cleaned and disinfected before connections are made. Flush valves or clean outs should be provided atlow points where there is no possibility of flooding. Before a distribution system is placed into service it should becompletely flushed, disinfected, and tested for bacteriological quality. There should be no cross-connection, bypass,or other piping arrangement whereby polluted water or water of questionable quality can be discharged or drawninto the domestic water-supply system.

Disinfection of a Water Distribution System. Disinfection of water distribution piping, tanks, pumps andassociated devices are required before placing a system into service. Disinfection is required under the followingnormal operating conditions.

• Disinfection of a system that has been in service using raw or polluted water, preparatory to transferring theservice to treated water.

• Disinfection of a new system on completion and preparatory to placing in operation with treated water or waterof satisfactory quality.

• Disinfection of a system after completion of maintenance and repair operations

The entire system should be thoroughly flushed with water to remove any sediment that may have collected duringconstruction, maintenance or operation. The system should then be filled with a disinfecting solution ofhypochlorite and treated water. This solution is prepared by adding 1.2 lb (0.5kg) calcium hypochlorite (70%available chlorine) to each 1000 gal (3800L) of water or by adding 2 gal (8L) of ordinary household liquid bleach toeach 1000 gal of water. A mixture of this kind provides a solution having not less than 100 mg/L of availablechlorine.

The disinfectant should be retained in the system if possible for not less than 24 hours, examined for residualchlorine, and drained out. If no residual chlorine is present, the process should be repeated. The system is thenflushed with treated water and put into operation. More detailed procedures for disinfection of tanks and mains arelisted in American Water Works Association (AWWA) standards.


Sect

ion

1



Section 1


StorageStorage facilities are necessary so source pumping and treatment facilities can be sized and operated at an averagerate, rather than being operated at a peak rate for a few hours each day and running at far less than maximumcapacity for the remainder of the day. Where ground water sources are used that have sufficient capacity andrequire little treatment, only a small artificial storage facility may be needed. Approximation used by water systemdesigners to estimate usable storage are listed as follows:

1. 2-5 gallons storage for every 10 gpm capacity (small system-capacity adequate to meet peak flow)2 2 times the average summer daily consumption (small system-capacity insufficient to meet peak flow)3. 15 to 30% of the maximum daily use (large system-adequate capacity)

Actual storage requirements are highly dependent on system capacity, fire flow requirements, availability ofemergency power and system operational scheme. Four types of storage facilities are commonly used for smallwater-supply systems. They are ground-level tanks (reservoirs), elevated storage tanks, pressure tanks and aquiferstorage.

Ground-level tanks (reservoirs): Ground level tanks are simple to construct and maintain. They can be locatedon a hill with sufficient elevation so as to provide adequate system pressure, or they can configured to collect waterpumped from wells for boosting into the distribution system. See Table 1-37 for storage capacity for variousrectangular and round tank configurations.

Elevated storage: The major advantage of elevated storage tanks is that not only do they hold water in storage, theyalso hold it at a height that maintains pressure to the distribution system without the need for continuous pumping.The height needed for an elevated tank can be calculated as 2.31 times the required system pressure in psig. Forexample, a system pressure of 60 psig can be supplied by a tank 139 ft high (measured from the ground to the waterlevel in the tank). Areas prone to siesmic events are less likely to utilize elevated storage in new construction.

Pressure tanks: Pressure in a distribution system served by a hydro-pneumatic tank is maintained by pumpingwater directly to the tank from the source. This pumping action compresses a volume of entrapped air. The airpressure is equal to the water pressure in the tank and can be controlled between desired limits by means ofpressure switches, which stop the pump at the maximum setting and start it at the minimum setting. Pressure tanksare normally designed to meet only peak demands and prevent excessive pump cycling. Only 10-40 percent of tankvolume is usable for storage.

Hydro-pneumatic systems are most commonly used for small water systems and self supplied commercial industrialfacilities. Tank selection is a function of several factors; such as population, well capacity and regulatory policy. The“Ten-State Standards” selection guide lines for pressure tanks are listed as follows:

• Hydro-pneumatic systems should not be used to serve more than 150 living units.• Pressure tank storage should not be considered for fire protection purposes.• The tank should be located above normal ground surface and be completely housed where required by climate.• The capacity of the wells and pumps serving the system should be at least ten times the average daily

consumption rate.• The gross volume of the tank (in gallons) should be at least ten times the capacity of the largest pump, rated in

gallons per minute (for example, if the largest pump produces 250 gpm, the tank should hold at least 2,500gallons).

• Where practical, the access manhole should be 24” in diameter.

The exact requirements for the water system are determined by the regulatory agency having jurisdiction.

Aquifer storage: In areas where high capacity water well are possible to construct, traditional storage techniqueshave given way to aquifer storage. Well pumps are controlled by varidable frequency drives (VFD’s) which maintainconstant system pressure by increasing or decreasing pump speed in response to demand. Wells and pumps aredesigned to meet the peak system and fire flows requirements with the aquifer acting as the supply and storagereservoir.


Sect

ion

1


Automatic transfer of emergency generator power to pumping equipment eliminates the need for significant systemstorage to supply water during abnormal operating conditions. Minimal buffer storage is generally required withinthe system for efficient operation.

Protection of Storage Facilities. Suitable storage facilities for relatively small systems may be constructed ofconcrete, plastic or steel for above or below ground applications. All storage tanks for domestic water supplyshould be completely covered. They should be constructed and located so as to prevent pollution of the tankcontents by outside water or other foreign matter.

All tanks require adequate screening of any openings to protect against entrance of small animals and insects. Watersupply, distribution and storage facilities should be secured and locked to prevent access by unauthorized persons.

The water in storage tanks or pipelines should not be contaminated with an emergency water supply that has notbeen treated prior to transmission. Disinfection of storage facilities after construction, repair or maintenance shouldbe carried out in accordance with the recommendations noted in Section 1C.


Section 1


Tab

le 1

-37

: C

ap

ac

ity

of

Re

cta

ng

ula

r S

tora

ge

Ta

nk

s in

ga

l./f

t. o

f d

ep

th

Wid

th o

fT

ank

(ft

.)

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

344

.88

56.1

067

.32

***

***

***

***

***

***

***

***

***

***

***

***

***

***

***

***

***

***

3.5

52.3

665

.45

78.5

491

.64

***

***

***

***

***

***

***

***

***

***

***

***

***

***

***

***

***

459

.84

74.8

089

.77

104.

7311

9.69

***

***

***

***

***

***

***

***

***

***

***

***

***

***

***

***

4.5

67.3

284

.16

100.

9911

7.82

134.

6515

1.48

***

***

***

***

***

***

***

***

***

***

***

***

***

***

***

574

.81

93.5

111

2.21

130.

9114

9.61

168.

3118

7.01

***

***

***

***

***

***

***

***

***

***

***

***

***

***

5.5

82.2

910

2.86

123.

4314

4.00

164.

5718

5.14

205.

7122

6.28

***

***

***

***

***

***

***

***

***

***

***

***

***

689

.77

112.

2113

4.65

157.

0917

9.53

201.

9722

4.41

246.

8626

9.30

***

***

***

***

***

***

***

***

***

***

***

***

6.6

97.2

512

1.56

145.

8717

0.18

194.

4921

8.80

243.

1126

7.43

291.

7431

6.05

***

***

***

***

***

***

***

***

***

***

***

710

4.73

130.

9115

7.09

183.

2720

9.45

235.

6326

1.82

288.

0031

4.18

340.

3636

6.54

***

***

***

***

***

***

***

***

***

***

7.6

112.

2114

0.26

168.

3119

6.36

224.

4125

2.47

280.

5230

8.57

336.

6236

4.67

392.

7242

0.78

***

***

***

***

***

***

***

***

***

811

9.69

149.

6117

9.53

209.

4523

9.37

269.

3029

9.22

329.

1435

9.06

388.

9841

8.91

448.

8347

8.75

***

***

***

***

***

***

***

***

8.6

127.

1715

8.96

190.

7522

2.54

254.

3428

6.13

317.

9234

9.71

381.

5041

3.30

445.

0947

6.88

508.

6754

0.46

***

***

***

***

***

***

***

913

4.65

168.

3120

2.97

235.

6326

9.30

302.

9633

6.62

370.

2840

3.94

437.

6047

1.27

504.

9353

8.59

572.

2560

5.92

***

***

***

***

***

***

9.5

142.

1317

7.66

213.

1924

8.73

284.

2631

9.79

355.

3230

0.85

426.

3946

1.92

497.

4553

2.98

568.

5160

4.05

639.

5867

5.11

***

***

***

***

***

10

149.

6118

7.01

224.

4126

1.82

299.

2233

6.62

374.

0341

1.43

448.

8345

6.23

523.

6456

1.04

598.

4463

5.84

673.

2571

0.65

748.

05**

***

***

***

*

10.5

157.

0919

6.36

235.

6327

4.90

314.

1835

3.45

392.

7243

2.00

471.

2751

0.54

549.

8158

9.08

628.

3666

7.63

706.

9074

6.17

785.

4582

4.73

***

***

***

11

164.

5720

5.71

246.

8628

8.00

329.

1437

0.28

411.

4345

2.57

493.

7153

4.85

575.

9961

7.14

658.

2869

9.42

740.

5678

1.71

822.

8686

4.00

905.

14**

***

*

11.5

172.

0521

5.06

258.

0730

1.09

344.

1038

7.11

430.

1347

3.14

516.

1555

9.16

602.

1864

5.19

688.

2073

1.21

774.

2381

7.24

860.

2690

3.26

946.

2798

9.29

***

12

179.

5322

4.41

269.

3031

4.18

359.

0640

3.94

448.

9349

3.71

538.

5958

3.47

628.

3667

3.24

718.

1276

3.00

807.

8985

2.77

897.

6694

2.56

987.

4310

32.3

1077

.2

Len

gth

of

Tan

k (

ft.)

Tab

le 1

-38

: C

ap

ac

ity

of

Ro

un

d S

tora

ge

Ta

nk

s

Ver

tica

l Tan

kD

ia.

Vo

l.A

rea

Dia

Vo

l.A

rea

Dia

.V

ol.

Are

aD

ia.

Vo

l.A

rea

(ft.

)(g

al./

ft.)

(sq

. ft

.)(f

t.)

(gal

./ft

.)(s

q.

ft.)

(ft.

)(g

al./

ft.)

(sq

. ft

.)(f

t.)

(gal

./ft

.)(s

q.

ft.)

1.00

5.87

.785

5.50

177.

7223

.76

10.0

058

7.52

78.5

419

.00

2120

.90

283.

531.

259.

181.

227

5.75

194.

2525

.97

10.5

064

0.74

86.5

919

.50

2234

.00

298.

651.

5013

.22

1.76

76.

0021

1.51

28.2

711

.00

710.

9095

.03

20.0

026

50.1

031

4.16

1.75

17.9

92.

405

6.25

229.

5030

.68

11.5

077

6.99

103.

8721

.00

2591

.00

346.

362.

0023

.50

3.14

26.

5024

8.23

33.1

812

.00

846.

0311

3.10

22.0

028

43.6

038

0.13

2.25

29.7

43.

976

6.75

267.

6935

.78

12.5

091

8.00

122.

7223

.00

3108

.00

415.

482.

5036

.72

4.90

97.

0028

7.88

38.4

813

.00

992.

9113

2.73

24.0

033

84.1

045

2.39

2.75

44.4

35.

940

7.25

308.

8141

.28

13.5

010

70.8

014

3.14

25.0

036

72.0

049

0.87

3.00

52.8

87.

069

7.50

330.

4844

.18

14.0

011

51.5

015

3.94

26.0

039

71.6

053

0.93

3.25

62.0

68.

296

7.75

352.

8847

.17

14.5

012

35.3

016

5.13

27.0

042

83.0

057

2.66

3.50

71.9

79.

621

8.00

376.

0150

.27

15.0

013

21.9

017

6.71

28.0

046

06.2

061

5.75

3.75

82.6

211

.045

8.25

399.

8853

.46

15.5

014

11.5

018

8.69

29.0

049

41.0

066

0.52

4.00

94.0

012

.566

8.50

424.

4856

.75

16.0

015

04.1

020

1.06

30.0

052

87.7

070

6.86

4.25

106.

1214

.186

8.75

449.

8260

.13

16.5

015

99.5

021

3.82

31.0

056

46.1

075

4.77

4.50

118.

9715

.90

9.00

475.

8963

.62

17.0

016

97.9

022

6.98

32.0

060

16.2

080

4.25

4.75

132.

5617

.72

9.25

502.

7067

.20

17.5

017

99.3

024

0.53

33.0

063

94.8

785

4.87

5.00

146.

8819

.63

9.50

530.

2470

.88

18.0

019

03.6

025

4.47

34.0

067

88.2

790

7.46

5.25

161.

9321

.65

9.75

558.

5174

.66

18.5

020

10.8

026

8.80

35.0

071

93.4

596

1.63

Ho

rizo

nta

l Tan

kD

epth

Rat

io%

of

tota

l(%

fil

led

)V

olu

me

.1 (

10%

)5.

22

.2 (

20%

)14

.2

.3 (

30%

)26

.2

.4 (

40%

)37

.4

.5 (

50%

)50

.0

.6 (

60%

)62

.6

.7 (

70%

)73

.8

.8 (

80%

)85

.8

.9 (

90%

)94

.8

.10

(100

%)

100.

0

Note

:1.

To f

ind the

capac

ity o

f ta

nks

gre

ater

than

the

larg

est gi

ven in the

table

, lo

ok

in the

table

for

a Ta

nk

of

one-

hal

f th

e gi

ven s

ize

and m

ulti

ply

its

cap

acity

by

4.2.

The

above

ref

eren

ced f

igure

s ar

e bas

ed o

n f

lat ta

nk

ends.

The

actu

al v

olu

me

of

the

tank

with

curv

ed/d

ished

ends

will

be

som

ewhat

gre

ater

.3.

The

volu

me

in c

u. ft. = A

rea

in s

q. ft f

or

1.0

ft. of

dep

th.


Sect

ion

1

Hydro-Pneumatic SystemsThe hydro-pneumatic (pressure tank) system is a means of meeting varying water needs within a stable pressurerange. A properly designed hydro-pneumatic system will minimize pump cycling, and provide continuous andadequate supply of water to all connections in the system.

The key components of a hydro-pneumatic system are the pump, pressure switch, tank and air volume controls. Forthe purpose of this discussion, all references will apply primarily to the use of submersible pumps and public watersystems. Slightly different requirements may be required for shallow well centrifugal, jet and vertical turbine pumps.

Hydro-pneumatic storage is normally considered buffer storage and should not be counted on to supplement peakdemand lasting longer than 10 minutes or fire protection. The water supply must be capable of meeting peakdemand on its own, if no intermediate storage is provided. Pressure tanks are normally constructed of steel and aremost commonly rated for a working pressure of 100 psi (125 and 150 psi ratings available). Precharged diaphragmand bladder type tanks are not commonly employed by public water systems.

In a hydro-pneumatic system, a quantity of water compresses a quantity of air. It is this air pressure (stored energy)which forces water through the system. Air is a gas and can be compressed; the pressure being related to thevolume of space occupied by the air according to Boyle’s law

Thus, if pressure A is 10 psi and volume of space it occupies is 100 cubic inches (volume of space A), then toreduce the pressure to 5 psi (pressure B), the volume of space B must be increased to 200 cubic inches. This is trueonly if the temperature of the air remains constant. In practice, this temperature effect can be ignored in theaverage hydro-pneumatic water system.

Forcing water into the tank compresses the air remaining. As water is removed (drawdown storage), this airexpands and reduces in pressure until it reaches a point where the pressure is too low to force out any more water.The water remaining is unusable and cannot be considered storage capacity.

A typical hydro-pneumatic system utilizing a submersible pump is shown in Figure 1-32.

System Design.Step 1. Determine the maximum demand of water. Refer to Section 1D for estimating demand for variousapplications.

Step 2. Determine the minimum tank pressure allowable in psi (P tank min.) needed in the system. This is the sumof:

a) Minimum allowable system pressure in psi (P min) at the highest and/or the most distant point from the tank.

b) Vertical height in feet (Hv) of the highest and/or the most distant point form the tank.

c) Pressure drop (head loss) in the length of pipe to reach highest and/or the most distant connection from the tank. The head loss (Hl) value in feet should be based on the average flow out of the tank for large systems and peak flow for small system at the average tank pressure. Refer to Section 7 for estimating pipefriction losses (Hl).

This information will establish the minimum pressure needed in the tank at all times to supply the system needs. Theselection of the high pressure point is limited by safety considerations and has a definite effect on the efficient use ofthe tank, as well as the usable storage. The usable storage capacity for a given size tank decreases with an increase


P tank min. = P min + Hv /2.31+ Hl/2.31

Pressure A = Volume of Space BPressure B = Volume of Space A

=


Section 1

Section 1E Pumping, Distribution & Storage

in pressure. A tank having adequate storage capacity when operated over 20 - 40 psi pressure range may be to smallwhen operated at 40 - 60 psi. Refer to Table 1-39 for pressure range vs. usable tank volume relationships.

Commercial pressure switches are commonly available with a pressure differential of 20 psi. Thus, if the minimumpressure needed is 40 psi, a maximum pressure of 60 psi is usually adopted. Typical low/high ratios are 20/40,30/50, 40/60, 50/75, and 50/80.

1-93

Table 1-39: Pressure Range vs. Usable Storage Volume

Pressure Range (psi) Avg. Design (psi) Usable Tank Vol. (%) Storage Correction Factor

20 - 40 30 15.5 .50

30 - 50 40 10.2 .70

40 - 60 50 7.2 1.00

50 - 75 60 6.2 1.15

50 - 80 65 7.1 1.00

Note: Usable (draw down) tank volumes are based on an initial atmospleric (atm.) charge of 14.7 psi. Usabletank volume is doubled for every 14.7 psi charge above the initial atm. charge.

As the minimum pressure increases, the pressure differential must increase for efficient use of the tank capacity. Thedesign objective is to draw off as much water from the tank as possible before the pressure is reduced to theminimum point in order to hold the number of times per hour (cycles per hour) the pump must start and stop.

Step 3. The pump should be selected with a capacity of at least 125% of the calculated peak demand against a totalhead equal to the average design pressure, plus the head required to get water to the tank from the deep well orother source. The 25% greater capacity provides a factor of safety against inaccurate consumption estimates and lossof pump capacity as a result of long term wear.

Step 4. The tank should be large enough to limit the number of pump cycles to 6 per hour (10 to 15 cycles per hourmay be acceptable in small domestic systems). Under simplified conditions, 6 cycles per hour allows the pump torun 5minutes and to be off 5 minutes. At an average demand, the number of cycles will reduce to a much smallerfigure. The maximum number of cycles occurs when demand is equal to 1/2 of the pump capacity. If the demand isgreater than this, the pump operates longer than five minutes (up to continuous operation when demand equalspump capacity) and at lesser demand the pump operates less frequently (down to zero cycles at zero demand).

Correct tank size depends on pressure differential and relative volume of air maintained in the tank. A commontechnique used to determine pressure tank size for general water supply applications, where the maximum numberof pump cycles should be limited to six (6) or less is described as follows:

The gross volume of the tank should be at least 10 times the capacity of the pump at the average tank pressure (ie. 250gpm pump capacity - 2500 gallon tank volume) at a base pressure range of 40 - 60 psi, corrected for usable storage.

This guide line provides approximately .75 gal./gpm of usable storage. A value of .5 gal./gpm is acceptable where10 to 15 cycles per hour is permissible. A conservative value of 1.0 gal/gpm should be used when the usage is notclearly defined.

Example 1-3: 100 gpm, 30 - 50 psi range

1) Est. tank size (40 - 60 psi)100 gpm x 10 gal./gpm = 1000 gal.

2) Tank volume (corr. for usable vol. @ 30 - 50 psi) 1000 gal (.70) = 700 gal, Table 1-39

Note: Tank sizes listed in Table 1-40 are based on the above referenced general selection guidelines


Sect

ion

1

Air Controls. When air and water in a pressure tank are in direct contact, water absorbs some of the air. If theabsorbed air is not replaced, the tank becomes “water logged” and causes the pump to rapid cycle any time a wateroutlet is opened. The typical air controls used for hydro-pneumatic systems are discussed as follows.

Constant - Air. These devices are designed as part of the pressure tank and range from a movable separator to anelastic air container. Tank utilizing the constant air process are commonly referred to as captive air or bladder tankswhich can be precharged to increase the usable storage capacity for given size tank. These types of tanks arelimited primarily to small domestic systems.

Add - Air. The air compressor and associated controls are the most common add-air method utilized in large hydro-pneumatic systems. The air/water volume relationship is maintained through the addition of air when the waterlevel within the tank rises above the ideal level based on the operating pressure range. Compressor system aregenerally acoustically enclosed for quite operation. In its simplest form, the add-air method involves the periodicdraining of the pressure tank to allow for the addition of a fresh air charge.

Air-Release. These devices are designed to release excess air that is forced into the tank by the pump. If the excessair is not released the tank will become “air bound”, affording little storage. The air venting valve must be placedon the tank at the proper height to maintain the correct air/water volume relationship for the operating pressurerange selected. The air release technique is commonly employed in both small and large systems.

Refer to Table 1-41 for air/liquid relationships for optimum tank efficiency (optimum air/water ratio) for commonpressure ranges.

Submersible Pump/Air Control Considerations. A submersible pump equipped with a built in /or inline checkvalve can be easily applied to any of the tank air volume control methods. When the constant or add-air method isemployed, no special modifications are needed. The air-release method will require the addition of a bleeder valveand snifter value (modified schrader valve) to drain a short internal of pipe and provide a point of entry for the aircharge respectively. Air is added to the tank at the start of each cycle.

When the submersible is not operated with a down hole check valve, the three air volume control methods are stillapplicable. It will be necessary to use an air release valve in the discharge line to exhaust all air in the column pipeahead of the tank when the constant or add-air controls are used. On deep settings, it may also be desirable toexhaust a majority of the excess air when utilizing air-release tank volume controls to reduce the noise associatedwith tank venting. It is also a good practice to set the minimum pressure switch setting 5 psi above the actualminimum pressure requirement in deep submersible setting where no down hole check valves are used. A backspin(time delay) timer should also be incorporated into the control scheme to eliminate possible start-up duringbackspin.

Air/Vacuum Release Valve Sizing. If an air/vacuum release valve is required, the rate of air that must be exchangedcan be determined from the formula:

where; Q = pump flow in gpm @ open dischargecfm = cubic feet per minute of exhaust air 7.48 = gal./cu. ft. conversion

The actual selection of the air/vacuum release valve is generally based on exhaust air requirements and maximumpressure differential of 2 psi. A pressure differential of .5 psi or less is recommended for quiet operation.


cfm = Q/7.48


Section 1


Figure 1-32: Typical Hydro-Pneumatic System

Drain

Union Gate

Outlet

LL HL

Slope

Union

Gate

Check Valve

*Air-ReleaseValve

Flex Coupling(to reduce noise)

Discharge CompanionFlange

Discharge Elbow

J-Box

Gauge Glass(optional)

Pressure Switch

*Air-Release,Air Venting System

**Add-Air, Compressor System

Pressure Relief Valve(valve rating to be less thantank working presure rating)

*Snifter Valve

*Bleeder Valve,place 4' below well seal

Pipe size to match discharge elbow on short runs

Note: 1. Consult water supply regulatory authority for specific system requirements.2. Tank may be mounted in any secure fashion. Provisions must be made to avoid scratching and noise, as

the tank expands and contracts.3. Set tank where it will not be subject to freezing temperature or extreme heat.4. Place pump as near a practical to well.

* Controls/appurtenances required for Air-Release tank air/water maintenance controls, when pumps equippedwith built-in or in-line check valve.

** Controls/appurtenances required for Add-Air tank air/water maintenance controls, when pumps equipped withbuilt-in or in-line check valve.


Sect

ion

1


Table 1-40: Minimum Recommended Pressure Tank Capacity – (Gal)

PUMP PRESSURE RANGE (psi)

(gpm) 20 - 40 30 - 50 40 - 60 50 - 75 50 - 80

10 50 (82) 70 (82) 100 (120) 115 (120) 100 (120)

15 75 (82) 105 (120) 150 (180) 173 (180) 150 (180)

20 100 (120) 140 (180) 200 (220) 230 (315) 200 (220)

30 150 (180) 210 (220) 300 (315) 345 (525) 300 (315)

40 200 (220) 280 (315) 400 (525) 460 (525) 400 (525)

50 250 (315) 350 (525) 500 (525) 575 (1000) 500 (525)

60 300 (315) 420 (525) 600 (1000) 690 (1000) 600 (1000)

70 350 (525) 490 (525) 700 (1000) 805 (1000) 700 (1000)

80 400 (525) 560 (1000) 800 (1000) 920 (1000) 800 (1000)

90 450 (525) 630 (1000) 900 (1000) 1035 900 (1000)

100 500 (525) 700 (1000) 1000 (1000) 1150 1000 (1000)

125 625 (1000) 875 (1000) 1250 1438 1250

150 750 (1000) 1050 1500 1725 1500

175 875 (1000) 1225 1750 2013 1750

200 1000 1400 2000 2300 2000

250 1250 1750 2500 2875 2500

300 1500 2100 3000 3450 3000

350 1750 2450 3500 4025 3500

400 2000 2800 4000 4600 4000

500 2500 3500 5000 5750 5000

600 2800 4200 6000 6900 6000

700 3000 4900 7000 8050 7000

800 3500 5600 8000 9200 8000

900 4000 3600 9000 10,350 9000

1000 5000 7000 10,000 11,500 10,000

1100 5500 7700 11,000 12,650 11,000

1200 6000 8400 12,000 13,800 12,000

Note: 1. The above referenced steel tank sizes are minimums, based on the general rule of thumb for calculatinggross volume of 10 gal./gpm at a base pressure range of 40-60 psi (corrected for usable/drawdownstorage).

2. Bracketed ( ) figures represent readily available trade size steel hydro-pneumatic tanks. Always select atank equal to or larger than the minimum volume specified above.

3. Steel pressure tanks available in sizes ranging from 18 gal. to 30,000 gal. Bladder/captive air tanks aretypically used when flow rates are 50 gpm or less.


Section 1


Table 1-41: Relationship Between Air & Liquid

Vertical TankHeight

HL

LL

Horizontal TankDiameter

HL LL

Legend:HL = High tank water level @ cut-out pressure for optimum A/W ratioLL = Low tank water level @ cut-in pressure for optimum A/W ratioA/W = Air/Water ratio for specified pressure range w/o external air charge

Horizontal (% Diameter) Vertical (% Height)

Cut-in (LL) Cut-out (HL) Cut-in (LL) Cut-out (HL) LL HL

20 - 40 1.58 55 67 57 74 57.7 73.2 15.5

30 - 50 1.44 63 71 67 77 67.2 77.4 10.2

40 - 60 1.37 67 75 74 80 73.2 80.4 7.2

50 - 75 1.38 71 77 77 83 77.4 83.6 6.2

50 - 80 1.47 71 78 77 85 77.4 84.5 7.1

PressureRange(psi)

Cut-out/Cut-in

PressureRatio

Water Level (WL) for optimum tank efficiency(optimum A/W ratio) for the specified pressure

Tank Volume

(%)

Usable/Drawdown

Volume(%)

Note: 1. Air-Release (air vent valve) tank air volume controls should be installed at the LOW LEVEL (LL) heightas indicated for the specified pressure range.

2. Add-Air (compressor WL maintenance probe) should be placed at the HIGH LEVEL (HL) height asindicated for the specified pressure range


Sect

ion

1


Table 1-42: Typical Captive Air or Bladder Tank Sizing (pre-charged/supercharged pressure tanks)

Water

Bladderor

Diaphram

Air FillValve

20/40 30/50 40/60

1 WX-101 8 12 5/8 2.0 .7 .6 .5 3/4 NPTM 5 20

2.5 WX-102 11 15 4.4 1.6 1.4 1.2 3/4 NPTM 9 20

5 WX-103 11 24 3/4 8.6 3.1 2.7 2.2 3/4 NPTM 15 30

6 WX-104 15 3/8 17 3/8 10.3 3.8 3.2 2.8 1 NPTF 20 30

6 WX-104S 15 3/8 19 1/4 10.3 3.8 3.2 2.8 1 NPTF 25 30

7.5 WX-200 15 3/8 22 14.0 5.2 4.3 3.8 1 NPTF 25 30

7.5 WX-201 15 3/8 23 7/8 14.0 5.1 4.3 3.7 1 NPTF 27 30

10 WX-202 15 3/8 31 5/8 20.0 7.3 6.2 5.4 1 NPTF 35 30

15 WX-203 15 3/8 46 3/4 32.0 - 9.9 8.6 1 NPTF 43 30

18 WX-205 22 29 1/2 34.0 12.4 10.5 9.1 1 1/4 NPTF 61 38

20 WX-250 22 35 5/8 44.0 16.3 13.6 11.9 1 1/4 NPTF 69 38

30 WX-251 22 46 3/4 62.0 22.9 19.2 16.7 1 1/4 NPTF 92 38

45 WX-302 26 47 3/16 86.0 31.8 26.7 23.2 1 1/4 NPTF 123 38

60 WX-350 26 61 7/8 119.0 44.0 36.9 32.1 1 1/4 NPTF 166 38

Note: 1: Drawdown can be affected by various ambient and system conditions. Including temperature andpressure.

2. Data reprinted with permission of Amtrol, Inc. (WXT-SCRD91)3. Pump flow rate (gpm) based on approximately 5 gal. useful (drawdown) storage for every 10 gpm @

40/60 psi pressure switch setting. Information provided to give a relative tank input/output capacity.4. For every 14.7 psi air charge above the initial atmospheric charge, the usable capacity of a standard tank

will be doubled.

Pump(gpm)

Dimensions

Diameter Height(in.) (in.)

TotalVolume(gal.)

Drawdown/Usable Vol. (gal.)@ various cut-in/out pres. (psi)

Typ. Sys.Connection

(in.)

AmtrolModel

No.

Typ.Ship Wt.

(lbs.)

TankPrecharge

(psig)


Section 2

Section 2A Pump Fundamentals



SECTION 2: PUMP HYDRAULICS & APPLICATION CONSIDERATION

2A PUMP FUNDAMENTALS

• Types & Classifications of Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2• Centrifugal Pump - Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3• Submersible Definitions & General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3• Submersible Pump Performance Characteristics and Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5• Submersible Pumping System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9• Submersible - Sizing & Installation Dimensional Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13

2B HYDRAULIC FUNDAMENTALS

• Density, Specific Gravity and Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15• Pressure and Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15• Fluid Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17• Vapor Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17• NPSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18• Power, Efficiency and Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21• Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22

2C HYDRAULIC RELATIONSHIPS

• Affinity Laws - Pump Speeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-24• Specific Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-25• Speed Torque Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-26• System Head Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-28• Parallel and Series Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-31• Minimum Flow - Temperature Rise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-34• Axial Thrust - Maximum Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-36

2D PUMPING SYSTEM APPLICATION CONSIDERATIONS

• Cavitation, Vortexing and Submergence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-38• Entrained Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-40• Entrained Solids (Sandy Water) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-42• Water Hammer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-43• Downhole Check Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-45• Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-46• Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-52• Power Consumption and Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-56

2E ENGINEERING PROPERTIES OF WATER:

• Table 2-15: Altitude vs. Barometric Pressure and Boiling Point of Water . . . . . . . . . . . . . . . . . . . . . . . 2-60• Table 2-16: Elevations for Various Municipalities (U.S. & Canada) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-60• Table 2-17: Vacuum to Suction Lift Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-61• Table 2-18: Properties of Water from 32°F to 300°F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-62• Figure 2-32: Suction Lift Correction for Elevation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-63• Figure 2-33: Suction Lift Correction for Water Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-63

2-1


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2

Water Well Pumps. Pumps used for water well service are sometimes classified as shallow or deep well types. Apump installed above the well, which takes in water by suction lift is called a shallow well pump (lift generally<25’). Typical shallow well pumps are jet pumps and single stage centrifugals with foot valve. A pump installed inthe well, with the pump inlet initially submerged below the pumping level is called a deep well pump (positivesubmergence pump). Typical Deep well pump types are vertical turbines and submersibles.

Deep Well Pumps. Deep wells are generally pumped by multistage diffuser centrifugal pumps commonly calledvertical turbines. These pumps develop high head by using a series of small impellers rather than a single large one.Line shaft vertical turbine pumps may be either oil or water lubricated. Water lubricated pumps are sometimescalled open line shaft pumps since the drive shaft is exposed to the flow (Figure 2-2, A). Deep well pumps may bedriven either by a motor at the top connected to the pump by a line shaft, or by a submerged motor (submersible)below the pump (Figure 2-2, B).

Section 2A Pump Fundamentals2-2

Figure 2-2: Deep Well Pump Type

Diagram A – Vertical Turbine Pump Diagram B – Submersible Well Pump

Figure 2-1: Pump Type Overview

Shallow Well

Horiz. Booster

Dry Pit

Deep Well

Vert. Booster

Canned

Wet Pit

Sump

Jet

Volute/Centrifugal

Split Case

Turbine/Submersible

Propeller

Radial Flow

Mixed Flow

Axial Flow

Reciprocating

Rotary

Dynamic/Centrifugal(Variable Torque)

Positive Displacement(Constant Torque)

Pumps

2A PUMP FUNDAMENTALSTypes & Classifications of PumpsPumping equipment can be broadly divided into two general categories, positive displacement and dynamic types(centrifugal). Centrifugal pumps are further typed by their general mechanical configuration or by impeller type (ie.axial flow, mixed or radial flow). The most common centrifugal pump types by mechanical configuration are;turbine, propeller and volute (centrifugal). The multi-stage submersible is a turbine pump sub-group. Theclassification relationships are illustrated below in Figure 2-1.


Section 2


Centrifugal Type - Submersible Pumps. In a centrifugal pump, pumping action is generated by means ofcentrifugal force. A submersible pump is a multi-staged centrifugal pump. The essential components of asubmersible pump are the intake, impellers, pump/bowl shaft, diffuser and discharge; all driven by a electric motorprime mover. Each rotating impeller and stationary diffuser element is commonly referred to as a stage orintermediate. A simplified submersible diagram is illustrated in Figure 2-3 below:

Centrifugal Pump - Theory of Operation As the impeller rotates, liquid istaken in at the eye of theimpeller and forced out alongvanes to its tips. The liquidmoves faster at the tips of theimpeller than at the eye. Thefluid is then gathered in thediffusing section, where velocityenergy is converted to pressureenergy in progressive stages untildischarge. The rapid outwardmovement of fluid from the eyeof the impellers creates a lowpressure region within eye,which pulls more fluid into theintake at the same rate asdischarged. Pressure and flowperformance of a submersiblepump is a function of impellerdiameter, speed, number ofstages, width of internalimpeller/diffuser water passagesand vane configuration.

Impellers are generally classifiedas open, semi-open or enclosed.Enclosed impellers can be of thefloating or fixed type based onthe industry or applicationrequirements. Groundwatersubmersible pumps, 6” andlarger, are typically of theenclosed fixed typeconfiguration. The information

presented in this manual is specifically applicable to the enclosed - fixed type impeller configuration.

Submersible Pump Definitions and General InformationA submersible pump can be broadly described as a pumping unit in which the pump and its driving motor operatesubmerged in the liquid being pumped. This broad definition applies to many pump types; however, the focus ofthis manual is on the deep well submersible pump with enclosed - fixed type impellers.

A deep well submersible pump consists of a multistage centrifugal pump directly coupled to an electric-motorwhich is designed to operate completely submerged in cool water. Generally the pressure or pumping depthcapabilities vary with the number of impellers used and the capacity varies with the impeller design. Mostsubmersibles utilize a 2 pole - 3600 rpm (ideal speed) motor designed to fit typical water well diameters (4” - 20”).Domestic sizes range from 1/4 to 2 Hp and commercial sizes are available to 250 Hp and larger, for specialapplications. The advantages are low cost per gallon of water pumped, ability to be installed at great depths, quietoperation, ease of installation and low over all installation cost especially for deeper settings. Priming is automatic

2-3

Figure 2-3: Submersible Pump Elementary Overview Diagram

Motor Shaft

Discharge

Motor

Water Intake

ImpellerStages


Sect

ion

2

and maintenance is no problem. The primary disadvantage of a submersible pumping unit, assuming good designpractices are followed, is the necessity to pull the entire pump regardless of problem (electrical or mechanical).

Figure 2-4 illustrates a typical form of construction and associated terminology used in the manufacture ofsubmersible pump-motor units. This assembly shown is of the threaded bowl/intermediate construction, employedby Grundfos, although bolted construction is used by many pump manufacturers.


Figure 2-4: Typical Multistage Submersible Pump Construction Sectional Drawing

17

71

19

69

70

39

1

3

2

4

6

16

8

11

72

6b

8a

11c

12

7

14

24

13

10

Pos. Description

1 Valve casing

2 Valve cup

3 Valve seat

4 Top intermediate chamber

6 Top bearing

6b Lower bearing

7 Neck ring

8 Intermediate bearing

8a Spacing washer for stop ring

10 Bottom intermediate chamber with stop ring

11 Nut for split cone

11c Nut for stop ring

12 Split cone

13 Impeller

14 Suction interconnector

16 Shaft

17 Strap

19 Nut for strap

24 Coupling

39 Spring for valve cup

69 Ring for strap

70 Valve guide complete

71 Washer

72 Wear ring

Pump connection to motors of different sizes is typically accomplished through the bolting of the inlet adapter(suction interconnector) to the motor bracket. Shafts are typically stainless steel or other corrosion-resistant material.Intermediate stages (bowls), impellers and other fabricated/cast components may be of cast iron, bronze, moldedthermoplastic, stainless steel or special alloy, depending on the operating environment and pump application.Impellers may be mounted to the bowl/pump shaft through the use of a key, formed shaft, (spline shaft), split coneor lock collet. Rubber and/or bronze bearings are typically used in water supply applications. Most manufacturersoffer a variety of designs, features and material options. Specific product information is normally provided by themanufacture in catalog format.


Section 2


Submersible Pump Performance Characteristics and CurvesGeneral. Centrifugal pumps have head-flow characteristics, just as motors have speed-torque characteristics. At afixed speed, the head developed by a pump will decrease as the flow is increased. Different pump designs willproduce different characteristics, as illustrated in Figure 2-5 below:

Reading a pump curve isfairly straightforward.Pump/performancecurves consist of asimple graph with flowrates (Q) along thehorizontal axis andpressures/head (H)along the vertical axis.The data graphed on thecurve is typically basedon a fixed speed.

PerformanceCharacteristics.Performancecharacteristics ofcentrifugal/turbine type -submersible pumps aredescribed in curvesdeveloped by pump

manufacturers. Typical performance curve presentations are illustrated in Figure 2-7 and describes the relationshipsbetween (1) capacity and total dynamic head, (2) capacity and efficiency, (3) capacity and brake horsepower, andin some cases, (4) capacity and net positive suction head (NPSH). Individual curve parameters are discussed below.

Performance Curves1. Total dynamic head- capacity (H-Q) curves show the total head developed by the pump at a given capacity.

Figure 2-6 shows that a pump will operate over conditions ranging from shutoff (no flow) to maximum flow.Maximum total head usually occurs at shutoff. As capacity increases, total head developed decreases. Maximumflow will occur with minimum head.

The characteristic curves for a multi-stage turbine type submersible pump depend upon the number of stages orimpellers. Each impeller normally will have the same characteristic curve as the next, the composite curve isobtained by adding the head per stage at a given discharge (flow rate) to determine the effect of seriesinstallation.

The H-Q performance curves for engineered submersible pumps are typically show the head developed by onestage. If a multistage pump is used, the total head developed at a particular capacity, (based on a single stageperformance curve) can be calculated using the formula:

where; H = total head of pump, n = number of stages, Hs = head per stage.

2. Efficiency-capacity (PE - Q) curves describe the relationship between pump efficiency and capacity. Efficiency ismaximized at the design capacity where hydraulic, mechanical, and leakage losses within a pump are minimum.These losses included leakage between impeller and intermediates; fluid friction losses in all flow passages suchas diffuser vanes, impeller, intermediates and thrust bearing friction. If the pump operates at capacities greater orless than at the design capacity, pump efficiency will decrease. The efficiency may change as more stages areadded. Efficiency corrections for multistage pumps are provided with the manufacturers performance curve.

3. Brake horsepower-capacity (BHp-Q) curves show the brake horsepower required by the pump at a givencapacity within its performance range. They can be used to select and properly size a motor, as well as quantifythe impeller loading characteristic as nonoverloading or overloading. In the nonoverloading case, BHp varies

2-5

Figure 2-5: Pump Characteristic Illustration

Pump B

FLOW

HE

AD

Pump A

H = n x Hs

slightly over the pump’soperating range with themaximum BHpoccurring at or near thepoint of maximumefficiency. A change inoperating conditions willnot overload the motorif the motor is sized formaximum efficiencyconditions. Overloadingcurves are characterizedby large changes in BHpover a pump’s operatingrange such that a motorselected for one set ofoperating conditionsmay become overloadedif changes in theseconditions occur. Pumps

with overloading performance curves are rarely used in submersible water supply applications.

The type of BHp-Q curve depends primarily on the impeller design; (1) Radial flow impellers usually haveoverloading curves where BHp increases as capacity increases (2) Axial-flow impellers also have overloadingcurves; however, BHp increases as capacity decreases and maximum BHp occurs at shut off (3) Mixed-lowimpellers generally have non-overloading curves.

The total BHp requirement for a multistage pump, (based on a single stage performance curve) can be calculatedusing the formula:

where; BHp = required BHp for multistage pump, n = number of stages, BHp/stg. = Hp required by one stages.

4. Net Positive Suction Head - Capacity (NPSH-Q) curves show the required NPSH (NPSHR) for a particular pumpdesign to operate without cavitation. Pump NPSH requirements increases as capacity increases. Pump NPSHrequirements are determined by the manufacturer. The topic of NPSH is discussed in detail in Section 2B.

In addition to the minimum parameters described above, submergence minimums and hydraulic thrust data areoften presented on the performance curve for engineered products. Many manufacturers feature a single stagecurve with head and capacity (H-Q) shown for full-sized impeller and for one or more trimmed (reduceddiameter) impellers. Other manufacturers present a cluster of curves where capacity and head are shown foreach stage up to the maximum permissible number of stages. The closed impeller design (upper and lowershroud) is most commonly used in submersible applications. Semi-open and axial flow impellers can not beeffectively used in submersible applications as axial (lateral) clearance adjustments for optimum performance aredifficult to maintain.


Sect

ion

2


Figure 2-6: Elementary H-Q of Performance - Multistage Turbine Type

FLOW

HE

AD

3 stage

2 stage

1 stage

BHp = n x BHp/stg.


Section 2

Section 2A Pump Fundamentals 2-7

Figure 2-7: Typical 8" Submersible - 3600 rpm Multi-Stage Performance Curve

1400

1300

1200

1100

1000

900

800

700

600

500

400

300

200

100

00 50 100 150 200 250 300 350 400 450 500

CAPACITY (GPM)

HE

AD

(F

EE

T)

80

70

60

50

EF

FIC

IEN

CY

(%

)

385S1000-13 (100 HP)

385S1000-12 (100 HP)

385S1000-11 (100 HP)

385S750-10 (75 HP)

385S750-9 (75 HP)

385S750-8 (75 HP)

385S600-7 (60 HP) *

385S500-6 (60 HP) *

385S400-5 (40 HP) *

385S400-4 (40 HP) *

385S250-3 (25 HP)

385S200-2 (20 HP)

385S100-1 (10 HP) *

EFF. (%)

34503525RPM

OPERATING RANGE: 260 TO 550 GPMCAPACITIES BELOW 300 GPMSEE MODEL 300S


Sect

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2

Note: When a pump is connected to a system, the system pressure will dictate the natural operating point for thepump.

Performance - Speed Relationships. Many manufactures who build both submersible and turbine pumps will provideH-Q performance based on the speed of the surface motor driver. Submersible motors have slightly lower full loadspeeds compared to comparable surface motors as a result of their compact design. Typical 2-pole speeds forsurface and submersible motors range from 3570 - 3500 rpm and 3540 - 3450 rpm respectively. The resulting H-Qdifferences can be neglected in most applications. Should a more precise H-Q representation be required, theperformance curve can be derated using the affinity laws.

Note: Speed difference also exists between submersible motor designs and sizes. Always verify the pumpperformance curve basis of calculation with the actual full load speed of the motor to be used.

Shape of Pump Curve. There are three types of H-Q curves steep, flat and drooping. Steep curves are characterizedby a large change in total head between shut off and capacity at maximum efficiency, while a small change occursfor flat curves. Drooping curves are characterized by an increase in total head to some maximum value as capacity

increases, then adecrease as capacitycontinues to increase;maximum head does notoccur at shutoff.

Steep and flat curves arecalled stable curvesbecause only onecapacity exists for aparticular head.Drooping curves arecalled unstable curves,as two operatingcapacities for given headare possible on eitherside of the maximumhead point. Theinstability created by theexistence of two


Figure 2-8: Typical 8" Submersible - 3600 rpm Single-Stage Performance Curve

0 50 100 150 200 250 300 350 400 450 500 550

30

25

20

15

10

5

0

30

25

20

15

10

CAPACITY (GPM)

HE

AD

(F

EE

T)

NP

SH

(F

EE

T)

0 50 100 150 200 250 300 350 400 450 500 550

100

90

80

70

60

50

40

30

20

10

0

80

70

60

50

40

10

8

6

CAPACITY (GPM)

HE

AD

(F

EE

T)

EF

FIC

IEN

CY

(%

)H

P

Figure 2-9: Pump Characteristic Curve Shapes

Flat rising

DISCHARGE

HE

AD

Steep rising

Steep drooping

385 GPM, Single Stage Curves, 60 Hz

possible discharge rates at the same head can cause a system to “hunt” back and forth between capacities.Performance curves also may have irregularities or flat regions which can cause unstable performance if the pumpoperates within the unstable region.

Radial-flow (low specific speed) impellers generally have flat H-Q characteristic curves, while axial-flow (highspecific speed) impellers have steep curves. Mixed-flow impellers have intermediate characteristics. In most watersupply applications pumps with moderately steep characteristics are preferable.

Hydraulic Characteristic and Curve Standards. The head (in feet of liquid) developed by a centrifugal pump isindependent of the specific gravity, water at normal temperatures (60 - 70°F) with a specific gravity of 1.00 is theliquid almost universally used in establishing centrifugal pump performance characteristics. If the head for a specificapplication is determined in feet, then the desired head and capacity can be read without correction as long as theviscosity of the liquid is similar to that of water. The horsepower (BHp) curve, which is also based on a specificgravity of 1.0, can be used for fluids other than water (if viscosity is similar to water) by multiplying the horsepowerfor water by the specific gravity of the liquid being handled.

The hydraulic characteristics of centrifugal pumps usually permit considerable latitude in the range of operatingconditions. Ideally, the design point and operation point should be maintained close to the best efficiency point(BEP); however, substantial variations in flow either to the right (increasing) or to the left (decreasing) of the BEPare usually permissible, operating back on the curve at reduced flow, or at excessive run out may result in radialthrust, or cavitation causing damage.

For pumps in the centrifugal range of specific speeds (radial flow impellers) the relationships between capacity,head and horsepower with changes in impeller diameter and speed can be predicted using the affinity laws. Theaffinity law topic is discussed in detail in Section 2C.

Submersible Pumping System OverviewApplication. The submersible pump is especially suited to deepwell and booster service for industrial, commercial,agricultural and municipal water systems. The pump utilizes a submersible induction motor coupled directly to thepump end (bowl assembly) and is designed to operate completely submerged in the fluid being pumped. Power issupplied to the motor through waterproof electrical cable. In deepwell applications the pump, motor and cable aresuspended in the well by the column (riser) pipe. Booster applications involve installing the unit vertically in abarrel (can) or sump, or horizontally in a pipe line or tank. Since the entire unit is either enclosed or below thesurface of the ground, there are several applications where the submersible pump has many advantages whencompared to line shaft vertical turbines. These advantages and application are:

• Deep settings and high head • Crooked wells • Quiet and vandal resistant • Low initial equipment and installation costs• Vertical or horizontal application • Unaffected by weather extremes• No routine maintenance required • Minimum space requirement• Small diameter - high flows

High temperature (100°F +) and abrasive environments are generally not conducive to submersible applications. Insuch cases, the line shaft vertical turbines are usually more suitable.

Typical Operation. Submersible pumps may be operated and controlled in the same manner as any other types ofturbine pumps in similar applications. No special consideration peculiar to the submersible is generally necessary,with the exception of the motor starting equipment. The motor, being installed in the pumped fluid, may not besubjected to the same ambient temperature as the overload relays in the starter.

Submersible Pumping System Component Overview. Submersible pumping system equipment requirementscan be broken down into two component categories, sub-surface and surface. A typical submersible pumpingsystem is shown in Figure 2-10.


Section 2

Section 2A Pump Fundamentals 2-9


Sect

ion

2

The major sub-surface components are:• Submersible Motor • Pump End (Bowl Assembly)• Power Cable • Check Valve• Column (Riser/Drop) Pipe

The major surface components are:• Starter Panel (Controller) • Surface Discharge• Surface Discharge Piping • Transformers

A brief description of the major functional components, as well as general selection and application criteria guidelines are presented as follows:

Submersible Motor. The electric motors most commonly used in submersible pump water supply applications aretwo pole (3600 rpm), 3 - phase, squirrel cage, induction type - operated at 60 Hz. Motor construction is typically ofthe hermetically sealed - canned type, in which the winding is insolated from the motor liquid (de-ionized water).Motor liquid is required to dissipate heat and for thrust bearing lubrication. The motor is attached to the pump endassembly via a coupling and bolted interconnector, which creates integrated submersible unit. The motor thrustbearing carries the entire thrust load of the pump. See Section 4A for a detailed discussion of submersible motors.

Submersible motors rely on fluid movement over the external housing to remove heat. The primary factors whichcontribute to early motor failure are; insufficient or lack of cooling flow, prolong low voltage operation and highambient fluid temperature. Mitigation of adverse motor operating conditions are discussed in Section 4B under thegeneral heading of motor cooling.

Pump End. The pump end (bowl assembly) consists of single or multiple stages to meet exact system requirements.A wide range of pump end sizes are available to meet system capacity requirements. Grundfos standardconstruction utilizes all stainless steel construction and industrial grade rubber (NBR) seals and bearings. Stainlesssteel standard construction allows for a greater range of application when compared to cast iron - bronze fit (CIBF)standard construction. See Section 5 for a detailed presentation of Grundfos submersible pumping products.

Submersible pumps are relatively trouble free under most operating condition. When problems do arise, they canusually be attributed to inadequate suction/intake condition or the presence of sand (abrasives) in the water.Mitigation of adverse pumping conditions are discussed in greater through out this section.

Power Cable. Power cable is used to transmit power from the starter (controller) to the motor and is selectedaccording to load, voltage and length required. One extra foot for each fifty feet of length should be allowed, plusan additional ten to fifty feet for surface connections. Electrical losses in the cable contribute to reduced overallplant efficiency, and for this reason it may be advantageous to oversize cable on some installation (year roundoperation - deep setting). Cable is typically supported on column pipe by means of cable clamps and stainless steelbands, nylon ties or tape.

Check Valves. Column check valves are recommended for pump settings in excess of 450 feet. For pump settings inexcess of 750 feet two check valves are recommended. The bottom check valve should be located 40 to 60 feetabove the pump, if the pump is not equipped with a built-in check valve.

In no case should the distance between check valves and the surface discharge plate be equal. Unequal distancesare essential to prevent harmonic valve hammer. It is recommended that column check valve(s) be utilized on anyinstallation where there is danger of pump start during back spin or danger of well damage as a result of surgingcreated by rapid column drainage. In cases where it is desirable to drain the column pipe - a slow leak check valveshould be used in conjunction with a backspin timer.

Care must be used when installing a check valve on the surface or within the well above the static water level. Aimplosive vacuum can form if water recedes rapidly down the column pipe or destructive water hammer can occuras the void created by the vacuum is filled. A vacuum/air relief valve should be considered for installation in thedischarge header or a snifter (air inlet) valve located in the upper most column joint as a fail safe should a downhole check valve fail. The air relief/inlet valve should be placed on the downstream side of a surface check valve oron the upstream side of a column pipe check valve to prevent vacuum formation.



Section 2


Brass plug drain valves are available for small diameter column pipe. Drain valves are sometimes use to prevent thepulling of a wet/heavy piping string. Drain valves are typically installed one joint above the check valve.

Column Pipe. Discharge pipe is usually provided in random length (16”-22’) with thread and coupled (T&C) endconnections. Ten or twenty foot lengths are typically specified. Tapered pipe thread (NPT) are normally used tofacilitate installations and resist motor torque. Starting torque will tend to loosen right hand threads if not adequatelymade up. When using straight thread pipe, all joints must be locked. Pipe should be sized to maintain a minimumvelocity of 5 feet per second. The column pipe length should be sufficient to keep complete submersible unit(pump and motor) submerged at all times.

Starter/Controller. Fixed speed-submersible motor starting equipment is sized and designed to deal with quick heatbuild-up commonly associated with the compact submersible motor designs. Conventional starters and pumpingplant panels with 3 leg protection may be used. Properly sized quick trip ambient compensated overload protectionis necessary for proper protection and is normally required to satisfy the motor manufactures warranty requirements.Overload relays should be of the current sensing type rather than thermally activated. In addition to overloadprotection; voltage parameter (high/low/balance) should be monitored. Each phase should be equipped with itsown lightning arrestor. Installations subject to rapid cycling should be equipped with a time delay relay.

Surface Discharge. The surface discharge is referred to in several different ways, common references are; dischargehead, discharge elbow, well seal, surface plate, etc. The function of the surface discharge is to carry the suspendedweight of the complete pumping unit and associated sub-surface components when full of water, and normallyincorporates an elbow or fitting for connection to surface discharge piping. Some form of surface discharges isrequired for well or booster application, with the exception of pitless adapter installation. The surface dischargeshould accommodate specific system needs such as a; junction box, lifting eyes, air vent/inspection port, cable seal,discharge connection, etc.

The surface discharge assembly must physically comply and be installed in accordance with applicable State orFederal sanitary requirements. Typical submersible pump discharge configurations are shown in Figure 2-10.

Surface Discharge Piping. Surface discharge piping should be designed and configured to provide for the functionalneeds of the system. Piping typically is of the same diameter as the column pipe. Valving should be configured toprovide isolation between the pump and the system to facilitate service. Other surface discharge appurtenancessuch as a; check valve, flow meter, air/vacuum larger. Layout should allow for a system bypass for pumping towaste and a reasonable test section for relief valve, flex coupling, control valve, etc. - should be provided based onspecific application requirements.

Transformers. The most common function of power distribution transformers serving a pumping plant, is to reducevoltage from distribution to utilization levels (ie. 4160 to 460V). In most water supply applications, transformers areprovided by the servicing utility, along with power metering equipment. Transformers are rated on the basis of KVAand must be size to handle the total connected load which is often greater than the pump alone. A full three phasetransformed bank is recommended for three phase motor application. The open delta configuration should beavoided when possible.

2-11


Sect

ion

2


Figure 2-10: Submersible Pumping System Component Overview

MotorController

Utility Supply

Well

Motor

Strainer

Pump End

Check Valve

Cable Clamp

Cable Splice

Power Cable Snifter Valve(Air Inlet - As Req)

System Bypass Valve

System Isolation Valve

Check Valve

Surface Plate(Well Seal)

Flex CouplingDischarge Elbow

Cable Seal/J-Box


Section 2


Submersible Pumping System - Sizing and Installation Dimensional RelationshipsFigure 2-11 illustrates the typical dimensional reference data required to size a deep well submersible pump. Thevarious hydraulic, water level and installation dimensional parameters are defined as follows:

2-13

Figure 2-11: Schematic of Key Submersible Pump System Dimensional Sizing Parameters

TSD

TH or H

SDCL

PWL

Hs

DD

AGH

Hf

SWL

Q

Discharge piping

Static Pressure System

HvNote: TDH = H + Hv Pump and motor assembly

Ground Level at Well - Datum

SWL = Static water level is the distance in feet/meters measured from the surface datum (ground level as illustrated)to the natural water level when the pump is not operating. The standing water level after pumping has beenstopped for five minutes (ie. well has recovered for 5 minutes) is often used as the SWL for pumping calculations.

DD = Drawdown is the stabilized distance in feet/meters to which the water level drops below the static water levelwhile the pump is operating. Drawdown varies with well yield and pump capacity - (DD = PWL - SWL).

PWL = Pumping water level is the distance in feet/meters measured from the surface datum (ground level asillustrated) to the stabilized level of the water with the pump operating at a predetermined capacity - (PWL = SWL +DD).

CL = Column / riser pipe vertical length in feet/meters typically measured from the well seal/discharge elbowmating flange (ground level as illustrated) to the discharge connection of the pump.

SD = Pump setting depth is the vertical distance in feet/meters, typically measured from the well seal/ dischargeelbow mating flange (ground level as illustrated) to the pump inlet.

TSD = Total vertical setting depth is the vertical distance in feet/meters, typically measured form the wellseal/discharge elbow mating flange (ground level as illustrated) to the most distant vertical point of the pump string.The most distant point is generally the bottom of the motor housing.

Hs = Submergence is the distance in feet/meters from the pumping water level to the pump inlet.


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2

AGH = Static discharge head (pressure) or above ground head is the vertical elevation in feet/meters from thesurface datum reference (ground level as illustrated) to provide the service pressure required to meet the point ofuse needs. Pressure may be converted to feet by multiplying by 2.31.

Hf = Friction head loss is the hydraulic energy loss in feet/meter of liquid needed to overcome the resistance toflow in pipe and fittings. Hf always includes sub-surface friction losses and can include surface discharge lossesdepending on the application.

H or TH = Total discharge head is the sum of the total hydraulic head requirements for the pump in feet/meter andconsists of the above ground static discharge head (AGH), pumping water level (PWL) and friction head (Hf)- (H =TH = AGH + PWL + Hf).

Hv = Velocity head expressed by the formula V2/2g can be defined as the equivalent head, measured in feet ormeters, of a stream of liquid with velocity “V”, if the kinetic energy involved were completely converted to head.Hv losses are a factor in calculating the total dynamic head (TDH), their value is relatively small and in most casescan be neglected when velocity is less than 10 fps (ie. Hv = .10 @ 10 fps). Hv losses are normally ignored incalculation of total dynamic head (TDH) in most applications; however, they are often included in compilingmanufacture test data.

TDH = Total dynamic head (not shown in schematic) is the differential head developed across the pump whichequals the algebraic sum of above ground discharge head (AGH), pumping water level (PWL), friction head (Hf),and velocity head at the discharge pipe (Hv) - (PWL = AGH + PWL + Hf + Hv). When sizing pumps for watersupply applications TDH = H = TH.

Additional Application Factors. The most crucial application parameters to be established for the proper selectionand sizing of pumping equipment are capacity (Q), total head (H) and Power-Horsepower (Hp) requirements.Additional factors to be considered when selecting a submersible pump and motor are:

1. Maximum number of stages: Pump manufacturers limit the total number of stages in a pump assembly. Whenusing a single stage curve, check the manufacturer’s data to ensure that the maximum number of stages is notexceeded in seeking a certain head and capacity.

2. Downthrust: The thrust bearing of a submersible motor is designed to carry the weight of the rotating elementsof the pump and motor assembly, as well as the hydraulic thrust created by the pump while it is operating. Eachmanufacture has a specific method for determination of hydraulic thrust loads. The maximum hydraulic thrustplus the pump rotating element weight should not exceed the thrust capacity of the motor. See Section 4A forexpansion of this application issue.

3. Upthrust: Upthrust may occur when pumps are operated at flow rates greater than those suggested by themanufacturer. If the pump is to be operated under these conditions, consult the pump or motor manufacturer forrecommendations. See Section 2C for expansion of this application issue.

4. Net Positive Suction Head (NPSH): NPSH combines the factors affecting the suction pressure at the inlet of thepump. They include pump intake losses, static suction lift (normally not encountered in submersibleapplications), vapor pressure, friction losses, and atmospheric conditions. See Section 2B for expansion of thisapplication issue.

5. Submergence: Submergence is the distance between the liquid level and intake setting. In order to insure properhydraulic performance, the pump manufactures minimum submergence requirements should be followed.Submergence is necessary to maintain prime, prevent vortexing and may be required to provide the pumpsNPSH requirement. See Section 2D for expansion of this application issue.



Section 2

Section 2B Hydraulic Fundamentals

2B HYDRAULIC FUNDAMENTALSThis section is not an attempt to present a course in Hydraulics, but rather a review of the terms, formulae, andapplications commonly encountered in the water supply industry involving submersible pumps. The science ofhydraulics is the study of the behavior of liquids at rest and in motion. We are interested in the information anddata necessary to aid in the solution of problems involving the flow of liquids commonly pumped by electricallydriven centrifugal pumps.

The fluid of primary interest is cool water in the temperature range of 50 -85°F, other selective fluids, which can behandled with centrifical pumps, are mentioned for completeness. In most water supply pumping applications,variations in water viscosity and density associated with temperature variations can be neglected, as a result of thenarrow fluid temperature operating range commonly encountered.

In order to move (pump) water against gravity or to force it into a pressure vessel, and/or to simply overcome pipefriction and associated losses, work must be expended. The various hydraulic and special pumping applicationrelative to this objective are discussed throughout this section.

Density, Specific Gravity and Specific WeightDensity. The density of a liquid is its weight per unit volume. Fresh water has a density of 62.4 pounds per cubicfoot (lbs./cu. ft.) or 8.34 pounds per gallon (lbs./gal.). A liquid has many different numerical terms to describe itsdensity but only one specific gravity (sg). In solving any pumping problem, it is advisable to convert density to sg.

Specific Gravity. Specific gravity (sg) is a relative measure of fluid’s density as compared with water at a standardtemperature (most often 60°F). The sg of water at 60°F is 1.0. If the density of the fluid is greater than water, itsspecific gravity will be greater than 1. A sg of 1.2 means its density is 20% greater than water. The sg of liquid doesnot affect the performance of a pump except for the horsepower which is required.

Specific gravity is sometimes expressed in terms relative to a specific industry. Two of the most common alternativemethods for expressing sg are degrees API (sg usually < 1.0) and Baume degrees (sg usually > 1.0). Both scales canbe related to the sg of water by the following formulas:

Refer to Table 2-18 for a listing of sg for water over a temperature range of 32 -300°F.

Specific Weight. The specific weight of a fluid can be determined by multiplying the fluid density by the sg of thefluid relative to the density of water (8.34 lbs./gal.). Gasoline with a sg = .72, weights approximately 6.0 lbs./gal.(.72 x 8.34 lbs./gal.)

Pressure and HeadPressure. Pressure is a force per unit area and is commonly expressed in terms of pounds per square inch (psi).The pressure existing at any point in a liquid at rest is caused by the atmospheric pressure exerted on the surface,plus the weight of liquid above the point in question and/or any externally applied pressurization. The pressure isequal in all directions and acts perpendicularly to any surface in contact with the liquid.

Head. Head is a term used to describe pressure in terms of height of liquid above given datum point. Therelationship between pressure and head is a function of the fluids specific gravity (sg). The concept is bestillustrated by example as shown in Figure 2-12.

In the vernacular of the pump industry, when the term “pressure” is used it generally refers to units in psi; whereas,“head” refers to feet of the liquid being pumped.

2-15

sg = 141.5/131.5 + API degree sg = 145/145 - degree Baume


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Section 2B Hydraulic Fundamentals2-16

Figure 2-12: Pressure - Head - Specific Gravity Relationships

H = 115.5 ft.

60 psi

sp gr = 1.2

H = 115.5 ft.

50 psi

sp gr = 1.0

35 psi

sp gr = .70

H = 96 ft.

50 psi

sp gr = 1.2

H = 115.5 ft.

H = 165 ft.

50 psi

sp gr = 1.0

50 psi

sp gr = .70

Head and pressure are related mathematically by the formula:

A column of water (sg = 1.00) one foot high (1.0 ft. of head) will produce a pressure of 0.433 psi at the base of thecolumn. A pressure of 1.0 psi at the base of a column will result in a water column 2.31 ft. in height.

The head (expressed in feet) at the base of a given column of liquid will always be the same, regardless of what liquidis used. The pressure (expressed in psi) at the bottom of the column will vary with the specific gravity of the liquid.Pressure and head are simply a different way of expressing the same value in the most advantages form for thehydraulic application.

Gauge and Absolute Pressure. “psig” and “psia” are the abbreviations for pounds per square inch - gauge andpounds per square inch - absolute. Zero psig is the pressure above atmospheric pressure, which is 14.7 psia at sealevel. Zero psia is the absolute pressure above a perfect vacuum. A pressure gauge calibrated to read in psia wouldshow a reading 14.7 psi greater than a gauge calibrated in psig. A through understanding of this difference isessential for calculating involving NPSH, suction lift, siphons, etc. When the term psi is used alone, it refers to psig.

Head (ft.) = psi (2.31)

Pressure-head relationship of identical pumps handling liquids of differing specific gravities

Pressure-head relationship of pumps delivering same pressure handling liquids of differing specific gravity.


Section 2


Velocity Head. The above discussion refer to static head, velocity head is the energy in the fluid as a result of fluidmomentum and can be calculated using the formula:

The velocity head is normally neglected in the total head calculation for applications involving submersible pumps.It is only a small part of the total head and is typically disregarded except in extremely low head applications.

Fluid FlowWater is practically incompressible with a compressibility of approximately .33% volume reduction for every 1000psi. Because of the relative incompressibility of water, there is a definite relationship between the quantity of liquidflowing in a conduct and the velocity of flow. The relationship is known as the continuity equation and isexpressed as follows:

Where;

Q = Capacity in cubic feet per second (cfs)A = Area of conduit in square feet (sq. ft.)V = Velocity of flow in feet per second (fps)ID = Internal diameter of circular conduit/pipe (in.)

Volume. The standard volume unit for water supply application in the U.S. in the gallon (gal.) and to a lesserdegree the cubic foot (cu. ft.). The rate of flow is expressed in gallons per minute (gpm) and in cubic feet persecond (cfs) where large volumes of water is being moved.

Volume flow rates in gpm can be converted to a mass flow rate in pounds per hour (lbs./hr.) utilizing the formula:

Note: 1. Specific gravity (sg) corrections for temperatures are not normally required at normal groundwater temperatures. Refer to Table 2-18 should precise sg values be required.

2. * One gallon of water weighs 8.43 lbs./gal. @ 60°F; therefore, 60 x 8.34 = 500

Vapor PressureThe best way to understand vapor pressure is to consider a container which is completely closed and half filledwith liquid. If the container is completely evacuated of air, a portion of the liquid will vaporize and fill the upperhalf of the container with vapor. The pressure of the vapor in the upper half of the container, is by definition, thevapor pressure of the liquid at that liquid temperature. The concept of vapor pressure is illustrated in Figure 2-13.

Vapor pressure is measured in pounds per square inch absolute (psia) and is generally a function of thetemperature of the liquid. It can be thought of as the pressure at which the liquid molecules begin to separate,forming a vapor. At 60°F, the vapor pressure of water is approximately 0.3 psia. At the boiling point of water,(212°F), the vapor pressure is equal to atmospheric pressure, 14.7 psia.

A listing of vapor pressure vs. temperature for water over a temperature range of 32 -300°F is provided in Table 2-18.

2-17

Velocity Head (ft.) = (sg) (fluid velocity in ft./sec.) /64.4

Q = AV or V = Q/A = 0.410 (gpm)/(ID)

gpm = (lbs./hr.) /* 500 (sg)


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NPSH (Net Positive Suction Head)NPSHR. For a pump to operate satisfactorily, the pumped liquid must be supplied to the eye of the first stageimpeller at a suction pressure (NPSH) sufficient to prevent vaporization as the liquid enters the impeller. Eachimpeller design has its own unique requirement for NPSH. This varies with the capacity being pumped and thespeed of the pump. Curves or data is normally furnished by pump manufacturers showing the Required NPSH(NPSHR) for the pump at various speeds. If adequate NPSH is not available to a pump, the result is a loss of headand efficiency, pitting and erosion of the leading edge of the impeller, noise, and eventual failure.

NPSHA. When the pump NPSHR is established, the next step is to determine the amount NPSH which will beavailable to the pump. This is known as available NPSH (NPSHA). The formula for determining NPSHA is givenbelow:

Where;

Ha = Absolute pressure on the liquid surface of the water (in feet of liquid).Hvp = Vapor pressure of the liquid at the pumping temperature (in feet of liquid).Hf = Friction losses in the piping from the supply tank to the pump (in feet of liquid)Hs = Distance of liquid level above or below the impeller eye.

(If level is above eye, Hs will be positive. If level is below the eye, Hs will be negative)

Refer to Figure 2-15 for typical NPSHA submersible application scenarios. Figure 2-14 illustrates several commonsuction conditions commonly encountered in the water supply industry.

Ha will be equal to 33.9 feet for water at sea level (33.9 feet of water is equal to the atmospheric pressure of 14.7psia). Remember to allow for the specific gravity of the liquid in calculating Ha if necessary. A liquid with a specificgravity of 2.0 and .9 have an Ha of 17 feet and 68 feet respectively at sea level.

It is estimated that 75% of all pump problems are due to improper intake / suction conditions. Issues whichcommonly contribute to suction problems are; cavitation, insufficient submergence, vortexing and entrained gas.Cavitation is a direct result of insufficient NPSH. Increasing submergence can improve problems related toinsufficient NPSH, as well as reduce the potential for vortexing. Problems associated with entrained gas can, insome cases, be improved with increased submergence.


Figure 2-13: Vapor Pressure Illustrated

PressureVapor

Liquid

Water

Vapor

14.7

0.30

32 60 212TEMPERATURE °F

VAP

OR

PR

ES

SU

RE

Vapor Pressure Vapor Pressure of Water vs. Temperature

NPSHA = Ha - Hvp - Hf +/- Hs


Section 2

Section 2B Hydraulic Fundamentals 2-19

Example 2-1: Available NPSH (NPSH) calculation

Given: (1) Elevation (ASL) = 1,000’ (2) Water Temp. = 80°F(3) Capacity (Flow) = 500 gpm (4) Suction Head = 20’(5) Steel Suction pipe length/diameter = 20’ / 6”

Analysis: Based on flooded intake condition as illustrated in Figure 2-14 (diagram A) above.

1. Ha = 32.8’ (from Table 2-15 @ 1000’)2. Hvp = 1.17’ (from Table 2-18 @ 80°F)3. Hf = .61’ (from Table 7-10 and Table 7-14)

• Hf = (1.66’/100’) 20’ + (1.66’/100) 17’ = .33’ (pipe loss) + .28’ (elbow loss) = .61’4. Hs = 20’5. NPSHA = 32.8’ - 1.17’ - .61 + 20’ = 51’

Note: (1) If the NPSH requirements (NPSHR) of the pump is less than the calculated NPSHA value of 51’, thepump will operate satisfactory.

(2) If the suction head in the above example, were changed to a suction lift as illustrated in Figure 2-14 (diagram B) above, NPSHA = 11’ (Ha - Hvp - Hf - Hs)

Figure 2-14: NPSHA and Suction Conditions (Non-Submersible Pump)

Totalhead

Dischargehead

Suctionhead

Totalhead

Suctionlift

Statichead

A. Flooded Suction B. Suction Lift

NPSH = Ha + Hs - Hvp - Hf NPSHA = Ha -Hs - Hvp - Hf


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Figure 2-15: Typical Submersible Pump NPSHA Senarios

Hs (Submergence)

AtmosphericPressure (Ha)

Water Level (WL - Pumping)

Impeller Center Line (Datum)

Hs

AtmosphericPressure (Ha)

Datum

WL

Hf (Friction Loss)

Hs

Datum

WL

Hf (Friction Loss)

Internal Pressure (Pa)Ha = Pa/2.31 for fresh water

A. Submerged Intake

B. Flooded Intake

C. Pressurized Intake

NPSHA = Ha (ft.) - Hvp (ft.) + Hs (ft.)

NPSHA = Ha (ft.) - Hvp (ft.) - Hf (ft.) + Hs (ft.)

NPSHA = Ha (ft.) - Hvp (ft.) - Hf (ft.) + Hs (ft.)


Section 2


Power, Efficiency and EnergyPower. Power is defined as a time-rate of doing work. Horsepower (Hp) is the most common unit used to expresspower requirements for pumping equipment in the United States. One Hp is equal to the work performed overtime when a weight of 33,000 lbs. is lifted on foot in one minute (ie. 1 Hp = 33,000 ft.-lbs./min. or 550 ft.-lbs./sec.).

WHp. Horsepower in pumping applications is a function of the fluid density, flow (Q or m) and total head (TH orH) or differential pressure to be developed. Taking water as the basis for calculation at 70∞F and atmosphericpressure (sg = 1.0 and density = 8.34 lbs./gal.), the following formulas can be used to express hydraulic/theoreticalHp (usually called water Hp (WHp) in water supply applications):

where; m = mass flow (lbs./min.)or, Q = flow (gpm)

H = TH = total head (ft.)

Note: (1) sg = 1.0 for most water supply applications and is normally not included(2) 3960 gal.-ft./min. = (33,000 lbs.- ft./min.) / (8.34 lbs/gal.) = 1.0 Hp(3) WHp = (gpm x psi) / 1714

BHp. The actual or brake horsepower (BHp) of a pump will be greater than the WHp by the amount of lossesincurred within the pump through friction, leakage and recirculation. Such losses are accounted for by the pumpefficiency (PE). The BHp (shaft Hp - power delivered to the pump) can be expressed as:

where;or PE = Pump efficiency

Note: (1) PE = WHp / BHP,(2) BHp = gpm x psi / (1714 x PE)

EHp. Electrical Hp input (EHp) to the motor is used for calculating the overall efficiency (OE) of a pumping unitand motor under test conditions. Power and friction losses associated with cable, piping and fittings can beneglected as settings are generally less than 10’.

where;or, or, Em = motor efficiency

Note: 1 Hp = 0.746 kW

IHp. Input horsepower (IHp) and EHp are approximately the same in booster applications, but can verysignificantly as setting depth increases. IHp is used to determine overall plant efficiency (OPE) and takes intoaccount all installation losses (pump, motor, friction, cable, etc.). IHp can be expressed as follows.

where;or, Hf = friction loss (ft.)

Hp (cable) = cable loss (Hp)

Note: If a variable frequency drive (VFD) is used between the pump and motor, the VFD efficiency should beincluded in the numerator. Typical VFD efficiencies range from 90-98%.

Efficiency. The efficiency concepts developed previously in the discussion of Horsepower are summarized asfollows:

Pump efficiency (PE). PE is the ratio of energy delivered by the pump to the energy suppliedto the pump shaft.

2-21

WHp = m x H33,000

WHp = Q x H x sg3960

BHp = WHp/PE BHp = Q x H x sg3960 x PE

EHp = WHpOE

EHp = BHpEm

EHp = Q x H x sg3960 x PE x Em

IHp = WHpOPE

BHp = Q x (H + Hf) + Hp (cable)3960 x PE x Em

PE = WHp/BHp


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Overall efficiency (OE). OE is the ratio of the energy delivered by the pump to the energysupplied to the motor input terminals, and generally takes into account only motor and pumpefficiency (ie. OE = PE x ME).

Overall plant efficiency (OPE). OPE is the ratio of the energy delivered by the pump to theenergy supplied to the entire pumping plant, and takes into account all installation losses.

The subject of efficiency is discussed in greater detail in Section 2D under the general heading of “testing”.

Energy. Energy is normally expressed in terms of kilowatt - hours (kWh) per unit volume. Typical units of measureand the associate calculations are presented as follows.

or

The subject of energy usage and the associated cost of pumping are discussed more completely in Section 2D,under the general heading of “power consumption and cost”.

ViscosityThe viscosity of a fluid (liquid or gas) is that property which offers resistance to flow due to the existence ofinternal friction within the fluid.

Pumping viscous liquids can present difficult problems for centrifugal pumps. Fortunately, the viscosity changesrelative to water in the temperature range commonly encountered in water supply applications (50 - 85°F) can beneglected.

Water is classified as “Newtonial fluid,” which exhibits decreasing viscosity with temperature. Viscosity changes overthe temperature range of interest has no direct impact on pump performance; however, pipe friction losses decreasefrom a maximum value at 32°F by approximately 40% over the temperature range of 32 - 212°F. Piping friction losstables for water are typically based on a reference temperature of 60°F and require no correction for viscosity formost water supply applications. Refer to Table 2-1 below, for a listing of viscosity values for water at varioustemperatures at sea level.


OE = WHp/EHp

OPE = WHp/IHp

kWh/1000 gal. = H x 0.00315OPE

kWh/acre-ft. = Q x H x 1.032OPE

Table 2-1: Viscosity of Water from 32° to 212°F @ Sea Level

Temp. Absolute Viscosity Kimematic Viscosity Specific

°F °C Centipoises Centistokes SSU ft./sec. Gravity

32 0 1.79 1.79 33.00 0.00001931 .9999

40 4.4 1.54 1.54 32.3 0.00001664 1.000

50 10.0 1.31 1.31 31.6 0.00001410 .9997

60 15.6 1.12 1.12 31.2 0.00001217 .9990

70 21.1 0.98 0.98 30.9 0.00001059 .9980

80 26.7 0.86 0.86 30.6 0.00000930 .9960

90 32.2 0.77 0.77 30.4 0.00000826 .9950

100 37.8 0.68 0.69 30.2 0.00000739 .9931

120 48.9 0.56 0.57 30.0 0.00000609 .9888

140 60.0 0.47 0.48 29.7 0.00000514 .9833

160 71.5 0.40 0.41 29.6 0.00000442 .9773

180 83.0 0.35 0.36 29.5 0.00000385 .9702

212 100 0.28 0.29 29.3 0.00000319 .9592


Section 2

Section 2B Hydraulic Fundamentals 2-23

A fluid can be broadly classified as Newtonian, where viscosity remains constant regardless of changes in shear rateor agitation. As pump speed increases, flow increases proportionately. Liquids displaying Newtonian behaviorinclude water, mineral oils, syrup, hydrocarbons and resins.

Viscosity is described in terms of absolute (dynamic) or kinematic values. Absolute viscosity is technically describedas the shear stress (force) divided by the shear rate (velocity gradient - max fluid velocity divided by the distancefrom pipe wall). Kinematic viscosity is a product of the absolute viscosity divided by density of the fluid and is themost common viscosity reference in the pump industry.

One of the most common units of measure of kinematic viscosity is Saybolt seconds. This refers to the length oftime it takes for a measured quantity of fluid at a specific temperature to drain from a container with a measuredorifice in the bottom. Water has a viscosity of approximately 31 Saybolts seconds universal (SSU) at 60°F. Kinematicviscosity is also commonly expressed in metric units as stokes or centistokes.

Pumping Viscous Liquids with Centrifugal Pumps. Centrifugal pumps are generally not suitable for pumpinghighly viscous liquids. They can be used to pump liquids with viscosities less than 2000 SSU. The volume andpressure capabilities of the pump will be reduced with increasing viscosity. Table 2-2 lists the percent increase inpower required along with the percent reduction in flow and head when pumping liquids of increasing viscosities.

Table 2-2: Viscosity Affect on Pump Performance

Viscosity (SSU) > > > > 30 100 250 500 750 1000 1500 2000

Flow reduction (gpm) % – 3 8 14 19 23 30 40

Head reduction (feet) % – 2 5 11 14 18 23 30

Horsepower increase % – 10 20 30 50 65 85 100

Note: Fluid should be corrected for specific gravity prior to applying viscosity corrections


Sect

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2C HYDRAULIC RELATIONSHIPS

Affinity Laws - Pump SpeedIn a standard centrifugal pump the characteristic curve for the pump can be changed by either (1) keeping thespeed constant and varying the impeller diameter or by (2) keeping the impeller diameter constant and varying thespeed. The relationship between these variables are known as the affinity laws and can be expressedmathematically as shown in Table 2-3 below:

Section 2C Hydraulic Relationships2-24

Table 2-3: Affinity Laws - Speed / Diameter Relationships

(1) Imp. Dia. Constant / Speed VariableQ1 / Q2 = N1 / N2H1 /H2 = (N1)2 /(N2)2

BHp1 / BHp2 = (N1)3 / (N2)3

(2) Speed Constant / Imp. Dia. ConstantQ1 / Q2 = D1 / D2H1 / H2 = (D1)2 / (D2)2

BHp 1 / BHp2 = (D1)3 / (D2)3

Q1, H1, BHp1, D1 and N1 = Initial Capacity (gpm), Head (ft.), Brake Horsepower (Hp), Diameter (in.) and Speed (rpm).

Q2, H2, BHp2, D2 and N2 = New Capacity (gpm), Head (ft.), Brake Horsepower (Hp), Diameter (in.) and Speed (rpm).

In submersible pump applications, where the pump can only be driven by an electric motor, and impeller trimming(diameter changes) are commercially impractical, speed changes are most commonly accomplished through the useof a variable frequency drive (VFD). Frequency (Hz) can be interchanged with the speed (N) in the application ofthe affinity laws, as they are directly proportional. This relationship makes it possible to calculate pumpperformance with reasonable accuracy, at any speed, if the performance at the initial speed/ frequency is known.The use of frequency in predicting pump performance is illustrated in Table 2-4 below:

Table 2-4: Affinity Laws - Frequency Performance Relationship

(3) Imp. Dia. Constant / Frequency VariableQ2 = (Hz2 / Hz1) Q 1Hz2 = (Hz2 / Hz1)2 H21BHp2 = (Hz2 / Hz1)3 BHp1

Q1, H1 and BHp1 = Initial Capacity (gpm), Head (ft.)and Brake Horsepower (Hp)

Q2, H2 and BHp2 = New Capacity (gpm), Head (ft.)and Brake Horsepower (Hp)

The affinity laws are theoretical and do not always give the same results as an actual test, as they do not take intoconsideration various dynamic factors such as intake losses and motor slip. They do serve as an excellent guide forcalculating unknown performance characteristics form known values when test data is not available. These laws(frequency variable) are summarized as follows:

1. The capacity varies directly with the speed. (Q α Hz)2. The head varies with the square of the speed. (H α Hz2)3. The horse power varies with the cube of the speed. (BHp α Hz3)4.. Efficiency remains approximately the same between the original and corresponding H-Q performance point at

the new speed.

Efficiency is assumed to remain the same for calculation purposes (variations in efficiency is likely to occur outsidethe published speed rating based on actual test). The affinity law relationships are primarily applicable to centrifugalpumps with specific speeds (Ns) of 3500 or less. Pumps utilizing impellers with Ns greater than 3500 (mixed / axialflow designs), can not be as accurately estimated using the affinity laws.

Suction Specific Speed (S). Suction specific speed, like impeller specific speed, is a parameter for indexinghydraulic design used to describe the suction capabilities and characteristics of a pump impeller. Suction specificspeed (S) can be expressed mathematically as follows:

where; N = speed (rpm) @ full load (single stage)Q = flow (gpm) @ BEPNPSHR = Net Positive Suction Head Required (ft.) @ BEP

S is a number used for labeling impellers relative to their NPSH requirement. It is independent of the pump sizeand impeller (operating) specific speed (Ns). S is primarily a impeller design parameter and is not a important factorin the application of low capacity (< 3000 gpm) submersible pumps, and is discussed for completeness. Suctionspecific speeds (S) can range from 3000 - 20,000, depending on the impeller design, speed, capacity and conditionof service. Good quality commercial pump designs fall into the S range of 7,000 - 10,000.


Section 2

Section 2C Hydraulic Relationships

Specific SpeedImpeller Specific Speed (Ns). In 1915, a European by the name of R. Cameron introduced a characteristic todescribe the hydraulic design type of turbines and pumps. This characteristic is referred to as “Specific Speed” andis defined as the speed at which a given impeller would operate if reduced proportionally in size, so as to deliver aflow of one gallon per minute at one foot of head. Specific speed (Ns) can be calculated as follows:

where; N = speed (rpm) @ full load (single stage)Q = flow (gpm) @ BEP (best efficiency point)H = head (ft.) @ BEP (single stage)

The Ns of a given pump is the same at all rotative speeds. A low specific speed indicates a pump designed for alow capacity and a high pumping head. Conversely, a high Ns pump is one designed for a high capacity and a lowpumping head.

Ns serves to inter-relate pump hydraulic performance characteristics (flow, head, speed, etc.) and impeller physicaldimensions in such a manner to make equipment design and application more systematic. It can also be used as ageneral criterion for predicting pump suitability under unusual operating scenarios, such as entrained gas andminimum NPSH conditions. Figure 2-16 and 2-17 can be used to relate Ns to impeller type and performanceexpectations.

2-25

Ns = N Q / (H) .75

Table 2-5: Converting 60 Hz to 50 Hz Performance

50-Cycle Head = 69.44 % x 60-Cycle Head50-Cycle Capacity = 83.33 % x 60-Cycle Capacity

50-Cycle Horsepower = 57.80 % x 60-Cycle Horsepower50-Cycle Efficiency = Same as 60-Cycle Efficiency

Figure 2-16: General Specific Speed Relationships

Ns 500 - 3000 1500 - 4500 4500 - 8000 8000 >

Type Radial Francis Mixed Flow Propeller

Head (ft.) 100 - 150 20 - 150 35 - 65 1 - 40

Dia. Ratio (D2/D1) 2 + 1.5 1.3 - 1.1 1.0

Efficiency (%) 82-47 87 - 52 87 - 74 90 - 77

Impeller Configuration

S = N Q / (NPSHR) .75


Sect

ion

2


Figure 2-17: Pump Efficiency vs. Specific Speed and Pump Size

500 1000 2000 3000 4000 10,000 15,000

PUMP SPECIFIC SPEED (Ns)

100

90

80

70

60

50

40

EF

FIC

IEN

CY

– P

ER

CE

NT

100

200

5001000 3000

10,000

Over 10,000 gal./min.

Radial/Francis Centrifugal

Mixed Flow

Axial Flow

AxialMixed FlowFrancisRadial

Speed Torque RelationshipsThe typical speed - torque curve for most centrifical pumps is illustrated in Figure 2-18. The relationship is valid forall centrifugal pumps in the low to medium specific speed range (Ns = 3500 or less). A plot of pump speed - torquerequirements vs the driving motor speed - torque capabilities is often of interest to insure;

(1) Fixed speed applications - The motor has sufficient torque to set the load in motion at start-up.(2) Variable speed / frequency applications - Adequate torque is available to drive the pump at various loads and

operating frequencies, when voltage is clamped.

The electric submersible motor (pump driver) must be capable of supplying more torque at each successive speed,from zero to full load, than required by the pump to reach full speed. This condition is seldom a problem with thetypical submersible induction motor. Improperly applied reduced voltage starting equipment and/or improperlysized cable can create start-up torque problem, as a result of low motor terminal voltage. Voltage is related tostarting torque as follows: (T α V2).

Using a nominal 2-pole motor speed of 3500 rpm (1760 rpm for 4-pole motors) and the calculated BHp. Pumptorque can then be calculated, plugging into the formula below.

where; T = Torque (ft. - lbs.)BHp = Brake Horsepower (Hp)rpm = Speed (rev. per min.)

It is normally acceptable to estimate a pump’s full load torque requirement using the manufactures published H-Qdata, where full load speed and BHp at peak efficiency is usually listed. Full load (speed) torque are typicallycalculated at the best efficiency point (BEP). Torque varies with the square of the speed; therefore, when full loadtorque is known - torque at other speeds can be calculated using Figure 2-18 or the following relationships.

T = (5250) (BHp)/rpm


Section 2


1.33 speed - multiply full speed torque by 1.778 .75 speed - multiply full speed torque by 0.563.50 speed - multiply full speed torque by 0.250.25 speed - multiply full speed torque by 0.063

At zero speed the torque is theoretically zero; but the motor must overcome rotating element inertia, bearing frictionand a static head load in order to start the pump shaft turning. This requires a torque at zero speed ranging from 21/2 percent to 15 percent of the full load torque value. The BHp requirements for most centrifugal pumps used forsubmersible water supply applications at shut-off (0 gpm) is approximately 60% of the full load value.

High specific speed, axial flow pumps have different speed torque characteristics as a result of high horsepowerrequirements at shut-off. Reciprocating pumps generally require between 125% and 25% of full load running torqueto start, depending on the load on the pump at start-up. Starting a pump during backspin should be avoidedwhenever possible, if backspin can not be prevented, the manufacture should be consulted.

Torque & Column/Riser Pipe. Steel pipe should have taper thread (NPT) for torque resistance and ease of installation.Thread make-up torque should be sufficient to prevent unscrewing as a result of motor torque. If straight thread pipeis used, each joint should be secured to resist motor torque. Small submersible units installed using plastic pipe orhose, can sometimes be equipped with a motor torque arrestor to prevent unscrewing or excessive flexing.

2-27

Figure 2-18: Typical Pump Speed Torque Curve

0 10 20 30 40 50 60 70 80 90 100

% SPEED

100

90

80

70

60

50

40

30

20

10

0

% T

OR

QU

E

Break-AwayTorque

TORQUE (FT-LBS) = (5250)(BHP)RPM


Sect

ion

2

System Head CurveWhen a system end point and / or overall system operating pressure range has been established, and flowrequirements change appreciable based on demand, the system head vs capacity can be modeled through thedevelopment of a system head curve. The head losses within a system will change based on the flow forced into itby pumping. The system head (Hspf) is typically made up of three components and is usually estimated from thepump discharge forward. The three components of Hspf are; (1) Static Head, (2) Pressure Head and (3) FrictionHead, as illustrated in Figure 2-19 below.


Figure 2-19: System Head Curve Illustration

Static Head(Hs)

Frictious Head (Hf)

Pressure Head (Hp)

**

*

Measurement pt.for Total HeadSystem End pt.

*** FLOW (GPM)

HE

AD

(F

T.)

OR

PS

I

Hs

Hp

Hf

SystemHead(Hspf)

The use of a system head curve is crucial for proper submersible pump selection in various process and boosterapplications. The concept is particularly important, where system capacity requirements are highly variable (Q max >1.30 Q avg and / or Q min < .70 Q avg.). In such cases, multiple pumps are often used in parallel or are controlledthrough a variable frequency drive (VFD). Pump selection is based on matching the system head curve (pluspumping lift), with the pump(s) H - Q performance. In deep well - fixed speed pumping applications, the systemcurve is less important as a direct design tool. In such cases, system head requirements are normally specified as asingle point at a capacity that can be sustained continuously by the well. The system head design point can be thesame as the above ground head (AGH) component of the pump total head (TH) used in the pump selection process.The AGH value is typically slightly greater then the optimum system pressure to over come discharge header losses(check valve, flow meter, etc.), and is generally centered around a cut-in / cut-out system pressure.

In developing the system curve, static (Hs) and pressure (Hp) head stay relatively constant, within the allowablesystems operating range. Hs and Hp do not change with flow and are independent of friction head (Hf). Hf througha piping system varies approximately with the square of the flow, making it only necessary to perform detailed Hfloss analysis / calculation once, at one flow rate. Friction loss approximations at other flow rates can be made byapplying the square law relationship.

The typically guide line steps employed in developing a system curve are:

1. Determine minimum, average and maximum (peak) system capacity requirements

2. Establish optimum Hs and Hp head system requirements. Permissible variations in Hs and Hp head (systempressure operating range) should be considered to establish a allowable operating envelope.

3. Determine friction losses at zero, minimum, average, maximum and intermediate flow points as necessary.

4. Tabulate data and plot system curve


Section 2

Section 2C Hydraulic Relationships 2-29

The system curve development process is illustrated by example as follows:

Example 2-2: System - Head Development Illustration

Given. (1) capacity - system minimum, average and maximum flow was established at 500 (Q min), 750 (Qavg) and 1500 (Q max) gpm respectively. (2) pressure - optimum system static (Hs) and pressure (Hp) areestimated at 20’ and 115’ (50 psi) respectively. Hs is fixed at 20’, while allowable variance in Hp is + 10 psi(23’) / - 20 psi (46’). (3) friction loss - friction head (Hf) was calculated at 11.25’ @ 750 gpm.

Analysis. (1) Tabulate performance data using given information and previously developed guide lineprocedures:

Table 2-6: System - Head Curve Development Table for Example 2-2

Q Hf Hs Hs Hs Hp Hp Hp Hspf Hspf Hspf(min) (max) (min) (max) (min) (max)

0 0 20 – – 115 – – 135 – –0 – 20 – – 69 – – 89 –0 – – 20 – – 138 – – 158

500 5 20 – – 115 – – 140 – –5 – 20 – – 69 – – 94 –5 – – 20 – – 138 – – 163

750 11 20 – – 115 – – 146 – –11 – 20 – – 69 – – 100 –11 – – 20 – – 138 – – 169

1000 20 20 – – 115 – – 155 – –20 – 20 – – 69 – – 109 –20 – – 20 – – 138 – – 178

1500 45 20 – – 115 – – 180 – –45 – 20 – – 69 – – 134 –45 – – 20 – – 138 – – 203

1750 61 20 – – 115 – – 196 – –61 – 20 – – 69 – – 150 –61 – – 20 – – 138 – – 219

Notes: a. Hf @ 500 gpm = 11.5’ (500 / 750) = 5’ / Hf @ 1000 gpm = 11.5’ (1000 / 750) = 20’b. Hspf (min) = Hspf - 46’ / Hspf (max) = Hspf + 23’c. Hspf = Hs + Hp + Hf


Sect

ion

2


Figure 2-20: System - Head Curve Plot for Example 2-2

0 250 500 750 1000 1250 1500 1750

Q (CAPACITY - GPM)

200

180

160

140

120

100

80

Hsp

f (T

OTA

L H

EA

D -

FT.

)

System - Head(upper limit)

System - Head(optimum)

System - Head(lower limit)

(2) Plot System Curve using data tabulated.

Deep set well pumps in well applications, where pumping water levels (PWL) are highly variable as a result of lowwell yields or parallel operation, the head required to pump water to the surface can be greater and more variablethan the surface system head requirements. The variable lift characteristics, combined with changes in system headcan create a significant application problem where single or parallel (fixed speed) well pumps are used. Suchapplication lend themselves to the use of variable speed (frequency) control for efficiency optimization andflexibility.


Section 2


Parallel and Series OperationParallel Operation. When the pumped flow requirements are widely variable, it is often desirable to install severalsmall pumps in parallel rather than use a single large one. When the demand drops, one or more smaller pumpsmay be shut down, thus allowing the remainder to operate at or near peak efficiency. If a single pump is used at alower demand, the discharge must be throttled to match the system curve - wasting energy if not controlled by aVFD. Multiple small pumps provide system flexibility and redundancy. The failure of one unit, may cause aninconvenience, but does not shut - down the system. System maintenance and repair is made easier and does notcreate operational problems if performed during slack periods.

The action of centrifugal pumps operating in parallel can be predicted by the addition of their characteristic curves.This relationship is true whether the curves are identical or not, and is illustrated in Figure 2-21.

2-31

Figure 2-21: Parallel Pumping General Characteristics

H

A

C

CB

D

Q

E

One pump Two pump

A

CF

B

D E

Two pumps

Pump no. 1 Pump

no. 2

Diagram A - Two Identical Pumps Diagram B - Two Dissimilar Pumps

Water systems with more than one pumping plant actually operate in parallel; however, they are typically located atsuch a distance from one another so that they can be considered individually. The focus of this discussion is on amultiple pump booster situation, feeding a specific quantifiable usage. In planning such installations, the systemhead curve should be developed and drawn as a part of the pump selection and application process. Pumpsutilized in parallel service should have a steep continuously rising Head - Capacity (H-Q) characteristics. The designprocess using fixed speed pumps on cascade controls are illustrated below.

Example 2-3: Fixed Speed - Parallel Pumping System Illustration (3 Pumps)

Given. The system curve developed in Example 2-2. Three identical pumps are available for booster systemincorporation; with individual H-Q ratings of 500 gpm @ 140’ at the best efficiency point (BEP).

Analysis. (1) Super - impose pump performance on system curve by adding horizontally the individual pumpcapacities at the same head.


Sect

ion

2


Figure 2-22: Fixed Speed - // Pump System - Head Curve Illustration for Example 2-3

0 250 500 750 1000 1250 1500 1750

Q (CAPACITY - GPM)

200

180

160

140

120

100

80

HS

PF

(TO

TAL

HE

AD

- F

T.)

UpperOperating Limit

OptimumOperating Limit

LowerOperating Limit

H-Q, 1 pumpH-Q, 2 pumps

in parallel

H-Q, 3 pumpsin parallel

Pump BEP

Pump – "run out flow"

Note: Pump lifts associated with submersible or vertical turbine boosters, are considered to be negligible in the above example.

The three pump system curve fit will work within the allowable operating limit as illustrated in Example 2-3. Better fits are possible using different pump sizes and combinations; however they often reduce flexibilityfrom a interchangeability stand point. A three pump combination of different H-Q ratings (ie. (A) 500 gpm @140’, (B) 1000 gpm @ 150’, (C) 250 gpm @ 150’) may provide a better fit with less variation in pressure. Theuse of a VFD will serve to provide greater system flexibility and pressure maintenance closer to the optimumrequirements.

Parallel Pumping Efficiency and Flow Relationships.

where;

Q = Capacity in gpm, H = Total Head (System Head + Pump Lift + Losses) in ft.

Parallel Well Pump Applications. The guide lines established for parallel booster systems also apply generally toparallel well pumps. The wells must be located within close proximity to one another or the pumps must beinstalled in the same well. The variation in water level with flow must be carefully considered, in addition to thesystem head requirements, in the selection of pumping equipment. Parallel well pump operations are generallyconfined to shallow large diameter wells with high specific capacities.

Eff. = 3960 (BHp @ QA + QB + Qc)

(QA + QB + Qc) H QT = QA + QB + QC


Section 2

Section 2C Hydraulic Relationships 2-33

Series Operation. Multiple pumps in series may be used when liquid must be delivered at high pressure. Seriesoperation is most commonly required when:

1) The system head and lift requirements can not be met at the required capacity with a single unit (ie.submersible pumping equipment larger than well diameter).

2) A system with adequate capacity, has expanded beyond the original pressure design constraints, requiring aboost in pressure to deliver water to the most distant points in the system at acceptable pressure levels underpeak flow conditions.

The focus of this discussion is on pumps that are in such close proximity to each other so that there combinedperformance can be determined by adding vertically the heads at the same capacities. Siting the individual pump H-Q performance used in example 2-3 of 500 gpm @ 140’, the combined performance of two of these units in seriesis 500 gpm @ 240’.

Series Pumping Efficiency and Head Relationships.

where;

Q = Capacity in gpm, H = Total Head (System Head + Pump Lift + Losses) in ft.

Series operation is not the same as booster service from a application standpoint. Pumping equipment operated incompound series must be closely stop / start coordinated to prevent water hammer, and should have there BEP asclose to the same capacity as possible for efficient operation. In -line booster service is distinguished fromcompound series operation in that there is usually some distance between pumping units and in-take (suction)pressures at each pump in sequence is generally substantially less than the discharge pressure of the precedingpump or system. In-line systems are typically used if two or more pressure zones are to be supplied from the samesource. Applications requiring pressure boosting can be handled efficiently by either method, with consideration ofapplication constraints (ie. pressure limits, space, power availability, etc.).

Eff. = 3960 (BHp @ HA + HB)

Q (HA + HB) HT = HA + HB


Sect

ion

2

Minimum Flow - Temperature RiseMinimum Flow Limitation. All centrifugal pumps have limitations on the minimum flow at which they should beoperated. Minimum flow problems typically develop as a result of excessive throttling and / or improper sizing. Ingeneral, the head-capacity (H-Q) curve of a submersible pump has an inflection point between the best efficiencypoint (BEP) and shut-off. Continuous operation of the pump between shut-off and the inflection point will result inerosion of the impeller because of “recalculation flow”. The minimum flow range is typically identified in somemanner on the manufactures published H-Q performance curves.

The geometry of an impeller is designed for the flow capacity at BEP. When the flow rate is decreased below thedesign capacity, there is excess flow area between the impeller vanes and flow separation occurs. When the flowrate is reduced beyond the inflection point toward shut-off, eddy type flow patterns occur near the leading end ofthe impeller vanes and also near the exit end of the impeller vanes. This eddy type flow pattern of “recirculationflow” can cause severe erosion in the impeller.

The severity of the recirculation problem varies with several factors; (1) The higher the specific speed, the greaterthe recirculation, (2) The higher the design head for a given impeller diameter, the greater the recirculation and (3)The larger the impeller eye for a given design flow, the stronger the recirculation.

Pump damage as a result of continuous minimum flow operation may be noticeable within one to six months. Theminimum capacity for operating a pump continuously without noticeable erosion in the impeller is called the“minimum continuous flow” of the pump. In the presence of liquids containing abrasive particles such as sand,pump life can be reduced to weeks. The recirculation process allows for repeated abrasive attack on the impellerby the same particles, that would otherwise be discharged after one pass. In addition to erosion, other problemsassociated with operation below the minimum flow limit include; increased axial thrust, noise, vibration andtemperature.

The minimum flow inflection point for a particular pump is derived from tests. Recirculation consideration aregenerally used to establish the minimum flow range for a given impeller design, although other issues such asdownthrust may dictate the actual minimum flow duty point. As a rule of thumb, a minimum flow limit of 25, 50and 70% of the flow at BEP should be used for pumps with individual capacities of 100, 1000 and 3000 gpm or lessrespectively. The rule of thumb only applies in the absence of manufacture data. If prolong operation in theminimum flow region is anticipated, the manufacture should be contacted for specific recommendations. Theminimum flow point varies with square of the head and is directly proportional to flow.

Many domestic service and special application pumps have no formal minimum flow limitations except fortemperature build-up considerations.

Shut-off Operation (Closed Discharge Valve). Shut-off operation of centrifugal pumps is often necessary to preventwater hammer at start-up and / or shut down in fixed speed applications. Short duration operation at shut-off(minutes) is normally permissible for pumps with low to medium specific speed impellers (Ns = 3500 or less).

Prolong operation at shut-off head will result in rapid failure of pumping equipment. The failure mode is the sameas those sited for minimum flow, but accelerated. The lack of flow for heat dissipation will quickly destroy highcapacity multi-stage pumps.

Minimum Flow Mitigation. Pumps are frequently selected for capacities sufficient to handle maximum or emergencyrequirements. In some cases, pump selection is based on future predicted flows or extremely conservative frictionhead losses. When such criteria is used in the selection process and the pump(s) are run at a fraction of the designrating, problems associated with minimum flow as a result of throttling are likely to occur.

Methods frequently employed to avoid throttling in single pump installations, where flow demands are highlyvariable, include by-pass installation or variable speed (frequency) control. Energy efficiency and operationalflexibility can be maximized through the use of multiple pumps and variable frequency control.

Temperature Rise. Fluid temperature rise with a centrifugal pump can be calculated. Other than a small amount ofpower lost in pump bearings and seals, the difference between the brake horsepower (BHp) and hydraulic



Section 2


horsepower (WHp) developed represents the power losses within the pump itself. These losses are transferred tothe liquid passing through the pump in the form of heat, causing a temperature rise (TRp) in the liquid.

The TRp can be calculated using one of the formulas listed below:

where; TRp = Pump temperature rise in degrees F H = Total head in ft.Ep = Pump (bowl) efficiency @ duty pt.

(expressed as a decimal)Q = Flow @ duty pt. in gpmU = Specific heat of liquid in BTU/lb./F (1.0 for water)sg = Specific gravity (1.0 for water)* sg = 1.0 & U = 1.0

note; 1.0 Hp = 42.4 BTU/min.specific wt water = 8.34 lbs./gal

Discharge water temperatures are higher with submersible pumps, as the heat dissipated by the motor is transferredto the fluid which must pass through the pump for proper operation. The temperature rise (TRm) associated with asubmersible motor acting alone can be approximated as follows:

where; TRm = Motor temperature rise in degrees F Em = Motor efficiency (expressed as a decimal)* sg = 1.0 & U = 1.0

The overall pumped fluid temperature rise (TR) associated with a submersible application can be estimated asfollows:

note; TR (max) should be limited to 35°F* sg = 1.0 & U = 1.0

The heat transfer mode is primarily convection, actual TR will be some what less as a result of radiant heat transfer.The TR issue is generally not a significant application consideration in water supply applications, except in a fewselective circumstances. The heat transferred to the fluid is generally negligible when the submersible pump isoperated within its design range, accounting for less than a one degree TR between the ambient and discharge fluidtemperature.

The minimum continuous flow rating of a centrifugal pump may depend to some extent on the allowable TRpermitted. Pumps fitted with rubber (NBR) sealing and bearing components are rated for a continuous dutytemperature of 104°F (40°C). Fluid TR is a factor to be considered in warm water applications and when prolongedoperation below minimum flow is anticipated. The thermal rating of pump material must be greater than theambient fluid temperature plus TR.

2-35

TRp = BHp (1.00 - Ep) 42.4Q (8.34) sg U

TRp = (BHp - WHp) 5.1Q

TRp = H (1.0 - Ep)780 Ep

*

*

or

or

TRm = (BHp / Em - BHp) 5.1Q *

TR = TRp + TRm = 5.1 (BHp / Em - WHp)Q *


Sect

ion

2

Axial Thrust - Maximum FlowGeneral. Standard vertical turbine type pumps, including submersibles are subjected to axial force which act in adirection parallel to the pump shaft. This force is the combination of the hydraulic thrust developed by theimpellers and the dead weight of the rotating elements of the pump. The rotating element is generally only a smallpart of the axial load of a submersible pump. Accurate determination of axial thrust is crucial in the selection of amotor, establishing internal impeller clearances and operating limits, and diagnosing pump troubles.

The hydraulic thrust developed by a impeller consist of downward or upward components (See Figure 2-23). Thedownward force is due to the unbalance pressure forces across the eye area of the impeller. Counteracting this loadis an upward force (suction side) primarily due to the change in direction of the liquid passing through theimpeller. The resultant of these two forces constitutes hydraulic thrust. In the vast majority of applications this thrustis in downward direction. Axial thrust characteristics for a specific pump is generally provided by the manufacturein the form of a curve or application factor (see Figure 2-24). Thrust data is normally based on a fluid specificgravity = 1.0.


Figure 2-23: Thrust Force Illustration

Downthrust

Upthrust

Figure 2-24: Typical Thrust Curve

0 50% 100% 130%

CAPACITY

TYPICAL THRUST CURVE

+6+4+2

0-2

TOTA

L H

EA

D

TH

RU

ST

IN L

BS

/ F

OO

T O

F H

EA

DHead/CapacityCurve

PeakEfficiency

Efficiency

Thrust Curve

The downthurst in vertical turbine pumps will always be greater than that for a submersible configuration for thesame pump end (bowl assembly), as a result of line shaft weight. In both cases, hydraulic thrust increases as flow isthrottled and varies approximately with the square of the speed at a given flow rate.

Downthrust. As previously mentioned, most vertical pumping equipment operates in downthrust, which is thepreferred operational state. The impeller design is the chief factor in determining the pumps thrust characteristics.High specific speed (Ns) impellers will have higher downthrust characteristics than will lower Ns (radial) impellers.Under some circumstances, it is desirable to increase downthrust so that problems associated with up - thrust canbe avoided when operating to the extreme right of a pumps BEP flow. Downthrust loading can be increasedthrough the use of high Ns or “open” impeller designs. The open / semi - open impeller design varies fromstandard (enclosed) designs in that there is no lower shroud or impeller skirt. Open impeller designs can increasethrust by as much as 50% over enclosed designs at the same rating. Open impeller are rarely used in submersiblepump water supply applications, as running clearances are difficult to adjust for maximum efficiency. Pumpdownthrust requirements over the anticipated operating range should be checked against a motors capacity tohandle the thrust load in high head applications.

Excessive Down Thrust Mitigation. In some applications, hydraulic thrust loads are greater than the thrust handlingcapabilities of the motor. In such cases, mitigation measures often employed to reduce down - thrust are:

1. Hydraulically Balanced Impeller. Hydraulic balance is achieved by reducing the discharge pressure above theimpeller eye through the use of balancing holes and rings. Although hydraulic balancing reduces thrust, it alsodecreases pump efficiency by one to five percentage points due to additional fluid recirculation. Thrust balancedimpellers are normally not required for submersible pump - water supply applications. Thrust balanced impellersare most often used in high speed, high pressure and large pump applications.


Section 2


2. Floating Impeller. The floating impeller design is typically employed in the submersible pump industry at theextreme ends of the application spectrum, ranging from low capacity domestic pumps to extremely high headdownhole pumps used in the oil industry. Floating impellers are not rigidly connected to the pump shaft reducingthe hydraulic thrust loads transferred to the motor thrust bearing. The pump intermediate chambers (stages) aredesigned to carry the thrust load imbalance. In addition to the reduced thrust associated with floating impellers,they are less expensive to assemble and manufacture.

Floating impeller designs are often referred to as a “pancake” type as they typically have a flat upper and lowershroud. The radial pancake design lends itself to better hydraulic thrust balance and transfer of thrust loading to theintermediate chambers. Pump efficiencies and capacities generally range from 50-60% and 5-30 gpm respectively.Grundfos utilizes the floating impeller design in its domestic (spline shaft) submersible product offerings, primarilyfor manufacturing economy.

Upthrust. Upthrust in connection with submersible pumps does not normally occur in the course of normal waterwell service, where an in-line check valve is used. The static fluid column (counter pressure) trapped by a checkvalve will immediately load the pump at start-up, preventing operation to the extreme right of the performancecurve. The same can be said for a vertical turbine pump with a setting depth of 100 feet or more, as the lineshafting provides counter force to upthrust.

In fixed speed applications where there is little or no opposition to flow in the form of a static head load, aabnormally flow condition known as “run-out” will occur at start-up and will persist until system counter pressure isestablished. Under run-out conditions, the pump is likely to be in upthrust. The upthrust condition is generally“momentary”, lasting fractions of a second. The magnitude of the “start-up upthrust” is typically considered to beapproximately 30% of the downthrust value at the pumps BEP. In the case of boosters with suction (intake)pressure, and/or in-line series operation, there can be an additional upward force across the impeller at start-up.

Upthrust Mitigation. Momentary upthrust in submersible applications is mitigated through confinement of theimpellers and/or pump shaft from excessive upward movement. A low friction upthrust stop ring built into thepump to confine movement is typically used. Continuous upthrust can not be handled with an upthrust stop ringalone, as they are not designed for continuous duty in standard products. Grundfos’ larger submersible pumps areequipped with upthrust discs for added protection.

Typical method employed for reducing upthrust as a result or variable flow requirements and/or minimal counterpressure at start-up include; (1) Destaging for a better system match, (2) Discharge valve throttling, (3) Installationof a flow reduction valve or orifice, (4) Speed reduction through a variable frequency drive (VFD), (5) Use ofhigher Ns impellers and (6) the use of multiple lower capacity pumps.

Unmitigated upthrust damage is typified by upper impeller shroud and stop-ring wear.

Maximum Flow. Upthrust consideration are generally used to establish the maximum continuous flow range for agiven impeller design, although other issues such as NPSHA may dictate the actual maximum flow duty point. As arule of thumb, a maximum flow limit of 140 and 130% of the flow at BEP should be used for pumps with individualcapacities of 1000 and 3000 gpm or less respectively. The rule of thumb only applies in the absence ofmanufacturer data. If prolong operation in the maximum flow region is anticipated, the manufacturer should becontacted for specific recommendations. The maximum flow point varies with the square of the head and is directlyproportional to flow.

2-37

2D PUMPING SYSTEM APPLICATION CONSIDERATIONS

Cavitation, Vortexing and SubmergenceCavitation. When the NPSH requirement (NPSHR) of the pump is not met by the NPSH available (NPSHA), thepump is likely to cavitate. Cavitation is a phenomenon which occurs when the pressure of a moving stream ofliquid is reduced to a value equal to or below its vapor pressure, boiling off the liquid. The vaporization of the fluid(water for the purposes of this discussion) normally, in the vicinity of the impeller eye, forms small pockets of freewater vapor (bubbles) which collapse as the liquid moves to a higher pressure zone within the pump. The collapse

of these vapor pockets is so rapid and violent that theforces generated are large enough to cause minutepockets of fatigue failure, pitting metal surfaces that areadjacent to the collapsing vapor/bubbles.

The affects of cavitation vary from mild to extreme. Undermild conditions, the pump may last for many years withonly a slight reduction in efficiency and no noticeablenoise. Extreme cavitation will result in rapid destructionof impellers and/or diffusers in the vicinity of attack (vanetips, etc.) and is normally accompanied by autable(rattling) noise. In the extreme, the pump may lose itsprime as a result of internal gas lock. Other factorsassociated with cavitation are reduced flow, erratic powerconsumption and surging.


Sect

ion

2

Section 2D Pumping System Application Considerations2-38

Figure 2-25: H-Q Deterioration w/Cavitation

H

Q

Performanceat fullcapacity

Performanceaccording todata sheet

Figure 2-26: Cavitation - Vapor Formation Cavitation is not confined to pumping equipment alone. Italso occurs in piping systems where the liquid velocity ishigh and the pressure low. Cavitation should besuspected when noise is heard in pipe lines suddenenlargements of the pipe cross-section, sharp bends,throttled vales or like situations. Cavitation is at a rareoccurrence for submersibles in a water well setting. Incaned booster or vertical wet pit (sump) applications,cavitation can be a problem which is best addressed atthe design stage.

Cavitation Considerations at the Design/Application Stage. Cavitation can be generally avoided by providingthe NPSHR of the pump at the maximum flow requirement and water temperature anticipated. The followinganalysis should be performed during the pump selection process:

1. Determine the maximum flow requirement under all possible operating condition and select the pump which canhandle the maximum flow requirement within the published performance curves.

2. Calculate NPSHA for the application and compare with the maximum NPSHR of the selected pump at maximumflow point established in item 1 above. NPSHA must be greater than NPSHR to prevent cavitation. Refer toSection 2B for various NPSHA calculation scenarios.

3. The submersible pump intake must always be submerged for proper operation. In some cases, the minimumsubmergence requirement is dictated by the NPSHR needs of the pump. The minimum submergence should beno less than 1.5 feet (or as specified by the manufacture) at the lowest possible pumping level at maximum flow.Should the NPSHR needs of the pump require positive submergence pressure to satisfy, addition submergenceshould be added to 1.5 feet minimum requirement.


Section 2

Section 2D Pumping System Application Considerations 2-39

Factors which may create/contribute to conditions favorable for cavitation, which are often overlooked (or are notreasonable to consider) at the design stage are; entrained (free) gas, sudden drops in discharge head (counterpressure) that significantly increase pump flow (ie. piping failure/discharge to waste), insufficient submergence(dewatering/ improper low level shut-off point), etc.

Cavitation Prevention in Existing Installations. Once the pump is in service, cavitation problems as a result ofinsufficient NPSHR can be difficult to correct. Pump NPSH difficulties can be reduced through one or more of thefollowing corrective measures.

1. Evaluate system head condition, NPSH available and consider reducing pump capacity by throttling.2. Change pump impellers to obtain low NPSH design and/or utilize priming inducer.3. Replace pump end assembly with different model capable of operating within the system NPSHA4. Increase pump size and/or reduce speed for more favorable pump NPSHR characteristics, while still meeting

application requirements.

Vortexing. Vortexing is a term frequently used to describe flow patterns which result in formation of vortices,causing loud rumbling noises. A vortex is a whirlpool caused by a combination of factors such as sump design,inlet velocity, direction of flow, submergence and position of intake. Air entering the pump through these vorticesare responsible for noise and vibration, but not cavitation.

Vortexing is rare in submersible pump application; however, when it does occur, it is generally a result of impropersubmergence. When it is not possible to increase submergence or decrease flow and vortexing is suspected, theproblem can generally be corrected with a motor shroud which tend to break-up vortices. In sump application, it isalways advisable to use a motor shroud for cooling. Sump application with no motor shroud are most susceptible tovortexing, as it is often difficult to achieve adequate submergence on account of the motor length.

Other methods used to reduce vortexing include; good sump design practices, lowering sump inlet velocity,locating pump near pit walls and away from inlets, and installing intake accessories which tend to break-up vorticessuch as a splitter plate and/or intake strainer.

Submergence. Submergence should not be confused with NPSH, as it is a term used to relate liquid level to theintake setting level. In the case of a conventional submersible pumps some submergence, in addition to the NPSHR,is necessary to maintain prime and prevent vortex formation on the liquid supply surface.

Minimum Submergence. The minimum amount of submergence required will depend to some extent on the designconfiguration of the pumps intake and its ability to break-up/prevent vortices, impeller specific speed andorientation within the wet well. Minimum submergence requirements are commonly provided by the pumpmanufacture and should be used for design purposes when required. In the absence of this information,submergence requirements can be approximated using one of the following rules of thumb which fits theapplication.

1. Can/De-Watering applications. 1.5’ (18”) above the pumps intake plus 1’ additional submergence for each 500gpm of flow (ie. minimum submergence at 1000 gpm should be no less than 3.5’).

2. Sump application. 1.5’ (18”) above the pumps intake plus 1’ additional submergence for each 1 fps in approachchannel/piping inlet velocity.

3. Submergence vs Intake Velocity. A graphical solution to minimum submergence can be obtained using Figure 2-27, and knowing the impeller eye diameter (cross sectional area) and maximum flow rate. Figure 2-27 can alsobe used to calculate submergence requirements over intake and suction piping.

Regardless of the submergence requirement, the entire pump length should be submerged up to the dischargeoutlet at start-up. Otherwise, water lubricated pump bearing are subjected to potentially destructive dry-run untilsuch time as the impellers are able to pick-up sufficient water to provide the required lubrication.


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Figure 2-27: Submergence Requirements vs. Intake Velocity

0 2 4 6 8 10 12 14 16

INTAKE VELOCITY (fps)

16

14

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6

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H-S

UB

ME

RG

EN

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.)

The submergence values approximated using “rules of thumb” are in addition to any positive NPSH submergenceneeds of the pump at maximum design flow.

Good design practices call for submergence values in the range of 40’- 20’ for high capacity water wells, with 40’ orgreater being preferred. The absolute minimum submergence value should be no less than 10’ below the maximumwell drawdown level, although some installations may require more submergence to satisfy NPSH requirements.Submergence for domestic water well applications (Q < 25 gpm) should be maintained at a minimum of 3’ abovethe pump intake.

Maximum Submergence. Excessive submergence is a factor which can potentially affect submersible motoroperation. It is rarely a consideration with respect to the pump end of the submersible unit. Typical maximumsubmergence values range from 200 psi (450’) to 500 psi (1100’) for hermetically sealed motors, where it is notpossible to equalize internal pressure with the surrounding external pressure. Motor submergence issues arediscussed in Section 4B.

Velocity = Q (.321)/A or= Q (.4085)/D2

Where: A = Area (sq. in.)D = diameter (in.)Q = Flow (gpm)

H (Min.)

D

H (Min.)

D

H (Min.)

D2 (Min.) DD

1.5D

3D(Min.)

NOTE:

When submergence data is notprovided for a particular pump, itcan be estimated on impeller eyediameter (cross section area) andmaximum design flow rates.

The submergence is in addition tothe positive NPSH needs of thepump.

Entrained GasMost liquids carry small amounts of air or other gases completely dissolved in the liquid. This small amount ofentrained free gas has little effect on fluid flow or pumping requirements. In some cases; significant amounts of freegas are introduced intentionally, accidentally or naturally. Common modes of gas introduction in groundwater are.

1. Intentionally - as part of the disinfection process, such as ozination 2. Accidentally - as a result of vortices, air leaks, and cascading water.3. Naturally - as a result of formation gas.

Entrained gas is typically not a problem until it exceeds approximately 1-2% of the total pumped volume of thefluid. The primary effect of entrained gas is to change the specific gravity (sg) of the liquid. When water with a sgof 1.0 is mixed with 5% air by volume, the resulting water/air mixture will have a approximate sg = 0.95. Thepresence of entrained gas is usually noted by; (1) noise, (2) frequent and speratic pressure surges, and (3)deterioration of H - Q performance and efficiency. In extreme cases, entrained gas can prevent pumping as a resultof “gas locking”.

Entrained gas and cavitation are similar in effect, but are not directly related. In the entrained gas case, free gasbubbles are present in the fluid prior to entering the pump intake (suction). Water vapor formation associated with


Section 2

Section 2D Pumping System Application Considerations

cavitation are formed within the pump as a result of insufficient NPSH. Entrained gas can aggravate cavitation bycontributing to a lighter fluid column reducing NPSHA. Vortices associated with the lack of adequate submergencecan introduce significant amounts of entrained air. The entrained gas that flows through the pump is compressed,but rarely are the internal pressures within the pump high enough to collapse free bubbles of air of formation gas,creating cavitation.

The two most common entrained gas problems encountered in water well applications involving submersiblepumps are cascading water (falling water) and formation gas. The issue of vortices are discussed under the generalheading of cavitation.

Cascading water. Falling water occurs as a result of the pumping water level dropping below the top of the wellscreen. Cascading water is a difficult problem, in that blocking the offending section of screen, often significantlyreduces well capacity. The amount of entrained air can be mitigated by installing the pump near the bottom of thewell and utilizing a motor shroud.

Effect of entrained air. The buildup of entrained air specifically affects the performance of centrifugal pumps asshown in Figure 2-28. Centrifugal force throws heavier liquid outward from the impeller eye. The lighter air remainsbehind and will gradually build into a bubble as big as the impeller inlet (“eye”) area, which chokes off the intakeflow. This is called “air locking” and is functionally the same as gas locking as described above. Most centrifugalpumps can operate (at reduced performance) with a air content up to 6% by volume; however, a air lock conditioncan result at significantly lower level if the pump is operated near shut-off.

Formation gas. The presence offormation gas is detrimental in thatsurging and/or gas locking contribute tocyclic loading and potential dry runfailure. Always use underload and/or noflow protection when large amounts ofentrained formation gas is anticipated.The amount of entrained formation gascan often be mitigated through the use ofa inverted shroud which forces thepumped fluid to make a 180 degreechange of direction prior to entering thepump intake, provided the pump isinstalled above the screen. The invertedshroud should be extended as highabove the intake as possible to force theliberation of as much of the free gas aspossible before entering the pump intake.

When sufficient room exists within the well screen, good results can be achieve by using a cooling shroud andplacing the pump near the bottom of the well. The shroud forces the fluid to make a 180 degree change indirection and has the added benefit of increased submergence pressure; which may help keep a larger volume ofthe otherwise free gas in solution by maintaing a pressure greater than the “bubble point pressure” of the formationgas. The top portion of the shroud should be equipped with a small vent to allow for the escape of free gas thatmay accumulate in the top over time. The oil industry commonly utilizes specialized submersible pumps which canbe equipped with centrifugal gas separators to improve H-Q performance and reduce the occurrence of gas locking.

Summary of Entrained Gas Mitigation Measures. Pumps subjected to entrained gas as a result of; formation gascascading water, and/or vortices can be mitigated through one or more of the following measures where applicable.

1. The use of a gas shrouds, which forces the fluid make a 180 degree change in direction.

2. Increase submergence to reduce potential vortexes and/or to increase submergence pressure on entrained gas inorder to keep it in solution (ie. below the gas bubble point pressure).

2-41

Figure 2-28: Air Entrainment and H-Q Performance

250 500 750 1000

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CAPACITY (GPM)

TOTA

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3. The use of high specific speed impellers (greater axial flow less opportunity to trap gas) where possible

4. Reduce pump speed through the use of a Variable Frequency Drive (VFD). In some applications, a VFD can beused to speed-up the pump to force accumulated gas through the pump when low motor current is sensed.

5. Install air release valve (s) at high and low points in the system, specifically at well head discharge elbow.

6. Drill gas relief holes through impellers and diffusers to eliminate gas locking.

Entrained Solids (Sandy Water)The characteristics of liquids are influenced by the amount and type of solids entrained in the liquids. A simpleexample is silty river water. In this case, the solids in the water have a negligible effect on normal pumpingcharacteristics. In many cases the nature and concentration of materials entrained in the fluid can significantlyimpact pump performance.

The most common problem encountered for pumping equipment used in the water supply industry is sand. Sand isoften introduced in to the system as a result of pumping ground water from a well that has not been completelydeveloped, was improperly designed/constructed or has failed. Sand pumpage as a result of incompleteddevelopment will eventually subside as the well is pumped, assuming the well is pumped within its design limits.When sand pumping is a result of well failure or improper construction/design, the following corrective measuresmay be applicable.

• Reduce pumping rate (Q), so as to decrease well screen velocity to 0.5 ft./sec. (fps) per foot or less:

Q (max) @ 0.5 fps = .022 (ID) x (% screen open area/100) x Ls

where: ID = Screen inside diameter (in.)Ls = Screen length (ft.)Q = flow (gpm)

• Install down hole sand separator or sand shield. The use of a sand shield should extend below the screen. Bothmay require periodic pump pulling to facilitate sand removal.

• Install above ground sand separator, trap and/or filter to eliminate sand entry into distribution system.

• Install well liner or patch casing break where applicable. A well liner will significantly reduce well yield.

• Construct new properly designed well and abandon sand pumping well

The National Ground Water Association (NGWA) has developed the following application guide lines based on sandcontent from well water.

1. 1 mg/l in water used for food and beverage processing

2. 5 mg/l in water for private residences, institutions and industries

3. 10 mg/l in water for sprinkler irrigation, industrial evaporative cooling and other applications where a moderatecontent of solids is not particularly harmful.

4. 15 mg/l in water for flood irrigation

When the sand content exceeds 15 mg/l, for a prolong period of time, corrective measures should be taken toreduce the amount of sand being pumped. Premature well failure and reduced pump life will likely occur if nothingis done. A typical sand specification for a new water well is: “sand content not to exceed 5 mg/l, 15 minutes afterthe start of pumping”. A properly designed and constructed well should easily maintain the sand content levelsubstantially below 1 mg/l.



Section 2


Grundfos stainless steel submersible pumps are designed to operate satisfactory at sand (entrained solids) contentlevels up to 50 mg/l. At the 50 mg/l level, the minimum design life is 25,000 duty hours. The excellentabrasion/wear resistance of the Grundfos submersible pump makes it an ideal product for water well service andselected special applications where abrasive particles up to 50 mg/l might be present.

Water HammerWater Hammer is an excess pressure or reaction due to changes in velocity of water (incompressible fluid) flowingthrough a pipe line. It occurs most frequently and with greatest intensity in pumping lines where the pulsation orsudden stoppage of the pump or the rapid closing of a valve in the pipe line causes a significant monentaryincreased pressure shock wave in the pipe. The kinetic energy (momentum) of the flowing water is converted intoa dynamic pressure (shock) wave. A complete analysis of water hammer and the calculation of pressure surgemagnitude is outside the scope of this discussion. The maximum magnitude of the pressure wave in steel and castiron pipe can be estimated using Figure 2-29.

The pressure surge increase is independent of system working pressure. The pressure increase will be exactly thesame whether the normal operating pressure in the pipe line is 100 psi or 1000 psi. Low working pressure (lowhead) systems, such as gravity concrete irrigation systems are particularly susceptible to damage from waterhammer. The piping materials used have relatively low collapse and burst pressure ratings, relative to water hammershock pressures commonly experienced. Water hammer is often accompanied by a sound comparable to that heardwhen a pipe is struck by a hammer, hence the name. Intensity of sound is no indicator of the magnitude of thewater hammer shock wave pressure, as water hammer is not always accompanied by autable sound.

The pressure (shock) wave generated by sudden flow stoppage, travel at approximately the acoustic velocity ofsound in water (4865 fps @ 68°F). The accustic velocity of water is approximately four times that of sound in air(1160 fps @ 100°F).

Figure 2-29: Maximum Shock Pressure caused by Water Hammer (based on instantaneous valve closure or pump stoppage - no mitigation)

5000

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Steel PipeCast Iron Pipe

, PIPE SIZE PRESSURE, PSIdt

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LO

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Y O

F P

RE

SS

UR

E W

AV

E –

FT.

/SE

C.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

VELOCITY OF WATER – FT./SEC.

Inside Diam., InchesWall Thickness, Inches

=de p = Shock Pressure, Lbs./Sq. In.

Solving Water Hammer (general). Water hammer is generally not a problem in water system application providedthe following issues are addressed:

1. Velocities within pipelines can be maintained within generally accepted design ranges (3 fps - nominal forhorizontal piping / 5 fps - nominal for vertical piping).

2. Pressure rating of piping should be no less than the maximum anticipated working pressure of the system. Afactor of safety of 2 to 4 times the working pressure rating for pressurized systems is advisable.

3. Valve closure is not instantaneous. The larger the piping and greater the fluid velocity, the slower the valveclosure should be.

4. Surge energy can be attenuated through a buffer such as a; surge/expansion tank (diaphragm tank) or stand pipe(elevated gravity storage tank). System storage in public water systems is normally adequate to absorb surgeenergy.

5. Thrust blocking of piping is recommended and often required to maintain line integrity at all significant changesof direction, as a result of fluid momentum and water hammer.

6. Vacuum and pressure reliefs are placed at all high and low points of inflection within the piping system. Vacuumbreak devices should be placed at all piping locations where the momentum of the fluid is likely to continue,pulling a vacuum, when fluid is stopped abruptly. Pressure relief valves should be used in addition to surgeenergy devices, where the possibility of exceeding the established pressure failure limit (burst pressure, workingpressure, pressure rating, etc.) of the system exists.

Solving Water Hammer (pumps). The solutions for general water hammer also apply to pumps. In submersiblepumping applications, where the vertical distance to the water is significant, it is recommended that one or more ofthe following measures be incorporated into the design to reduce the water hammer potential.

1. Install surge/ expansion (diaphragm) tank in the immediate vicinity of discharge elbow, downstream of anysurface valving. In general, a 200 gallon (50 l) surge tank is recommended for each 225 gpm (50 m /hr.). Thetank precharge pressure should be 70 % of the actual system operating pressure. A hydropneumatic tank canprovide a similar degree of surge protection, provided no check valve exists between the tank and pumps.

When the submersible pump is supplied without in-line check valve (s) or the check valve has been modified todrain slowly. A air release/vacuum break valve should be installed in lieu of a surge tank, in the same location.The air release/vacuum break valve will prevent significant amounts of air from being forced into the system andbreak the vacuum that would otherwise form within the column (riser) piping. Refer to Section 1E forair/vacuum release valve sizing.

2. Soft start and stop via exstended ramp times, through the use of a variable frequency drive (VFD) or soft starter.A surge absorption device may be required in conjunction with a soft start if the ramp times can not be adjustedto prevent detrimental water hammer.

3. Hydraulicly or motor operated surface discharge valving can be used to control water hammer within the system.Frequently, valve control at the well discharge head simply transfers the pressure surge to the pump assemblyand / or the discharge header assembly. In such cases, the downhole and above ground components must bedesigned to withstand the surge stresses. Valve sequencing and control must be coordinated to insureeffectiveness. Control of water hammer with valving is typically done in two ways; (1) the pump is throttled atstart-up and slowly released into the system or (2) the pump is started discharging to waste and slowly closed inon the system.


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Section 2

Section 2D Pumping System Application Considerations

Downhole Check ValvesDownhole submersible check valves are typically used to hold system pressure when the pump stops, or to preventpumping equipment damage and/or prevent system operating problems as a result of; (1) well surging due to rapidcolumn drain, (2) pump start during backspin, (3) upthrust and (4) water hammer. The three most common no-check or faulty check valve problems are expanded on as follows:

1. Backspin - with no check valve or if the check valve fails, the water in the drop pipe and the water in thesystem can flow back down the column pipe when the motor stops. This can cause the pump to rotate in areverse direction. If the motor is started while this is happening, a heavy strain may be placed across the pump-motor shaft assembly. It can also cause excessive thrust bearing wear because the motor is not turning fastenough to ensure an adequate film of water in the thrust bearing.

2. Upthrust - with no check valve, or with a leaking check valve, the unit starts each time under zero headconditions. With most pumps, this causes an uplifting or upthrust on the impellers-shaft assembly in the pump.This upward movement carries across the pump-motor coupling and creates an upthrust condition in the motor.Repeated upthrust at each start can cause premature wear and failure of either or both the pump and the motor.

3. Water Hammer - If the lowest check valve is more than 30 feet above the standing water level or the lowercheck valve leaks and the check valve above holds, a partial vacuum is created in the discharge/ column piping.On the next pump start, water moving at very high velocity fills the void and strikes the closed check valve andthe stationary water in the pipe above it, causing a hydraulic shock. This shock can split pipes, break joints anddamage the pump and/or motor.

Swing type check valves should never be used with submersible pumps. When the pump stops, there is a suddenreversal of flow before the swing check closes, causing a sudden change in the velocity of the water. Spring loadedcheck valves should be used as they are designed to close quickly as the water flow stops and before it begins tomove in the reverse direction. There is little or no velocity of flow when the spring loaded valve closes and nohydraulic shock or water hammer is produced by the closing of the valve.

In general, column check valves are recommended for pump settings in excess of 450 feet. Some submersiblemotor manufactures recommend check valves for all applications, regardless of setting depth. Most small pumpsand some larger units have check valves built into the top of the pump. In pumps which do not have a built-incheck valve, a external check valve should be placed between 25 and 75 feet above the discharge, or are requiredto maintain positive submergence over the check valve under maximum drawdown conditions. Pump settings inexcess of 750 feet, should incorporate two check valves. When two check valves are used, the distance between thefirst/lower check valve and the surface discharge plate should be unequal. Unequal distances are essential toprevent harmonic valve hammer. The upper check valve should be located approximately 3/5 of the distancebetween the first valve and surface plate.

In cases where it is desirable to completely drain the column pipe, a check valve should not be used or it shouldbe modified to slowly allow column drainage. When no check valve is used, at time delay relay (backspin timer)should be incorporated into the control scheme to prevent start-up on backspin, as well as a method forintroducing air into the column pipe to prevent vacuum formation. When system pressure is present and must bemaintained, a surface check valve is required. A vacuum/ air relief value should be placed on the downstream sideof the surface check and on the upstream side of the pump or modified/ drainable downhole check valve. Whenonly partial column pipe drainage is required, for such purposes as air charging hydrophneumatic tank, a surfacecheck valve in conjunction with a air relief/drain valve located on the upper most column joint is adequate.

Typical check valve friction loss values are provided in Table 7-14.

Drain valves. Brass plug drain valves are available for small diameter column pipe. The brass plug is ruptured fromthe surface via heavy bar attached to a wireline. Drain valves are sometimes use to prevent the pulling of awet/heavy pumping string. Drain valves are typically installed one joint above the check valve.

2-45


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CorrosionGeneral. Corrosion is broadly defined as the destructive attack of a metal by chemical or electrochemical reactionwith its environments. The five (5) principal types of corrosion associated with pumping equipment used forgroundwater supply (natural water) applications are; galvanic, uniform, erosion, intergranular (crevice) and pitting.The rate of corrosion is influenced by many external factors. Several of the more critical factors are temperature,velocity, acidity (pH), dissolved gases, and entrained solids (abrasives).

Fortunately, in applications involving the pumping of potable natural waters, corrosive conditions are rare. Whenthey are encountered, corrosion can lead to a rapid reduction in service life, if not accounted for in the materials ofconstruction. Refer to Table 2-8 for a specific listing of environmental factors which indicate or tend to aggravatecorrosion.

Erosion (Corrosion and Abrasion Working Together). A pumps performance can be destroyed by corrosion orabrasion acting alone; however, the greatest difficulties are those where both are present. The destructive attack ofmaterial by both corrosion and abrasion acting together is referred to as erosion. All metals gain their protectionagainst corrosive agents through the formation of a thin skin of oxide film (passive corrosive condition). If this skinis wiped clean (active corrosive condition), the metal will recorrode forming a new skin. If abrasives (typically sand)are found in the corrosive fluid, it is possible for these to cause this wiping action. This will occur whenever thepumped fluid abrasive content is harder than the skin corrosion (or protective coating when used). Soft abrasivescan be present in large quantities without causing excessive wear. The greater the hard abrasive content, the greaterthe rate of corrosion. This condition is further aggravated by the velocity within the pump. By slowing the pumpspeed or oversizing the pump for the design conditions, the internal velocity is lowered. This will reduce theabrasive wear.

Large amounts or abrasive particles can destroy elastomer (rubber)/soft metal seals and bearings in a short period oftime. Increased bearing tolerances created by abrasive wear can create shaft stability problems within thesubmersible pump and damage the motor seal. The failure of bearings and seals to work properly, will impedepump performance and reduce service life.

In the application of submersible pumping equipment to natural water containing erosive contaminants, it is alwaysnecessary to consider the economic aspects first. The questions that need to be addressed are:

a) Should equipment of standard materials be used which will have a short operating life expectancy under theprevailing corrosive water condition and, therefore, a high frequency replacement? Or

b) Should equipment, using special materials be used in order to obtain a longer life cycle and thus increase thedependability of the equipment?

The general rule of thumb is to first select material which will withstand corrosion and from there, select thematerial that best resist abrasion. If the sand content is greater than 50 ppm (mg/l) and the pump is operated on aregular basis, it is likely that pump failure will occur as a result of abrasion long before corrosion is a factor. In sucha case, standard construction would be warranted.

Material Loss. The material loss caused by corrosion, abrasion or erosion can be quantified based on the depth ofattack as shown in Table 2-7 below:

Table 2-7: Evaluation of Corrosion & Wear Severity

Loss of Material

Depth of Attack inches per year

Insignificant 0 to 0.002

Moderate 0.002 to 0.02

Severe 0.02 to 0.05

Extreme 0.05 or more


Section 2


The material losses associated with an all bronze (BRZ) pump under erosive conditions, will be half that of a entirelycast iron (CI) product. Although a BRZ pump will have approximately double the life of an all CI pump, it may notbe suitable for certain applications as the deteriation of common bronze can liberate lead into the pumped fluid.

In general, stainless steel SS offers the best alternative as a cost effective corrosion resistant material in an aggressivewater environment. It has approximately ten (10) and five (5) times the erosion resistance of CI and BRZ pumpsrespectively. SS is strong, highly inert and relatively resistant to corrosion. Plastic composites can provide greaterchemical resistance than SS, but they generally do not have the strength characteristics required for deep well/highcapacity pumping applications.

SS is not always the best material for every application. The presence of certain chemicals in natural waters can resultin stress corrosion and hydrogen embrittlement. These factors can be mitigated by selecting the proper SS alloy.

Forms of Corrosion. Corrosion of pumps and associated equipment is one of the most important factors in deepwell pump failures. Several of the most common forms of corrosive attack encountered are described below.

• Galvanic corrosion occurs when a metal or alloy is electrically coupled to another in the same electrolyte. Theextent of accelerated corrosion resulting from galvanic coupling is affected by the potential difference betweenthe two metals or alloys, the environmental properties, the polarization behavior of the metal or alloys and thegeometric relationship of the two. The corrosion potential (galvanic series) presented in Figure 2-30 and Table 2-9 helps predict the corrosion resistance of various metals commonly used in the pump industry.

• Oxygen concentration cells develop at the water-to-air interface between oxygenated areas and areas deprived ofoxygen with the resultant corrosion occurring on the areas with less oxygen. Typically this form of corrosion willoccur on column (riser) pipe between the static and pumping water level.

• Carbon dioxide (CO2) corrosion takes place at the high pressure points in the pump bowl. Bubbles form in watercontaining CO2 gas at a high solution potential, upon rapid increase in pressure created by the pump. The waterfilm on the surface of each bubble is excessively acidic due to the formation of carbonic acid and is the cause ofthe corrosion damage.

• Cavitation is a mechanical corrosion process caused by collapsing bubbles in a flowing liquid. It is often inducedby a change in flow direction or reduction in the cross sectional area of a flow passage causing a decrease influid pressure and gas bubble (vapor) formation. An increase in pressure at a nearby location will violentlycollapse the bubble, causing mechanical damage to the metal surface.

• Corrosion to which well and pump components may be subject are stray currents due to foreign DC sources,corrosion cells resulting from temperature gradients, differential corrosion cells resulting from variations in soilconditions or cement coatings on the exterior of well casing.

Each of the above listed forms of corrosion can occur as a result of one or more of the corrosion modes previouslymentioned (galvanic, erosion, etc.). In the absence of abrasives in corrosive water, the second most prominentcorrosion accelarant is temperature. For every 25°F (15°C) increase in temperature, the corrosion rate isapproximately double.

In addition to the common forms of corrosion specified above for water well duty; there are other aggressive waterapplications where corrosion should be anticipated. These applications include mines, geothermal, pits and seawater.

Sea Water Corrosion. One of the most difficult corrosive fluids to handle and understand is sea water. This isbecause of several variables which can alter the effects of this fluid upon different metals being employed. The firstconsideration is temperature. All corrosive fluids are more active as the temperature is elevated. Therefore, wherecast iron might be used successfully at 32 degrees F (0°C), the story changes at 90 degrees F (32°C). Otherchemicals in sea water can cause difficulty if their presence is not known. Around oil docks, drilling, etc., hydrogensulfides (H2S) is often present. Even in small quantities, H S can cause the pumped fluid to be much morecorrosive. The other consideration is the quantity of sand present. Off shore installations are subject to tides andwave action. This can cause a difficult system to analyze. The electrolytic action of dissimilar metals in the presenceof the sea water must also be taken into account.


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Defending Against Corrosion. The best corrosion defense is operational experience for the specific application.For new applications, where historical corrosion performance is not available, the following mitigating/protectivetechniques should be considered in the initial submersible pump system design when an aggressive waterenvironment is anticipated. These techniques are; materials of construction (metallurgy), cathodic protection(sacrificial anode) and protective coatings.

Materials of Construction. There are a variety of materials available for use in aggressive water applications,the most prominent being stainless steel (SS). Grundfos uses three principal alloys of austenitic (chromium -nickel) SS in the construction of its entire line of submersible pump products. The various alloy employed andthe recommended application are described as follows:

• AISI 304 Stainless steel (W.nr. 1.4301). 304 SS is used as the standard material of construction for potablewater applications. It is generally applicable for applications in the mild to moderate corrosive gradingcategory. It can also be used in the presence of chlorides up to 1000 ppm, provided water temperature isless than 50°F (10°C).

• AISI 316 Stainless Steel (W.nr. 1.4401- “N-type”). 316 SS is more resistant to water with a moderate contentof salt (ie. brakish water). It is generally applications in the moderate to severe corrosive grading category.The chloride content and temperature associated with brackish water applications should not exceed 5000ppm and 50 F (10°C) respectively.

• AISI 904L Stainless Steel (W. nr. 1.4539 - “R-type”). 904L is generally used for warm seawater applications. Itshould be used anytime chlorides are in the range of 5000 - 20,000 ppm and fluid temperatures areanticipated to exceed 50°F.

The relationship between chloride content and temperature is illustrated in Figure 2-30. These diagrams arebased on a pH range of 7-8 and pumps which are utilized (run) on a regular basis.

Bearings and Seals. Grundfos utilizes elatomers, principally nitril butyl rubber (NBR), for bearing and seals inits standard groundwater products. NBR provides excellent wear and corrosion resistance in a majority ofaggressive natural water environments. NBR is acceptable for most applications in the mild to severe category,provided the presence of man-made pollutants/contaminants (solvents, hydrocarbons, pesticides, etc.) are lessthan 1.0 ppm. The existence of man-made pollutants in groundwater has virtually no impact on stainless steelmetallurgy and other elastomers (FPM and TFE) can be provided for special environmental applications.

Figure 2-30: Corrosion Diagram for Stainless Steel (Chlorides vs. Temperature)

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68

50

320 4000 8000 12000 16000 20000

CHLORIDE (PPM)

Corrosion Diagram

TE

MP

ER

AT

UR

E (

°F)

SPR 904LSPN 316SP 304

212

194

176

158

140

122

104

86

68

50

320 400 800 1200 1600 2000

CHLORIDE (PPM)

Corrosion Diagram

TE

MP

ER

AT

UR

E (

°F)

SPR 904LSPN 316SP 304

Brackish and Sea Water Quality Fresh Water Quality


Section 2


Cathodic Protection. The sacrificial anode technique is the only cathodic protection method that can beemployed practically down hole. A zinc anode equal to 20% of the net submerged pipe weight is usuallysufficient for long term protection in aggressive water. The amount of zinc required can be reduced by the netweight of the pump and motor if constructed/cladded in stainless steel. The zinc must be attached in a waythat will promote good electrical conductivity between the steel to be protected and the anode. Refer toFigure 2-31 for a typical submersible pump configuration utilizing a zinc anodes.

Figure 2-31: Fitting of Zinc Anodes

Protective Coatings. Protective coatings commonly employed down hole for metallic materials; include but arenot limited to galvanizing, epoxy, coal tar and tape. Coatings are most often applied to column pipe and relatedaccessories such as check valves. Care should be used to insure coatings are applied completely and uniformly,as an imperfection in the coated surface will actually accelerate the corrosive process at the point ofimperfection. It is a good practice to coat the exterior of both the most and least noble materials in the pumpstring when practical. Always remove wrench marks and touch-up coating blemishes before installation.

Column (Riser/Drop) Pipe Corrosion. The choice of column pipe for high capacity pump applications dependson several factors, with resistance to corrosion being one of the key issues. All three of the mitigation measurespreviously discussed are applicable to the protection of column pipe. The most common protective measures arediscussed below:

In mild to moderate corrosive conditions, standard mill coated (black) steel pipe should be adequate. A commonlyfollowed field practice is to replace or rearrange the most severely corroded sections of pipe in the submerged internalbetween the static water level and setting depth any time the pump is pulled. Where a stainless steel pump is joinedto mild steel column pipe; it is a good practice to generously apply thread joint compound at the coupling point,before and after make-up to insure the exposed threads are coated. Tape (4” wide 10 mil recommended) should beapplied to the column pipe immediately above the connection point (1/3 overlap) to a minimum of three (3) feetabove the joint. This simple protective measure has proven successful in decoupling the galvanic corrosion cell byproviding limited insulation and separation between the two (2) dissimilar metals. A dielectric (plastic) coupling ornipple can be used to eliminate direct galvanic contact, provided strength and space requirements can be met.

When severely corrosive conditions are anticipated, the use of stainless steel column pipe should be considered inthe submergence interval at a minimum. In the absence of an electrolyte, galvanic corrosion is generally not anissue when the change over from stainless to mild steel is made above the static water level. Where the applicationcalls for infrequent pump use, it is recommended to allow the column pipe to drain to eliminate unnecessarycorrosive contact. Draining can be accomplished by removing the built-in check valve or drilling a small .25” (6mm) hole through the check valve floating cone.

In addition to stainless steel pipe, plastic tubulars and certain corrosive resistant hose type products are available foruse as column pipe for low capacity/low temperature applications. As was the case for the use of plastic in theconstruction of large - high capacity pumps, the strength of plastic products limit there application in the largesubmersible industry.


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Table 2-8: Corrosivity/Incrustating Indicators for Natural Water

Corrosivity Grading Typ. Values for

Water Characteristics Mild Moderate Severe High Quality GW

Corrosive Indicators/Major FactorsChloride (ppm) 0-250 250-500 > 500 0-150Free Carbon Dioxide (ppm) 0-35 35-50 > 50 2-22Hydrogen sulfide (ppm) Nil < 1 > 1 0-0.5Conductivity (umhos-cm) 0-500 500-2000 > 2000 100-1600*Temperature (°F) < 80 80 - 90 > 90 40-70Dissolved Oxygen (ppm) <.5 .5-2 > 2 0-0.5pH 6-7.5 < 6 < 6 6.5-8.5Total Dissolved Solids (ppm) 50-200 200-1000 > 1000 0-700* Suspended Solids - sand (ppm) 0-15 15-50 > 50 ppm < 15

Corrosive Indicators/Minor FactorsNitrates (ppm) 0-.5 .5-45 > 45 0-5Nitrites (ppm) 0-.003 > .003 > .003 0Ammonia (ppm) 0 -.05 > .05 >.05 0Turbitity (NTU) 0-1 1-5 > 5 .1-.4Color (CU) – > 15 > 15 < 2Odor (TON) – > 3 > 3 None**Carbonate Alkalinity (ppm) 5 -125 < 5 < 5 70-200**Carbonate Hardness (ppm) 30-100 < 30 < 5 85

Incrustation Indicators/Major Factors pH – > 7.5 > 8.5 –**Carbonate Alkalinity (ppm) – > 125 > 300 –**Carbonate Hardness (ppm) – > 100 > 300 –Iron (ppm) 0-2 > 2 > 2 .1-.3Manganesse (ppm) 0.2 .2-1 > 1 < .05Calcium (ppm) 0-10 10-10,000 > 10,000 0-100

Incrustation Indicators/Minor FactorsMagnesium (ppm) 0-5 > 5 > 5 0-5***Carbonates (ppm) 0-10 > 10 > 10 < 5Suphates (ppm) 0-100 100-350 > 350 0-50

Notes1. Combinations of the above conditions classified as severe will enhance the corrosive effect. The presence of chlorides (Cl),

carbon dioxide (CO ), hydrogen sulfide (H S) and dissolved oxygen (DO) in the severe category will have an immediatecorrosive affect on ferrus material and temperatures above 80°F.

2. The above classification/grading table is presented as a guideline for evaluating materials of construction for groundwaterpumping equipment and related appurtenances. Many of the factors are interrelated and should be evaluated on the wholebefore making a selection. The expected/design service life and its initial cost should be carefully considered in theevaluation process.

3. Classification of water by individual constituents and properties for corrosivity has no relationship to acceptability of thewater for potable purposes.

4. Steel, cast iron and bronze construction is generally suitable for applications in the mild grading category. The Grundfosstandard construction is AISI 304 SS (stainless steel) and is applicable for service in the mild to moderate grading category,provided water temperature is less than 50°F (10°C) and chlorides are less than 1000 ppm. AISI 316 SS construction shouldbe considered for applications where one or more severe indicator parameters are present, and for brackish water dutywhere chlorides range from 1000 - 5000 ppm and water temperature is less than 50°F. AISI 904L SS construction isrecommended for extremely corrosive conditions such as warm seawater (chlorides 5,000 - 20,000 ppm/ > 50°F).

5. Applicability of the elastomers components used in standard groundwater products (normally NBR) should be evaluatedfor use under severe conditions.

6. Incrustation refers to plugging and scaling phenomena commonly associated with GW.

* Suspended solids (such as abrasive sand) and elevated temperature do not constitute corrosive condition on there own.Abrasive particles and elevated temperature can significantly accelerate pump failure in the presence of aggressive water. ** Alkalinity & Hardness measured in terms of CaCO content. *** Carbonates measured in terms of CO content.


Section 2


Table 2-10: Material Requirement Minimums based on pH

PH Range Material of Construction

0 - 4 Stainless Steel (SS)

4 - 6 All Bronze (BRZ)

6 - 8 Cast Iron Bronze Fit (CIBF)

8 - 10 All Cast Iron (CI)

10 - 14 Stainless Steel (SS)

Table 2-9: Galvanic Corrosion Resistance of Commonly Used Metals in the Pump Industry (Galvanic Series)

Notes:1. This series is built upon actual experience with corrosion

and laboratory measurement. Metals grouped together haveno strong tendency to produce galvanic corrosion on eachother; connecting two metals distant on the list from eachother tends to corrode the one higher in the list. Voltagefigures are not given because these vary with every newcorrosive condition. Relative positions of metals change inmany cases but it is unusual for changes to occur across thespaces left blank. The chromium irons and chromium-nickel-irons change position as indicated depending on oxidizingconditions, acidity, and chloride in solution. The series as itstands is correct for many common dilute water solutionssuch as sea water, weak acids and alkalies.

2. Electrical path is from the anode to the cathode Copper isthe cathode with respect to iron in the presence of anelectrolyte.

3. Corrosion electrochemical phenomina is always a directcurrent (DC) process.

Corroded end (anodic or least noble)

Magnesium/Zinc/Aluminum

Iron/Steel/Cast Iron

Tin solder/ Tin/Lead

Nickel - Iron (NI-Resist)

Aluminum Bronze

Brass/Bronze/Copper

Copper-Nickel alloy

Nickel-Aluminum Bronze

Nickel - Copper alloy (Monel)

Silver Solder

Stainless Steel 400/304/316

Stainless Steel 904L

Nickel - Chrome alloy

Silver/Gold/Platinum

Protected end (cathodic or most noble)

Note: 1. 400 series SS = (Chromium) Stainless Steel2. AISI 304 SS = 18-8 (Chromium-Nickel) Stainless Steel3. AISI 316 SS = 18-8-3 (Chromium-Nickel-Molybdenum) Stainless Steel

* AISI = denotes American Iron and Steel Institute /SS = Stainless Steel

pH. The acidity or alkalinity of a solution is expressed by its pH value. A neutral solution such as water has a pHvalue of 7.0. Decreasing pH values from 7.0 to 0.0 indicate increasing acidity and pH values from 7.0 to 14.0indicate increasing alkalinity. Each unit in the pH scale represents a multiple of 10 (ie. PH = 3 is 10 more acidicthan a pH = 4). Since the pH value denotes the acidity or alkalinity of a liquid it gives some indication of thematerials required in constructing a pump to handle the liquid. The pH value alone; however, is not conclusive.Many other factors must be considered. Table 2-10 can be used as a guide for determining pumping system materialrequirements.


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Testing General. Pump tests can be conducted in the factory or the field. Factory testing of standard large submersiblepumps (LSP) are normally conducted to insure actual performance meets published design parameters withinallowable tolerances or when specific pump performance is required. Field tests are useful to indicate wear and/orchanging conditions from test to test and for determination of overall plant efficiency. The test parameters ofprimary interest are capacity/flow, head and power input.

ASME standards define “pump efficiency (PE)” as the energy difference in the water between the discharge andsuction intake (WHp-water Hp) divided by power input at the pump shaft (BHp-brake Hp). “Overall efficiency(OE)” takes into account losses in both the pump and motor, and is equal to the WHp divided by the power inputat the motor terminals (EHp-electrical Hp). “Overall plant efficiency (OPE)” sometimes referred to as field or wire towater efficiency, takes into account all submersible installation losses ( pump, motor, power cable, friction losses,etc.) and can only be determined in the field. OPE is equal to the WHp divided by the input power measured fromthe surface to the motor (IHp-input Hp).

Pump Efficiency Overall Efficiency Overall Plant Efficiency

Factory Testing. From a pump manufacture’s standpoint, “pump efficiency” - sometimes referred to as laboratoryor bowl efficiency, is the most important indictor of the degree of perfection of its product. Pump efficiencydetermines the relative “overall efficiency” of the whole unit. Factory performance tests are normally conducted inaccordance with one of the following standards:

1. Hydraulic Institute. 2. ISO 2548 Annex B.(a.) At rated head: Q + 10% @ published capacity (a.) Q +/- 8%

(b.) At rated capacity: H + 5% @ published capacity (<500’) (b.) H +/- 6%H + 3% @ published capacity (>500’)

(c.) BHp +/- 8%(c.) At rated head or capacity: BHp + 10%

Note: (1) The minimum hydrostatic test pressure should be no less than 125% of the shut-off head or 150% of themaximum anticipated operating pressure.

(2) Industry practices commonly allow for motor loading into the service factor, assuming ambient fluid temperature does not exceed 80°F.

The ISO standard has become the preferred Head-Capacity (H-Q) standard in the LSP industry as it allows for atolerance about nominal performance and is more reflective of the average performance to be expected from astandard product. The Hydraulic Institute standard is more conservative, as there is no minus tolerance allowed.

Basis of Comparison. In comparing pump performance, care should be used to see that efficiencies published bydifferent manufactures are calculated on the same basis. Typical factors which contribute to variations in thepresentation of published/submittal data are;

(1) Inlet and discharge losses: Some manufactures incorporate a built in check valve and/or have several differenttypes of inlets (interconnectors) to allow for connection to various motor sizes. These losses are sometimes notincluded as they have little impact on overall performance except in low head applications. Such losses aresometimes accounted for by an efficiency/performance reduction table based on the number of stages used.

(2) Test speed: The motor used in the testing process can have a appreciable affect on pump H-Q performance as aresult of the variability in performance between manufactures and sizes. Larger submersible motors will have less slipthan smaller motors and will operate at a higher speed for the same Hp. A pump tested with a smaller motor of theproper horsepower rating will produce lower H-Q performance than the same pump tested with a larger motor.Typical 2-pole submersible motor full load speeds, based on standard motor diameters are; 4”-6” (3450 rpm), 8” (3525rpm) and 10” (3540 rpm). Performance at speeds other than the test speed can be recalculated using the affinity laws.

PE = WHp/BHp OE = WHp/EHp OPE = WHp/IHp


Section 2


Test types. Most manufactures have the capacity to perform the following tests; performance test (non-witnessed),performance test (witnessed) and hydrostatic test. Performance test can be further quantified as certified or non-certified. A certified performance test requires the use of a calibrated motor with specific - known electrical,efficiency and speed characteristics. Each manufacture has specific guide lines and criteria, associated with testingperformed within the factory. A factory performance test should be ordered whenever precise H-Q and efficiencydata for a specific unit is required.

Test data. Factory test data is generally extremely accurate as instrumentation and piping can be configured for highaccuracy in a controlled environment. Test data is typically presented in a graphical format with a tabulation ofspecific individual test points. Records of all relevant pump information such as s/n, type and size are normallyprovided on the test forms, as well as the driver involved in the test. The information to be recorded at each testpoint must include; (a.) capacity/flow in gpm - Q, (b.) head in ft.- H, (c.) pump speed in rpm and (e.) electricaldata - P (volts, amps and kW input). Minimum recommended measurement precision is Q +/- 2.5%, H +/- 2.5% andP (power) +/- 2%.

Test controls. Test data must be collected within the specified operating conditions for the pump being tested. NPSHrequirements must be met, which is generally assured with a minimum submergence of 5 feet over the suctionintake for LSP’s. Motor voltage should be within 5% of the nameplate rating during the test and there should be nogreater than 2% imbalance between phases. Current (amp) readings should be balanced within 5% of the averageinput current valve to the motor. Flow metering should be performed in a straight pipe section at a point 10 pipediameters downstream and 2 pipe diameters upstream of the nearest obstruction. Water temperature should bemaintained within the range of 50 - 80°F, with 68 - 70°F considered ideal.

Field Testing. Cost factors and space limitations rarely allow for ideal test conditions. In order to obtain accuratefield performance test data, it is necessary to design the complete pump installation with future field testing inmind. Provision must be built into for the system to allow for the use of suitable calibrated testing instruments. Thereliability of a field test is a function of the accuracy of the instruments used, the proper use of instrumentation andthe skill of the test personnel. Typical field test instrumentation accuracies are listed in Table 2-13.

Many electrical utilities offer no cost “pump test” for non-residential power consumers. Table 2-11 list a typical OPErating scale used by electrical utilities. Table 2-12 lists various formulas and useful information used in makingcalculations associated with field pump tests.

Submersible Pump Field Test Guidelines. A field test provides an indication of the pump performance underfield conditions. In addition the OPE and wear indicator uses, a field test qualitatively indicates; (1) pump (bowl)operation, (2) column pipe and discharge friction loss, (3) cable losses, (4) air and sand content of water, (5)mechanical vibration and noise, (6) well characteristics and (7) driver and control operation.

a. Flow Measurement - The rate of flow may be measured by; (1) thin plate orifice, (2) venturi and flow nozzle, (3)volume or weight for a time duration of not less than one minute and liquid level of not less than 2’, (4) pitottube and (5) propeller meter

Note: Flow approximations listed in Tables 7-16 to 7-18 can be used in the absence of more accurate means .

b. Head Measurement - The head below the selected datum line, or static and pumping water levels may bemeasured by; (1) chalked steel tape, (2) air-line and (3) electric line.

The head above selected datum line may be measured by;

1. Bourdon tube pressure gauge, calibrated. Reading converted to feet plus or minus distance from datum tocenterline of gauge plus velocity head. Velocity head is normally neglected in field measurements as it is onlya small component of the total head (TH) in well applications. A velocity head of 10 fps accounts for less than0.1’ of an additional head.

2. Manometer, when head above datum is sufficiently low. The manometer fluid should produce a deflection ofat least five inches.

c. Power Measurement - Various methods for measuring electrical input power are presented in the next sectionunder the heading of “Power Consumption of Electric Motors”.


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d. Pump Speed Measurement - The speed measurement in a submersible pump application is best accomplishedthrough the use of a reed type tachometer. The reed tachometer senses vibration in piping set-up by motor andpump rotating parts.

e. Test Procedure - Test data recorded should include; (1) pump size, make, number of stages, type and serialnumber, (2) motor size, make, type and serial number, (3) description of instruments, constants and multipliersfor data recorded, (4) water temperature at pump discharge and submergence, (5) quality of water, (6) staticwater level in ft., (7) pumping water level in ft., (8) reference datum in ft., (9) pressure head in ft., (10) capacityin gpm, (11) current each line in amperes, (12) voltage each line in volts, (13) pump speed and (14) meter discconstant, rpm and speed time, seconds.

Simultaneous and instantaneous readings of all instruments should be avoided. Continuous observation ofinstruments for at least one minute prior to recording data is recommended.

Example 2-4: Typical Utility Pump Test Analysis:

Given: (1) Motor nameplate Hp rating: 100 Hp, (2) Em = .85 (from mfg. data)

Measured Data: (1) SWL = 200’, (2) PWL = 240’, (3) AGH = 35 psi (35 x 2.31= 80.9’), (4) Q = 700 gpm, (5)Meter readings: Kh = 4.8, M = 10, R (disk revs.) = 20, t (time for 20 revs.) = 50.2 sec.

Analysis (using formulas from Table 2-12)1. Static Water Level (SWL): 200’ 2. Pumping Water Level (PWL): 240’ 3. Discharge Pressure (Pdsh): 35 psi 4. Flow Rate (Q): 700 gpm5. Above Ground Head (AGH): 80.9’

• AGH = 35 x 2.31 = 80.96. Total Head (TH): 320.9’

• TH = AGH + PWL = 80.9 + 240 = 320.9 *7. Drawdown (DD): 40’

• DD = PWL - SWL = 240’ - 200’ = 40’8. Well Yield (SC): 17.5 gpm/ ft. of DD

• SC (specific capacity / well yield) = Q/ DD = 700/ 40 = 17.59. Volume pumped in 24 hrs.: 3.09 ac. - ft. or 1008 kgal.

• Af/ 24 hrs. = Q/226.3 = 700/ 226.3 = 3.09• 1000 gal./ 24 hrs. = Q/ 1.44 = 700 x 1.44 = 1008

10. Kilowatt Input to Motor (kWI): 68.8 kW• kWI = (R x Kh X M x 3.6)/t = 20 x 4.8 x 10 x 3.6/ 50.2 = 68.6

11. Horsepower Input to Motor (IHp): 92.2 Hp• IHp = kWI/ .746 = 68.8/.746 = 92.2

12. Motor Load (%): 78.4%• Motor Load = (IHp x Em/ Rated Hp) = 92.2 x .85/ 100 = .784

13. Water “hydraulic” Horsepower (WHp): 56.7 Hp• WHp = TH x Q / 3960 = 320.9 x 700/ 3960 = 56.7

14. Kilowatt - hours per Volume pumped: 533.6 kWh - Af or 1.64 kW - kgal.• kWh/ Af = (4051.5 x IHp)/ gpm = 4051.5 x 92.2/ 700 = 533.6• kWh/ 1000 gal. = 12.44 x IHp/ gpm = 12.44 x 92.2/ 700 = 1.64

15. Overall Plant Efficiency (OPE): 61.5%• OPE = WHp/ IHp = 56.7/ 92.2 = .615

Note: (1) Based on Table 2-11; a OPE of 61.5% is considered “fair” for the operating point analyzed.(2) Multiple test points will generally be analyzed (typically three points).* Pipe and fitting losses are not included in OPE testing


Section 2


Table 2-11: Description of Pump Condition based on Overall Plant Efficiency (OPE) in %

Motor Hp Low Fair Good Excellent

3 - 7 1/2 44.0 or less 44 - 49.9 50 - 54.9 55 or above

10 46.0 or less 46 - 52.9 53 - 57.9 58 or above

15 47.0 or less 48 - 53.9 54 - 59.9 60 or above

20 - 25 47.9 or less 50 - 56.9 57 - 60.9 61 or above

30 - 50 52.0 or less 52.1 - 58.9 59 - 61.9 62 or above

60 - 75 55.9 or less 56 - 60.9 61 - 65.9 66 or above

100 57.2 or less 57.3 - 62.9 63 - 66.9 67 or above

150 58.0 or less 58.1 - 63.4 63.5 - 68.9 69 or above

200 59.0 or less 59.1 - 63.8 63.9 - 69.4 69.5 or above

250 59.0 or less 59.1 - 63.8 63.9 - 69.4 69.5 or above

300 59.9 or less 60 - 64.0 64.1 - 69.9 70 or above

Table 2-12: Typical Pump Test Calculation Formulas and Useful Data

(1) Q in gpm - Typically measured by Velocity - Area method (manometer), Direct method (meter) or Time -Volume (container and stop watch)

(2) kWI = R x Kh x M x 3.6)/ t = (I x E x pf x C)/ 1000 ** See “Power Consumption and Cost” for explanation of metering terminology

(3) Motor Load (%) = (IHp x Em/ Rated Hp) x 100 **** Rated Hp, normally taken as motor nameplate Hp value

(4) TH = H = PWL + AGH ****** Pipe and fitting friction losses are not compensated for in OPE testing

(5) IHp = kWI/ .746 (6) kWI = IHp x .746

(7) OPE = WHp/ IHp (8) WHp = (TH x gpm)/ 3960

(9) SC = Q/DD (10) DD = PWl - SWL

(11) kWh/ Af = (4051.5 x IHp) /Q (12) Af/ 24 hrs. = Q/ 2263

(13) kWh/ kgal. = (12.44 x IHp)/ Q (14) kgal./24 hrs. = Q/ 1.44

Where; Q = flow (typ. in gpm), IHp = Input Horsepower (Hp), kWI = Kilowatt input (kW), Em = full loadmotor efficiency, TH = total head (ft.), PWL = Pumping (dynamic) Water Level (ft.), AGH = Above Ground Head(typ. measured in psi and converted to ft.), WHp = Water Horsepower (Hp), OPE = Overall Plant Efficiency,SWL = Static Water Level (ft.), DD = Drawdown (ft.), Af = volume in acre - feet (ac. - ft.), kWh = Energy(kilowatt-hrs.), kgal. = 1000 gal., SC = Specific Capacity or well yield (gpm/ ft.)

Note: 1. Typ. Motor efficiencies (Em)****Hp Range Surface Em (%) Submersible Em (%)

1 - 3 78 - 82 (80) 70 - 74 (72)5 - 15 83 - 87 (85) 75 - 81 (78)

20 - 200 88 - 92 (90) 82 - 88 (85)

**** Use manufacture published efficiency data in calculations when available

2. Common Pump Test Conversions (water - sg = 1.0)1 psi (gauge pressure) = 2.31 ft. of head (2.31’/ psi) 1 gal. = 8.34 lbs. (ie. 8.34 lbs./ gal.)1 Hp = .746 kW (ie. .746 kW/ Hp) 1 Af = 32,585 gal. (ie. 32,585 gal./ac-ft.)1 ac. = 43,560 sq. ft. 1 gal. = 231 cu. in. 1 cu. ft. = 7.48 gal. 1 in. of Hg = 1.134 ft.


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Table 2-13: Limits of Accuracy of Pump - Test Measuring Devices in Field Use

Measured Measuring Accuracy Measuring AccuracyParameter Devices Limit (%) Devices Limit (%)

Capacity Venturi Meter ± 3/4 Piston ± 1/4(flow) Nozzle ± 1 Volume or weight - tank ± 1

Pitot tube ± 1 1/2 Propeller meter ± 4Orifice ± 1 1/4 Magnetic meter ± 2Disc ± 2

Head Electric sounding line ± 1/4 Bourdon gauge - 5” dial.Air line ± 1/2 1/4 - 1/2 full scale ± 1Liquid manometer ± 3/4 1/2 -3/4 full scale ± 3/4(3-5 in. deflections) over 3/4 scale ± 1/2Liquid manometer ± 1/2 Note: A 5” dial is the minimum(over 5-in. deflections) recommended size for a test gauge

Power Watt-hour meter and stopwatch ± 1 1/2 Test type precision watt meterInput* Portable recording watt meter ± 1 1/2 1/4 - 1/2 scale ± 3/4

Clamp-on ammeter ± 4 1/2 -3/4 scale ± 1/2over 3/4 scale ± 1/4

Speed Revolution counter and stopwatch ± 1 1/4 Stroboscope ± 1 1/2Hand-held tachometer ± 1 1/4 Auto. counter and stopwatch ± 1/2Reed type tachometer xxx

Voltage* Test meter - 1/4-1/2 scale ± 1 Test meter - 3/4-full scale ± 1/2Test meter - 1/2-3/4 scale ± 3/4 Rectifier voltmeter ± 5

* True rms metering devices are required for accurate measurement of electrical properties where the pump iscontrolled through a non-linear device such as a Variable Frequency Drive (VFD)

Power Consumption and CostPower Consumption of Electric Motors. The two most common methods used to check power consumption are“direct measurement” using electrical instrumentation and the “desk constant method” using the utility power meter. Thefirst of these requires the use of an ammeter and voltmeter or power meter. The second requires only a stopwatch.

Direct Measurement Method. Utilizing electrical instrumentation to obtain current and voltage measurements, thefollowing formulas can be used to calculate motor power consumption.

or, where;

kWI = Kilowatts (electrical input power) I = amperes (meter reading) E = volts (meter reading)IHp = Horsepower (electrical input power) pf = Power Factor (per mtr. - mfg.) .80 - .85 typ.)C = 1 for single phase current / 2 for two phase, four wire control / 1.73 for three phase current

Disk Constant Method. Utilizing the utility watt-hour meter and the exact time for a given number of revolutions of themeter disc measured with a stopwatch, and the following formulas can be used to calculate motor power consumption.

or, where;

kWI = Kilowatt Input (kW) IHp = Input horsepower (Hp)R = Total revolutions of watt-hour meter disc. t = Time for total revolution of disc in seconds.kh = Disc constant, representing watt-hours per revolution. This factor is found on the meter nameplate or painted

on the disc.M = Transformer ratio multiplier, product of the meter current transformer (CT) and potential transformer (PT) ratio.M = 1 when neither a CT or PT is used in power metering.

kWI = (I x E x pf x C) /1000 IHp = (I x E x pf X C) /746

kWI = (3.6 x kh x M x R) /t IHp = (4.83 x kh x M x R) /t


Section 2


Cost of Pumping using an Electric Motor. The term “Efficiency” as used in pumping would be of no practicalvalue if it could not be reduced to terms of actual pumping costs expressed in dollars. When the efficiency of thepump and motor is known, proportionate cost of power can be predetermined on a basis common to all pumps,regardless of size or capacity. By using units of capacity and head, comparisons can be made in pumps havingdifferent capacities.

Power cost of pumping varies inversely with overall plant efficiency (OPE). Thus, power cost per gallon for eachfoot head on a pump of 30% OPE, is double that of a pump of 60% OPE. (Assuming power rate the same in bothcases). In order to pump one gallon of water in one minute (1 gpm) against one foot head at 100% OPE, requires.000189 kilowatts. Pumping 1000 gpm per foot head at 100% OPE requires .189 kilowatts (kW).

The following formulas can be used for determining power requirements and associated cost when differingpumping parameters are known.

1. Cost per hour ($/hr.) of operation

where; kWI = kW input, PR = power rate ($/kWh), IHp = Input Hp,PE = Pump efficiency, Em = Motor efficiency, TH = Total head (ft.),Q = flow (gpm), Cost = $ (dollars)

2. Cost per 1000 gal ($/1000 gal.)

where; 1000 gal. = 1 kgal.

Note: Table 2-14 can be used to quickly estimate power consumption and cost of operation based on kW/1000gal. pumped, when the overall plant efficiencies (OPE’s) are known.

3. Cost per Acre - ft. ($/Af)

where; Af = acre - ft, PR = power rate ($/kWh)

Cost of Pumping using a Diesel Engine. The cost of operating a submersible pump powered by a diesel enginegenerator can be estimated as follows.

where; PE = pump efficiency Em = motor efficiency (engine)Eg = generator efficiency

Note: (1) Formula based on a fuel requirement of 0.065 gal. or diesel per Hp - hr.(2) Em and Eg can be assumed to be approximately the same in the absence of specific

generator efficiency information.

Cost of Pumping using a Gasoline Engine. The cost of operating a submersible pump powered by a gasolineengine generator can be estimated as follows:

Cost/hr. = kWI x PR Cost/hr. = IHp x .746 x PR Cost/hr. = Q x TH x .746 x PR3960 x PE x Em

Cost/hr. = .000189 x Q x TH x PROPE

Cost/kgal. = Cost/hr.1000

Cost/kgal. = 12.44 x IHp x PRQ

Cost/kgal. = .189 x PR x THPE x ME

Cost/kgal. = .00315 x PR x THOPE

Cost/kgal. = (kWh/kgal) x PR

Cost/Af = 1.032 x TH x PROPE

Cost/Af = 4051.5 x IHp x PRQ

Cost/Af = (kWh/Af) x PR

Cost/hr. of operation = gpm x TH x 0.065 x $ fuel/gal.3960 x PE x Em x Eg

Cost/hr. of operation = gpm x TH x 0.110 x $ fuel/gal.3960 x PE x Em x Eg


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Table 2-14: Comparative Costs of Pumping Water per ft. of Total Head (TH)

OPE kW / 1000 gal. OPE kW / 1000 gal. OPE kW / 1000 gal.

32 .00980 52 .00603 72 .00435

33 .00951 53 .00592 73 .00430

34 .00922 54 .00581 74 .00424

35 .00896 55 .00570. 75 .00418

36 .00871 56 00560 76 .00413

37 .00848 57 .00550 77 .00407

38 .00826 58 .00541 78 .00402

39 .00804 59 .00532 79 .00397

40 .00784 60 .00523 80 .00392

41 .00765 61 .00514 81 .00387

42 .00747 62 .00506 82 .00382

43 .00730 63 .00498 83 .00378

44 .00713 64 .00490 84 .00373

45 .00697 65 .00482 85 .00369

46 .00682 66 .00475 86 .00365

47 .00667 67 .00468 87 .00360

48 .00653 68 .00461 88 .00356

49 .00640 69 .00454 89 .00352

50 .00627 70 .00448 90 .00348

51 .00615 71 .00442 – –

* Overall plant efficiency (OPE) as indicated above is the input-output (wire to water) efficiency, including alllosses (pump, motor, power cable, friction losses, etc.) pumping 1000 gallons of clear cool water one foot (ft.)of total head (TH). In determining the kilowatts (kW) per 1000 gallons (gal.) pumped, it is only necessary tomultiply the factor corresponding to the OPE by the actual TH in feet.

Example 2-5: Assume an overall efficiency of 65% and a TH = 200’, PR = $0.07/ kWh

kW/kgal. = .00482 x 200 = .964 Cost/kgal. = .964 x 0.07 = $0.07

Energy - Efficiency and Cost. The costs associated with pumping is often many times higher than the original costof the pumping plant equipment (pump, motor and appurtenances). The “Simple Pay back Analysis” is the mostcommon method used to evaluate energy cost benefits associated with high equipment and/or plant efficiencies. Theanalysis can be applied to individual pumping equipment elements (ie. pump - PE, pump and motor - OE) or theoverall plant (pump, motor and losses - OPE). The 3 step simple payback analysis is illustrated in example 2-6 below.

Example 2-6: Simple Payback Analysis - OPE Efficiency Comparison

Required Information (from example 2-5): 1. Operating hrs./yr. = Op.-hrs. = 12 hrs/ day x 365 day/ yr. = 4380 hrs.2. OPE (low/initial) = OPEl = 61.5% (calculated in example 2-4)3. OPE (high/target) = OPEh = 67% (from Table 2-11)4. Cost/kWh = PR = $0.07/kWh 5. Input HP (IHp) @ OPE (low/initial) = IHpl = 92.2 Hp

(use design load Hp when comparing equipment efficencies)6. Load factor = 1.0 (fixed speed pump operation motor is generally assumed to be fully loaded) 7. Plant efficiency improvement cost (repairs) $5,200


Section 2


Step 1:

kW saved = 92.2 x .746 - x 1.0 = 8.94 kW

* Load is typically assumed to be 100% (1.0) for pumps operated at fixed speed and when a OPE comparison isbeing made. An average load correction % for plants operated under variable speed conditions should be used.When evaluating individual components such as motors, and the actual motor load % is known relative to thepumps BHp requirement, the actual motor load % should be used.

Step 2: where; $ saved = $ saved/ yr.

$ saved (yearly savings) = 8.94 x 4380 x 0.07 = $2741.48/ yr.

Step 3: where; eff. = efficiency

or,

Pay back in yrs. = Cost of Efficiency Improvements = $5,200 = 1.90 yrs.

Note: (1) The simple payback analysis does not take into account such factors as changing power costs, the timevale of money or deprecation

(2) All manufactures do not report efficiencies in the same manner. When making equipment comparisonsbetween manufactures, verify efficiencies were calculated on the same basis. OPE comparisons areindependent of the basis of calculations.

Energy Consumption Considerations. Pumping equipment efficiency, plant layout and system designs are crucialfor optimizing energy usage. Other factors, related to the cost of energy, which can significantly reduce the cost ofpumping are:

1. Off-peak pumping to storage to take advantage of off-peak power utility rates.

2. Utilization of the most efficient pumping plants in response to demand.

3. Split pumping demand between multiple pumps configured for cascade operation to maximize economy,reliability and efficiency.

4. Utilize variable frequency (speed) control in lieu of throttling valves where demand is highly variable andmultiple installations are impractical.

5. Maintain distribution pipeline velocities between 3 and 5 fps under peak flow conditions.

kW saved = IHp1 x .746 - x (Load factor) *[ ]1OPE1

1OPEh

1.615

1.67[ ]

Payback in yrs. = Cost of eff. Improvements (Repairs)$ saved

Payback in yrs. = Cost of high eff. equip. - cost of lower eff. equip.$ saved

$ saved = kW saved x (Op. - hrs.) x PR)

$ - Saved $2,741


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Section 2E Engineering Properties of Water2-60

Table 2-15: Altitude vs. Barometric Pressure and Boiling Point of Water

Altitude Barometer Reading Atm. Pressure Boiling Point

Feet (ft.) Meters (m) in.-Hg mm-Hg psia ft. Water °F

1000 304.8 31.0 788 15.2 35.2 213.8

500 152.4 30.5 775 15.0 34.6 212.9

0 0.0 29.9 760 14.7 33.9 212.0

500 152.4 29.4 747 14.4 33.3 211.1

1000 304.8 28.9 734 14.2 32.8 210.2

1500 457.2 28.3 719 13.9 32.1 209.3

2000 609.6 27.8 706 13.7 31.5 208.4

2500 762.0 27.3 694 13.4 31.0 207.4

3000 914.4 26.8 681 13.2 30.4 206.5

3500 1066.8 26.3 668 12.9 29.8 205.6

4000 1219.2 25.8 655 12.7 29.2 204.7

4500 1371.6 25.4 645 12.4 28.8 203.8

5000 1524.0 24.9 633 12.2 28.2 202.9

5500 1676.4 24.4 620 12.0 27.6 201.9

6000 1828.8 24.0 610 11.8 27.2 201.0

6500 1981.2 23.5 597 11.5 26.7 200.1

7000 2133.6 23.1 587 11.3 26.2 199.2

7500 2286.0 22.7 577 11.1 25.7 198.3

8000 2438.4 22.2 564 10.9 25.2 197.4

8500 2590.8 21.8 554 10.7 24.7 196.5

9000 2743.2 21.4 544 10.5 24.3 195.5

9500 2895.6 21.0 533 10.3 23.8 194.6

10000 3048.0 20.6 523 10.1 23.4 193.7

15000 4572.0 16.9 429 8.3 19.2 184.0

– –

– –

+ +

Table 2-16: Elevations for Various Municipalities (U.S. & Canada)

City Approx. Alt. (ft.) City Approx. Alt. (ft.) City Approx. Alt. (ft.)

Albuquerque 5200 Edmonton 2200 Phoenix 1100

Amarillo 3700 Fresno 380 Pittsburgh 800

Atlanta 1100 Ft. Worth 700 Regina 1900

Calgary 3440 Idaho Falls 4700 Roswell 3570

Cheyenne 6100 Kansas City 800 Reno 4500

Chicago 600 Minneapolis 900 Salt Lake City 4250

Cincinnati 550 Montreal 100 Spokane 1900

Cleveland 700 Nashville 500 Toronto 350

Denver 5270 Omaha 1000 Tulsa 800

Detroit 580 Ottawa 290 Winnipeg 760

2E ENGINEERING PROPERTIES OF WATER


Section 2

Section 2E Engineering Properties of Water 2-61

Table 2-17: Vacuum to Suction Lift Coversion (Inches of Mercury (Hg) to Feet of Water (H20))

Vacuum Suction Vacuum Suction Vacuum Suction Vacuum Suction

(in. - Hg) (ft. - H20) (in. - Hg) (ft. - H20) (in. - Hg) (ft. - H20) (in. - Hg) (ft. - H20)

8 9.07 16 18.14 24 27.22

1/4 0.28 8 1/4 9.35 16 1/4 18.42 24 1/4 27.50

1/2 0.56 8 1/2 9.64 16 1/2 18.71 24 1/2 27.78

3/4 0.85 8 3/4 9.92 16 3/4 18.99 24 3/4 28.07

1 1.13 9 10.21 17 19.28 25 28.35

1 1/4 1.41 9 1/4 10.49 17 1/4 19.56 25 1/4 28.63

1 1/2 1.70 9 1/2 10.77 17 1/2 19.84 25 1/2 28.91

1 3/4 1.98 9 3/4 11.06 17 3/4 20.13 25 3/4 29.20

2 2.27 10 11.34 18 20.41 26 29.48

2 1/4 2.55 10 1/4 11.62 18 1/4 20.70 26 1/4 29.76

2 1/2 2.84 10 1/2 11.90 18 1/2 20.98 26 1/2 30.05

2 3/4 3.12 10 3/4 12.19 18 3/4 21.27 26 3/4 30.33

3 3.41 11 12.47 19 21.55 27 30.62

3 1/4 3.69 11 1/4 12.75 19 1/4 21.83 27 1/4 30.90

3 1/2 3.98 11 1/2 13.04 19 1/2 22.11 27 1/2 31.19

3 3/4 4.26 11 3/4 13.32 19 3/4 22.40 27 3/4 31.47

4 4.54 12 13.61 20 22.68 28 31.75

4 1/4 4.82 12 1/4 13.89 20 1/4 22.96 28 1/4 32.03

4 1/2 5.11 12 1/2 14.18 20 1/2 23.24 28 1/2 32.32

4 3/4 5.38 12 3/4 14.46 20 3/4 23.53 28 3/4 32.60

5 5.67 13 14.74 21 23.81 29 32.89

5 1/4 5.95 13 1/4 15.02 21 1/4 24.09 29 1/4 33.17

5 1/2 6.23 131/2 15.31 21 1/2 24.38 29 1/2 33.46

5 3/4 6.52 13 3/4 15.59 21 3/4 24.66 29 3/4 33.74

6 6.80 14 15.88 22 24.95 30 33.90

6 1/4 7.08 14 1/4 16.16 22 1/4 25.23

6 1/2 7.37 14 1/2 16.45 22 1/2 25.51

6 3/4 7.65 14 3/4 16.73 22 3/4 25.80

7 7.94 15 17.01 23 26.08

7 1/4 8.22 15 1/4 17.29 23 1/4 26.36

7 1/2 8.50 15 1/2 17.57 23 1/2 26.65

7 3/4 8.97 15 3/4 17.86 23 3/4 26.93


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Table 2-18: Properties of Water from 32°F to 300°F(Vapor Pressure and Specific Gravity vs. Temperature)

Temp. Vapor Pressure Specific Temp. Vapor Pressure Specific

°F psia ft.-Hd Gravity °F psia ft.-Hd Gravity

32 .0885 .20 .9999 64 .2951 .68 .9987

33 .0922 .21 .9999 66 .3164 .73 .9985

34 .0960 .22 .9999 68 .3390 .79 .9982

35 .1000 .23 1.0000 70 .3631 .84 .9980

36 .1040 .24 1.0000 75 .4298 .99 .9974

37 .1082 .25 1.0000 80 .5069 1.17 .9966

38 .1126 .26 1.0000 85 .5959 1.39 .9959

39 .1171 .27 1.0000 90 .6982 1.62 .9950

40 .1217 .28 1.0000 95 .8153 1.89 .9941

41 .1265 .29 1.0000 100 .9490 2.21 .9931

42 .1315 .30 1.0000 110 1.275 2.98 .9906

43 .1367 .32 1.0000 120 1.692 3.96 .9888

44 .1420 .33 .9999 130 2.223 5.21 .9857

45 .1475 .34 .9999 140 2.889 6.79 .9833

46 .1532 .35 .9999 150 3.718 8.75 .9803

47 .1593 .37 .9999 160 4.741 11.20 .9773

48 .1653 .38 .9998 170 5.992 14.20 .9738

49 .1716 .40 .9998 180 7.510 17.90 .9702

50 .1781 .41 .9997 190 9.339 22.30 .9667

51 .1849 .43 .9997 200 11.530 27.70 .9632

52 .1918 .44 .9996 210 14.120 34.00 .9592

53 .1990 .46 .9996 220 17.190 42.00 .9952

54 .2064 .48 .9995 230 20.780 50.00 .9512

55 .2141 .50 .9994 240 24.970 61.00 .9467

56 .2220 .51 .9994 250 29.830 73.00 .9423

57 .2302 .53 .9993 260 35.430 87.00 .9373

58 .2386 .55 .9992 270 41.850 104.00 .9331

59 .2473 .57 .9991 280 49.200 123.00 .9281

60 .2563 .59 .9990 290 57.560 144.00 .9232

62 .2751 .64 .9989 300 67.010 168.00 .9180

Note: 1. The specific gravity (sg) is referenced to water at 39.2°F (4°C) at 1000’ , which is the point of maximumdensity. A sg reference value between 39.2°F and 70°F makes no practical difference in pumpingproblems.

2. Calculated from data in ASME steam tables.3. Kinematic viscosity ranges from 33.0 (1.93 EE-5 ft /sec.) to 29.3 SSU’s (3.19 EE-6 ft /sec.) for the

temperature range of 32° to 212°F respectively. Viscosity variations can decrease or increase frictionlosses as much as 40% between the two temperature extremes.

4. The specific weight of water at 32°F is 62.42 lbs/ft. (8.34 lbs./gal.).


Section 2

Section 2E Engineering Properties of Water 2-63

Figure 2-32: Suction Lift Correction for Elevation

12

10

8

6

4

2

00 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

ELEVATION ABOVE SEA LEVEL IN FEET

CO

RR

EC

TIO

N IN

FE

ET

From Total Suction Lift atSea Level Subtract

Correction for Elevation

Figure 2-33: Suction Lift Correction for Water Temperature

30

25

20

15

10

5

040 60 80 100 120 140 160 180 200 220 240

TEMPERATURE OF WATER IN DEGREES FAHR.

CO

RR

EC

TIO

N IN

FE

ET

From Total Suction LiftSubtract Correction for

Water Temperature


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Section 3

Section 3A Electrical Fundamentals



SECTION 3: ELECTRICAL – POWER & MOTORS

3A ELECTRICAL FUNDAMENTALS

• Fundamental Properties of Electric Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2• AC Circuit Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2• Circuit Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3• Power Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3• AC Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5• Phase Converters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5• High Voltage Surge Arrestor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6

3B INDUCTION MOTORS

• Induction Motor Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7• Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9• Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11• AC Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12• Motor Output Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12• Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15• Three Phase Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17• Three Phase Unbalance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19• Single Phase Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21• Power Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21• Power Factor Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-22• Environmental Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-23• Insulation Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-25• Rules of Thumb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26

3C MOTOR STARTING

• Full Voltage Starting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27• Reduced Voltage Starting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27

3D GRUNDFOS CONTROLLERS

• CU3 Motor Controller & Protector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-33• CU3 Technical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-35• CU3 with R100 Remote Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-35• R100 Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-35• R100 Menu Structure Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-36• CU3 with SM100 Sensor Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-38• G100 Gateway Communications Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-38• G100 Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-40• G100 Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-41

3-1


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Section 3A Electrical Fundamentals3-2

3A ELECTRICAL FUNDAMENTALSThis section is not an attempt to present a course in electricity, and is intended as a review of the terms and basicformulas associated with submersible pumping applications. In the application of electrical driven submersiblepumps, we are principally concerned with alternating current (AC) as it relates to three phase (3ph) power and to alesser degree on single phase (1p) AC circuits. Direct current (DC) circuits are directly analogous to 1 ph AC circuitswhen reactance is accounted for.

Fundamental Properties of Electric CircuitsElectricity is basically electrons in motion. Electromotive forces cause free or loosely bound electrons to move alongor through a medium. Materials such as aluminum, copper, silver and gold allow electrons to move freely and arecalled conductors. Materials such as porcelain, glass, rubber, plastics, and oils resist electron movement and arecalled insulators.

Forces that move electrons are magnetic. Moving a conductive wire in a way that cuts across a magnetic fieldinduces a force or voltage in the wire. If there is a path for the electrons to follow, a flow will be established. The

strength of the electro-motive forces (emf) is defined involts and is analogues to pressure in a hydraulicsystem. The magnitude of electron flow is calledcurrent and is measured in amperes, which is analogusto fluid flow. The resistance to current flow isanalogous to the friction loss of water flowing througha pipe and is measured in ohms. Voltage, current,resistant and power are related to each other by Ohm’slaw. Ohm’s law in its most basic mathematical form isexpressed as: E = IR and P = EI; where E = voltage(V), I = current (A - amps), R = resistance (ohms) andP = power (W - watts). Figure 3-1 illustrates thevarious electrical values derived from ohms law.

AC Circuit BasicsAC circuits differ form DC circuits in that voltage andcurrent follow an alternating - sinusoidal waveform asshown in Figure 3-2. They build up from zero to amaximum in one direction then diminish to zero, buildup again to a maximum but in the opposite directionand again diminish to zero. One cycle is completed intwo alternations and 360 electrical degrees in a 60-Hertz system.

Figure 3-1: Ohm’s Law Electrical Fundamentals

Figure 3-2: AC Waveform Fundamental Characteristics

EpIp

delay, pf = cos (delay in degrees)

Voltage

CurrentErms

Irms

Time

+

–

0

0 90° 180° 270° 360° 1 cycle @ 60 Hz


Section 3


The magnitude of the voltage and current is expressed in terms of its root-mean-square (rms) or effective valve. Therms value is equal to the peak voltage or current level multiplied by 0.707 (ie. Erms = Ep x .707), and is equivalentin magnitude to DC voltage or current level of the same numeric value (ie. Erms = Edc). The frequency at whichone complete voltage or current cycle is completed, dictates the operating frequency of the circuit or system. In theUnited States, the standard operating frequency is 60 Hz (60 cycles/second).

Circuit ImpedenceMost AC circuits contain coils, transformers and other electrical apparatus that produce magnetic effects. Thesemagnetic effects from such devices react upon the current, by retarding (delaying) its flow, causing it to lead or lagbehind the voltage as diagrammatically illustrated in Figure 3-2.

The magnetic reaction is called reactance, which has two possible components - inductance and capacitance.Inductance is the most prevalent magnetic influence in AC power circuits and systems. Inductive reactance causescurrent to lag voltage. The reverse of inductance is “capacitance”, and its effect on current is to cause it to leadvoltage. Capacitance reactance tends to counteract circuit inductance, improving power factor (pf). Circuitcapacitance is introduced into a circuit through the use of capacitors.

In an AC circuit there is three factors which affect current flow; resistance, inductance and capacitance. Thecombined affect of any two or all three of these effects is referred to as impedence, as they tend to impede currentflow. Capacitance and inductance create the reactive (Xc and XL) component of impedence (Z) and is referred toreactance, while resistance represents the real (non-magnetic) component of Z.

Impedence is measured in ohms and is mathematically expressed as: Z = R2 + (XL - Xc)2 ; as is a function offrequency (f - Hz), inductance (L - Henrys) and capacitance (C - farads). In an AC circuit, Ohm’s law is moreapplicably stated as: E = IZ.

Power FactorCircuit/system reactance, either capacitive or inductive, is responsible for the delay between current/power involtage as shown in Figure 3-2. The delay/offset is measured in electrical degrees, and is commonly referred to asthe phase angle between the real/active current or power component and the total apparent/actual current orpower. The power factor (pf) concept is illustrated in Figure 3-3.

3-3

Figure 3-3: Power Factor (pf) - Vector Analysis Presentation

E

(Im)Reactive/MagneticCurrent

Line/Actual/ApparentCurrent (IL)

Real/Active/Phase Current (Ip)

L° L°

Real/Actual PowerP = 1.73 EIL cosL (W of kW)

Reactive/MagneticPowerQ = 1.73 EIL sinL(VAR or kVAR)

S = 1.73 EIL (VA or kVA)

Apparent Power

pf = cos L, by Current Analysis pf = cos L, by Power Analysis (3 ph shown)

Where; P = Power (watts or kilowatts - W or kW), I = current (amps - A), E = Voltage (volts-V), Q = Reactive power (volt amperes reactive - VAR or kVAR), L = phase angle (degrees), S = Apparent power (volt-amperes - VA or kVA),

Note: The pf phase angle “L” between current and power phasers is the same; therefor, the pf calculated based on current or power data is the same value.


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3

The greater the phase angle; the lower/poorer the pf, the higher the circuit current and lower the real/usablepower. In a purely resistive circuit, or in a reactive circuit where capacitive and inductive reactance cancel eachother out, the pf = 1.0. Where there is a reactive component to impedence, the pf will be less than 1.0. A inductiveAC circuit has a lagging (inductive) pf, which will be less than one. A capacitive circuit has a leading (capacitive)pf, which will also be less than one.

At a unity pf (pf = 1.0), the voltage and current reach their respective maximum values simultaneously. In most ACsystem a slightly inductive condition exists, where voltage reaches its maximum value in a give direction before thecurrent attains its maximum value, then the current is said to be lagging. Consequently the pf is lagging and is aresult of the inductive characteristics of such apparatus as transformers, induction motors, etc. The actual currentdrawn by inductive apparatus have two components, (1) reactive and (2) real.

(1) The reactive current component can be defined as the magnetizing or lagging current. It is the current whichmust overcome the choking effect produced by the inductive characteristics of the apparatus. The reactive currentcomponent is zero when the voltage has reached its maximum level, and is said to be 90° out of phase with thevoltage.

(2) The real current component, can be defined as useful components and it is in phase with the voltage. The realcurrent and the voltage reach maximum values simultaneously.

The actual line current is the vector sum of the reactive and real currents, and is illustrated in Figure 3-3. It is thiscurrent that is registered with a ammeter. The subject of pf, as it applies directly to motors and pf improvement, arediscussed in Section 3B.


Table 3-1: Fundamental Electrical Conversion Formulas

Direct Current Alternating Current (AC)

Required (DC) 1-phase 3-phase*

IE

1000

kW

(pf)

1.73 IE

1000

kW

(pf)

kVA =

IE (pf)

1000

kVA (pf) 1.73 IE (pf)

1000

kVA (pf)kW = IE

1000

IE (eff) (pf)

746

.746 (kW) 1.73 IE (eff) (pf)

746

.746 (kW)Hp (output) = IE (eff)

746

IE (eff) (pf)

sec

1.73 IE (eff) (pf)

sec

Joules (J) = IE

sec

746 (Hp)

E (eff) (pf)

746 (Hp)

1.73 E (eff) (pf)

I (Hp known) = 746 (Hp)

E (eff)

1000 kW

E (pf)

1000 kW

1.73 E (pf)

I (kW known) = 1000 kW

E

1000 kVA

E (pf)

1000 kVA

1.73 E

I (kVA known) =

kW (1000)

IE

kW (1000)

IE (1.73)

pf =

kW

kVA

kW

kVA

* For 3-phase systems E is measured line to line and I is phase current.Where; E = Voltage, I = amperes, kW = kilo-watts, Hp = horsepower, eff = motor efficiency, pf = power factor (expressed as a decimal)


Section 3


AC PowerPower is defined as the rate of doing work. Electric power is typically measured in horsepower (Hp) or watts (W),one Hp equals 746 watts. One watt is a rather small unit of power; consequently, when speaking of power requiredby motors, the term kilowatt (kW) is used, one kW being a thousand watts. To obtain the power delivered to analternating - current motor, you cannot merely multiply effective (rms) amperes by effective (rms) volts. If the circuitcontains inductance, and motor circuits always contain it, the product of the effective current and effective voltagewill be greater than the real power. This “apparent power” is measured in volt amperes (VA) or more often in a unit1,000 times as large, the kilovolt-ampere (kVA).

The fundamental formulas for calculating electrical power and current flow are listed in Table 3-1.

Three phase (3ph) power is made-up of three separate single phase (1ph) waveforms as shown in Figure 3-4. Eachof the individual waveforms isgenerated at 120 electrical degreesapart from each other. The 1.73factor ( 3) in the 3 ph ACformulas in Table 3-1, accounts forthe additional two input phases.The power factor (pf) term presentin both the 1ph and 3 ph ACformulas, take into account themagnetic affects within the circuitsystem created by reactivecomponents such as; motors,transformers and capacitors.

Phase ConvertersA phase converters is a devices used to convert single-phase (1 ph) power to three-phase (3 ph) power, allowing 3ph motors to be used on a 1 ph power line. There are three basic types of phase converters; static (electro-mechanical), rotary and electronic - solid state.

Phase converters are typically used when the cost of 3 ph power line extension is cost prohibited, lack ofavailability of appropriate 1 ph motors, temporary 3 ph service is required until permanent - utility supplied 3 phpower is available, etc. Phase converters are normally rated in terms of kVA in lieu of horsepower.

In general, phase converters which employ electro-mechancial means; such as capacitors, winding taps or adjustablerelays. In these arrangements, a “manufactured” third leg voltage is created via a phase shift of a existing leg, whichcreates a voltage balance problem. Some phase converters may be well balanced at one point on the systemoperating curve, but change drastically with changes in load as water level and discharge pressure fluctuate. Otherconverters may be will balanced at varying loads, but their output may vary widely with fluctuations of input voltage.

Electronic Phase Converters. Commercial solid state phase converters can provide excellent performance underchanging load and input voltage levels. If a phase converter is necessary, a electronic - solid state model should beemployed. A variable frequency drive (VFD) can be used as a phase converter by derating the VFD unit byapproximately 65% it also can be used as a frequency converter from 50 to 60 Hz and provides a soft start.

The following guidelines should be used where phase converters are used in conjunction with submersible pumpinstallations.1. Limit pump loading to rated horsepower. Do not load into motor service factor.2. Maintain at least three feet per second motor cooling. Use a flow sleeve when necessary.3. Use time delay fuses or circuit breakers in pump panel. Standard fuses or circuit breakers do not provide

secondary motor protection.4. Verify suitability of control, starting and protective equipment for use with a phase converter. 5. Current unbalance must not exceed 10% under varying load conditions.

The motor and/or control manufacture should be consulted for specific recommendation whenever a phaseconverter is used.

3-5

Figure 3-4: Three Phase AC Waveform

PHASE 1

PHASE 2

PHASE 3

STA

RT

1/4

CY

CL

E

1/2

CY

CL

E

3/4

CY

CL

E

1 C

YC

LE

1-1/

4 C

YC

LE

1-1/

2 C

YC

LE

1-3/

4 C

YC

LE

2 C

YC

LE

+

0V

OLT

AG

E


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High Voltage Surge ArrestersA high voltage surge arrester should be used to protect the motor against lightning and switching surges. Lightningvoltage surges in power lines are caused when lightning strikes somewhere in the area. Switching surges are causedby the opening and closing of switches on the main high-voltage distribution power lines.

The correct voltage-rated surge arrester should be installed on the supply (line) side of the control box (Figures 3-5and 3-6). The arrester must be grounded in accordance with the National Electrical Code and local codes andregulations.


Figure 3-5: Single Phase Hookup Figure 3-6: Three-Phase Power Supply


Section 3

Section 3B Induction Motors 3-7

3B INDUCTION MOTORSInduction Motor OverviewElectric motors are devices which convert electric energy to kinetic energy, usually in the form of a rotating shaftwhich can be used to drive a fan, pump, compressor, etc. The most common type motor used in the pumpindustry, submersible motors included, is the squirrel cage - alternating current (AC) induction motor. A generalbreakdown of the various electric motor, types are illustrated in Figure 3-7. In a induction motor, the primarywinding (stator) is connected to the power source while the secondary winding (rotor) carries induced current.

Figure 3-7: Electric Motor Type Overview

ElectricMotors

DCMotors

SinglePhase

Synchronus

Induction

WoundRotor

SquirrelCage

Poly phase /Three phase

Induction

Synchronus

SquirrelCage

WoundRotor Design A

Design B **Design CDesign DDesign F

Split Phase *Capacitor Start *Perm. Split Cap.Cap Start-Cap Run.Split ph Start-Cap. RunShaded Pole

ACMotors

* Single phase submersible motors generally fall into these categories** Three phase submersible pump motor generally fall into the NEMA Design B category

Single-phase (1 ph) motors are commonly used up to 3 horsepower (Hp), occasionally larger. Three-phase (3 ph)motors are preferred in electrical design for 3/4-Hp motors and larger, since they are self-balancing on the 3ph service.

Motors come in various styles design types and efficiency ratings. The efficiency is typically related to the amountof iron and copper in the windings; the more iron for magnetic flux and copper for reduced resistance, generallythe more efficient the motor. The topic of efficiency is discussed in greater latter in this section.

Motors are typically selected to operate at or below the motor nameplate rating, although this is not always the casein the submersible motor industry where motors are often loaded into there service factors under nominal operatingconditions. Motors used in the U.S. typically have service factor of 1.15 or more, which represents the maximumcontinuos overload capability of the motor at rated conditions. Since motors are susceptible to failure when theyare operated above the rated temperature, care must be taken in motor selection for hot environments.

Principles of Operation. In a induction motor, the stator winding is distributed uniformly around the innercircumference of the stator. The current in the winding (s) are sinusoidally distributed, so as to produce a uniformrevolving field that drags the rotor around with it. Polyphase (three phase) motors have three separate statorwindings, one for each phase as shown in Figure 3-8. Single phase motors have a single winding, since there isonly one input phase, and require special provisions to start. Starting provisions are required to produce theneeded phase shift to begin rotation.

Current flow in the stator induces a magnetic field in the rotor, through the process of electro-magnetic induction.The rotor has no connections whatever to the line. As mentioned previously, the most common form of theinduction motor is the “squirrel cage” motor which takes its name from the fact that the rotor winding resembles thewheel of a squirrel cage. This type of induction motor consists of a stator and a squirrel cage rotor with bearings tosupport it. The stator, because it receives the power from the line, is often called the “primary”; the rotor is oftencalled the “secondary”.


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Section 3B Induction Motors3-8

Figure 3-8: Simplified Three-Phase AC Motor Schematic Diagram (6 pole illustration)

The squirrel-cage rotor winding consists of aluminum or copper bars mounted in core slots, connected together atthe ends with heavy end rings. A revolving field is set up by the currents in the stator (armature) of the inductionmotor. As this field revolves, it cuts the squirrel-cage rotor conductors inducing voltage. These voltages causecurrents to flow in the squirrel-cage circuit, through the bars under the north poles, into the end ring, back throughthe bars under the adjacent south poles, into the other end ring, completing the circuit back to the original barsunder the north poles.

The current flowing in the squirrel-cage rotor, down one group of bars and back in the adjacent group, makes aloop which establishes magnetic fields in the rotor core with north and south poles. This loop consists of one turn,but there are several conductors in parallel as the currents are heavy. These poles in the rotor are attracted to thealternating polarity poles of the revolving field set up by the currents in the stator winding. The rotor follows therotating magnetic field in the stator, in a manner similar to that in which the rotor field poles follow thestator/armature poles in a synchronous motor. The primary difference between the synchronous motor and theinduction motor is; the rotor of the induction motor does not rotate as fast as the rotating field in the stator. If thesquirrel cage rotor were to go as fast as the rotating field, the conductors in it would be standing still with respectto the rotating field rather than cutting across it. There would be no voltage induced in the rotor; therefore nocurrents would flow and no magnetic poles established in the rotor. This lack of attraction would prevent themotor from rotating.

Since the rotor in the induction motor must revolve at a slower speed than the revolving field in the stator to allowthe rotor conductors to cut the revolving magnetic field as it slips by, and induces the necessary currents in therotor windings. The motor can never go as fast as the revolving field but is always slipping back. This differencein speed is called the “slip”. The greater the load, the greater the slip will be, and the slower the motor will run,The topic of slip is discussed latter in this section.

The power factor and efficiency of an induction motor is generally lower at light loads than at full load. Inselecting a motor for a definite load, the size should be such as to operate at nearly full load for the mosteconomical operations; however, under adverse operating conditions it is sometimes best to operate below full loaddue to the operating conditions. The topic of power factor and efficiency is discussed in greater detail latter in thissection.

A electrical model of a induction motor, by equivalent circuit is illustrated in Figure 3-9.


Section 3


Figure 3-9: Induction Motor per Phase Equivalent Circuit

“per phase” model

The squirrel cage induction motor is one of the most efficient motors built. The speed of the squirrel cage motor isconstant under steady state load and voltage conditions; it is dependent on the number of poles configured withinthe stator input frequency.

Selection Information. The following minimal information is necessary in order to properly select a submersibleand/or surface induction motor for pumping applications:

• Source and Quality of power (utility supply, generator, high voltage variance)• Voltage and frequency of current (including probable variations in frequency and voltage).• Horsepower requirement of the driven pump.• The operating speed or speed range• Method of starting and control; soft start, part wind, Y-Delta, VFD, etc.• Type of motor enclosure; such as drip-proof, totally enclosed, weather protection, explosion proof, dust-ignition

proof or other enclosure - surface motors only.• The ambient or surrounding temperature.• Altitude of operation - surface motors only.• Special conditions of heat, moisture, dust, hazards or corrosive environment, etc. • Type of connection to driven machine (direct, belted, geared, etc.)• Transmitted bearing load to the motor (overhung load, thrust, etc.) • Well diameter - submersible motors only

VoltageVoltage (Definitions & Standards). The motor nameplate voltage is determined by the available power supplywhich must be known in order to properly select a motor for a given application. The nameplate voltage willnormally be less than the nominal distribution system voltage. The distribution voltage is the same as the supplytransformer voltage rating; the utilization (motor nameplate) voltage is set at a slightly lower level to allow for avoltage drop in the system between the transformer and the motor. Some specifications still call for 220, 440 or 550volt motors which were the long accepted standards. Modern distribution systems have transformers locatedadjacent to secondary unit substations or load centers, plantwide power factor correction, and shorter power lineruns. The result is a stiffer distribution system which delivers higher voltage at the motor. The motor nameplatevoltages listed in Table 3-2 provide the best match to distribution system voltages and meet current motor designpractices.

Dual Voltage Rated Motors. Polyphase and single-phase motors may be furnished as dual voltage ratings underthe following conditions:

1. Both voltages are standard for the particular rating as listed in Table 3-3.2. The two voltages are in a ratio of either 1:2 or 1: 3 (e.g. 230/460, 60 Hz; 2300/4000, 60 Hz; or 220/380, 50 Hz).3. Single-phase voltage ratios are 1:2 only.


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Table 3-2: Standard Motor Nameplate Voltages

Nominal Distribution Nominal DistributionSystem Voltage Motor Nameplate Voltage System Voltage Motor Nameplate Voltage

Three-phase 60 hertz < 125 Hp > 125 Hp Three-phase 50 hertz < 125 Hp > 125 Hp

208 200 - See Note 2 200 -240 230 - 220 -480 460 460 380 380600 575 575 415 4152400 2300 2300 440 4404160 4000 4000 550 5506900 6600 6600 30000 3000

Single-phase 60 hertz Single-phase 50 hertz

120 115 - See Note 2 110 -208 200 - 200 -240 230 - 220 -

Note: 1. The standards listed in the table were established based on the recommendations of the EdisonElectrical Institute and NEMA.

2. Distribution system voltages vary from country to country; therefore, motor nameplate voltage shouldbe selected for the country in which it will be operated.

Voltage & Frequency Variations. All motors are designed to operate successfully with limited voltage andfrequency variations. Voltage variation at rated frequency must be limited to 10% and frequency variations at ratedvoltage must be limited to 5%. The combined variation of voltage and frequency must be limited to the arithmeticsum of 10%. Variations are expressed as deviation from motor nameplate values, not necessarily system nominalvalues. The allowable 10% voltage variation is based upon the assumptions that horsepower will not exceednameplate rating and that motor temperature may increase.

A 230 volt motor operating at 207 volts (90% of rated) loses any service factor indicated on the nameplate, and willrun hotter than at rated voltage. The effect of voltage and frequency variation are described below.

Figure 3-10: Typical Effect of Voltage & Frequency Variation on Induction Motor Performance

A. Effect of Voltage Variation B. Effect of Frequency Variation


Section 3


Effects of Voltage Variation on Motor PerformanceA. An increase or decrease in voltage may result in increased heating at rated horsepower load. Under extended

operation this may accelerate insulation deterioration and shorten motor insulation life.B. An increase in voltage will usually result in a noticeable decrease in power factor. Conversely, a decrease in

voltage will result in an increase in power factor.C. Locked-rotor and breakdown torque will be proportional to the square of the voltage. Therefore, a decrease in

voltage will result in a decrease in available torque.D. An increase of 10% in voltage will result in a reduction of slip of approximately 17%. A voltage reduction of

10% would increase slip by about 21%.

Effects of Frequency Variation on Motor PerformanceA. Frequency greater than rated frequency normally improves power factor but decreases locked-rotor and aximum

torque. This condition also increases speed, and therefore, friction and windage losses.B. Conversely, a decrease in frequency will usually lower power factor and speed while increasing locked-rotor

maximum torque and locked rotor current.

Low Starting Voltage. Large motor may experience a considerable voltage drop (dip) at the motor terminals whenstarted due to large inrush current. Large submersible motors are particularly susceptible to low voltage startingproblems as a result of long cable runs. High inrush currents create instantaneous cable voltage drops 4-7 time therunning value, which can make starting of deep set submersible pumps difficult if not considered in the initialdesign.

Most motors will successfully start with terminal voltage down to 65% of the nameplate rated voltage. Insubmersible applications, the minimum allowable voltage, measured at the surface, should be no less than 70% ofthe motor nameplate value. Reduced voltage starting of large Hp motors is a common practice to reduce stating in-rush currents, thereby reducing “flicker dip” within the power distribution system.

FrequencyFrequency Definitions. Frequency can be defined as the number of complete alterations-per-second of analternating current and is illustrated in Figure 3-11 below:

Current is said to have been through onecomplete cycle when it has gone fromzero to maximum, to minimum, andback to zero again. Frequency is thenumber of these complete cycles overthe passage of time and is usuallyexpressed as hertz (Hz): one hertz equalsone cycle per second (cps).Predominate frequency in North Americais 60 Hz.

Frequency Standards. The predominantfrequency in the United States is 60 Hz;however, 50 Hz systems are common inother countries. A small percentage of

power distribution systems through out the world are 40 or 25 Hz based. The NEMA standard frequencies are 60and 50 hertz.

50Hz Operation of 60Hz Motors. Many motor rated for 60 Hz may be successfully operated at a 50Hz providedthe volts/Hz ratio is maintained. Operation of a 60 Hz motor at 50 Hz requires a reduction in voltage andhorsepower as shown in Table 3-3.

Figure 3-11: Alternating Current Cycle Illustration

Dual Frequency Motors. Motors that require 50 and 60 Hz operation of the same motor are non-NEMA definedmotors. Such motors are available from some manufactures by special order.

Variable Frequency Operation. Almost all three phase motors can be operated in the conjunction with variablefrequency drives (VFD). When the motor is not specifically designed for use with a VFD, it is recommended thatthe motor not be loaded beyond at its nameplate rating @ 60Hz.

AC PowerA power system is typically either single phase or three phase. Figure 3-11 illustrates the single phase a.c. powerwaveform, which is most commonly used to serve factional up to about 3 horsepower motors.

A three phase power system consists of two or more alternating currents of equal frequency and amplitude butoffset from each other by a phase angle. Figure 3-12 illustrates a three phase power systems having phases A, B

and C. Each phase is offset by 120degree, 360 degrees being the span ofone complete cycle.

From a motor standpoint, three phasemotors are simpler to construct andmaintain. They require none of thestarting enhancements required by singlephase motors. Three phase powerallows for a more powerful motor to bebuilt into a more compact housing, withgreater efficiency and smootheroperation; when compared to a singlephase motor of the same rating.

Motor Output RatingSpeed. The speed at which an induction motor operates is dependent upon the input power frequency and thenumber of electrical magnetic poles (p). The number of poles (magnetic fields set up inside the motor is a functionplacement and connection of the stator windings. The higher the frequency (f), the faster the motor runs. Themore poles the motor has, the slower it runs. The speed of the rotating magnetic field in the stator is calledsynchronous (sync.) speed. To determine the synchronous speed of an induction motor, the following equation isused:


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Table 3-3: Derating Factors for 60Hz Motors Operated at 50Hz

Motor 60Hz Motor 50 Hz Voltage OptionVoltage Rating Voltage Range (+/- %5)

230 190 200 208460 380 400 415575 475 500 -

Derate Factor (DF) .85 .90 1.00

• Rated Hp @ 50Hz = Nameplate Hp x DF • Motor Speed = 5/6 (.83) nameplate rated speed • Allowable voltage variation at derated Hp = +/- 5% • Service Factor (SF) = 1.0• Select motor overload protection for a 60Hz Amps and 1.0 SF

Figure 3-12: Three phase power waveform (current)

Sync. Speed (rpm) = 60 x 2 x frequency = 120 x fNumber of poles p


Section 3


Actual full-load (F.L.) speed (the speed at which an induction motor will operate at nameplate rated load) will beless than synchronous speed. This difference between synchronous speed and full-load speed is called slip.Percent slip is defined as follows:

Induction motors are built having rated slip ranging from less than 5% to as much as 20%. A motor with a slip ofless than 5% is called a normal slip motor. Submersible motors are of the low slip design as they are used almostexclusively for variable torque centrifugal pump applications. Motors with a slip of 5% or more are used forapplications requiring high starting torque (conveyor) and/or higher than normal slip (punch press) where, as themotor slows down, increased torque allows for flywheel energy release. The relationship between motor speed,frequency and number of poles is described in Table 3-4 below.

% Slip = Sync. Speed - F.L. Speed x 100Sync. Speed

Table 3-4: Synchronous & Appx. F.L. Speed of Std. NEMA Design B ~ AC Induction Motors

# - poles 60 Hz - rpm # - poles 60 Hz - rpm # - poles 50 Hz - rpm

Sync. F.L Sync. F.L. Sync. F.L.

2 3600 3500 10 720 690 2 3000 29004 1800 1770 12 600 575 4 1500 14506 1200 1170 14 514 490 6 1000 9608 900 870 16 450 430 8 750 720

Note: The F.L. speeds listed in the table are for surface motor, submersible motor F.L. speeds are generally slightly less as a result of the compact design.

Nameplate Horsepower. The motor nameplate Hp rating is the full load Hp output rating at the motor shaftunder rated conditions. The actual Hp output can be calculated by determining the Input Hp and multiplying it bythe motor efficiency, at the appropriate load percentage.

Torque & Horsepower. Torque and horsepower are two key motor characteristics that determine the size ofmotor for an application. Torque is merely a turning effort of force acting through a radius. It takes one pound offorce applied at a distant of one foot from the center of a shaft to produce one foot pound (ft. - lb.) of torque.Torque (T) is independent of speed.

Horsepower (Hp) takes into account speed. Turning the shaft rapidly requires more Hp than turning it slowly (ie.Hp @ 1.0 ft.- lb. and 1800 rpm < Hp @ 1.0 ft. - 1b. and 3600 rpm). Horsepower is a measure of the rate at whichwork is done. The relationship between T and Hp is:

The torque (T) - horsepower (Hp) relationship can be related to a rotary system as a function of speed as follows:

where; T = torque in ft. - lbs.rpm = speed in rev./min.

In order to produce one Hp, the shaft would have to be turned at a rate of 5252 rpm (1 Hp x (33,000 ft. -lbs./min./Hp)) / (1 ft. x 2 (ft./rev.). In terms of induction motors, full - load torque (F.L.T.) can be calculated usingthe above formulas, when the motors full -load speed (F.L. rpm) is known:

Figure 3-13 illustrates a typical speed-torque (S-T) curve for a NEMA design B induction motor. Submersible Motorsare typically constructed in accordance to NEMA design B standards and exhibit the same general characteristics.

1.0 Horsepower = 33,000 ft-lbs./min.

HP = rpm x 2π x T = rpm x T33,000 5,250

F.L.T. = Hp x 5250F.L. rpm


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Figure 3-13: Motor Speed-Torque - Current Curve (NEMA Design B)

Speed - Torque Relationship Speed - Torque - Current Relationship

Locked Rotor Torque. Locked rotor torque (L.R.T.) is the torque which the motor will develop at rest with ratedvoltage at rated frequency applied. It is also sometimes known as “starting torque” and is usually expressed as apercentage of full-load torque. The L.R.T. for NEMA design B motors range from 125 to 275% of the F.L.T. value.

Pull-up Torque. Pull-up torque (P.U.T.) is the minimum torque developed during the period of acceleration fromlocked rotor to the speed at which break down torque occurs.

Breakdown Torque. Breakdown torque (B.D.T.) is the maximum torque the motor will develop with rated voltageapplied at rated frequency without an abrupt drop in speed. Breakdown torque is usually expressed as apercentage of full-load torque. The B.D.T. for NEMA design B motors range from 200 to 300% of the F.L.T. value.

Full - Load Torque. Full-load torque (F.L.T.) is the torque necessary to produce rated horsepower at full-load speed.

Motor Current. In addition to the relationship between speed and torque, the relationship of motor current tothese two values is an important application consideration. The speed/torque curve is repeated with the currentcurve added to demonstrate a typical relationship in Figure 3-13.

Full - Load Current/Amps. The full-load current (F.L.A.) of an induction motor is the steady-state current taken fromthe power line when the motor is operating at full-load torque with rated voltage and rated frequency applied.

Locked-Rotor Current/Amps. Locked-rotor current (L.R.A.) is the steady-state current of a motor with the rotorlocked and with rated voltage applied at rated frequency. NEMA has designated a set of code letters to definelocked rotor kilovolt-amperes-per-horsepower (kVA/Hp) and are listed in Table 3-5. This code letter appears on thenameplate of all AC squirrel-cage induction motors; and can be used to estimate in -rush/start-up/L.R.A. current.The letter designations for locked motor kVA/Hp are based on full voltage and rated frequency at the motorterminals. Starting current for NEMA design B motors range from 400 to 700% of the F.L.A. for a across-the-line(AOL) start.

No - Load Current/Amps. The no-load current N.L.A will range between 30 - 40% of the motors F.L.A. value. Themajority of this current is required to establish the magnetic field within the motor.

% SYNCHRONOUS SPEED % SYNCHRONOUS SPEED


Section 3


Table 3-5: Locked-Rotor kVA/Hp Code Letters Designations

Letter Designation KVA/Hp* Letter Designation KVA/Hp* Letter Designation KVA/Hp *

A 0 -3.15 H 6.3 - 7.1 R 14.0 - 16.0B 3.15 - 3.55 J 7.1 - 8.0 S 16.0 -18.0C 3.55 - 4.0 K 8.0 - 9.0 T 18.0 - 20.0D 4.0 - 4.5 L 9.0 - 10.0 U 20.0 - 22.4E 4.5 - 5.0 M 10.0 - 11.2 V 22.4 and upF 5.0 - 5.6 N 11.2 - 12.5 - -G 5.6 - 6.3 P 12.5 - 14.0 - -

* The locked-rotor kilovolt-ampere-per-horsepower range includes the lower figure up to, but not including thehigher figure. For example, 3.14 is letter “A” and 3.15 is letter “B”.

Note: 1. The maximum motor in-rush current at start-up/Locked Rotor Amps (L.R.A.) can be quicklyapproximated by multiplying the published full load amps (F.L.A.) value by average numeric valueassociated with the NEMA code letter printed on the motor nameplated

2. Single-speed motors, starting on Y connection and running on delta connections, are marked with acode letter corresponding to the locked-rotor kVA per horsepower for the delta connection.

3. Dual-voltage motors which have a different locked-rotor kVA per horsepower on the two voltages aremarked with the code letter for the voltage giving the highest locked-rotor kVA per horsepower.

4. Motors with 60 and 50 Hertz ratings are marked with a code letter designating the locked rotor kVA perhorsepower on 60 hertz.

5. Part-winding-start motors are marked with a code letter designating the locked rotor kVA perhorsepower that is based upon the locked rotor current for the full winding of the motor.

Estimating Motor L.R.A./In-Rush Current. The relationship between motor kVA/Hp and L.R.A. for a three phasesystem is illustrated mathematically as follows:

Note: 1. The same formula can be used for a single phase motors through the elimination of the 1.73, threephase multiplication factor.

2. The L.R. kVA/Hp value is based on the NEMA code letter assignment.

Operating a motor in a locked-rotor condition in excess of 20 seconds can result in insulation failure due to theexcessive heat generated in the stator.

EfficiencyEfficiency of a motor is the ratio of its power output to input. It represents the effectiveness in which the motorconverts electrical energy to mechanical load, and is illustrated by equation as follows:

All electrical devices heat up in operation due to the losses in the windings, cores, and other machine parts.Heating represents a loss of energy and reduces efficiency. Enough power must be put into the machine (motor) toovercome these losses, in addition to the power required by the load on the motor. The power input to the motoris always greater than the power output.

The ideal motor would be 100% efficient; however this is a impossible situation as a result of motor losses (seeFigure 3-15). The efficiency of electrical submersible motors range from 80 to 90%. The efficiency generallyincreases with the size of the motor. Motors 10 Hp and larger, generally maintain high efficiency over the loadrange of 50% to 125%; however, power factor will drop rapidly with decrease in motor load. The efficiency -power factor relationship is illustrated in Figure 3-14.

Efficiency (%) = P output (Hp) x 100F.L. rpm

kVA/Hp = Amps x Volts1000 x Hp x 1.73

L.R.A. = 1000 x Hp x L.R. kVA/Hp1.73 x Volts

The relationship between efficiency and power factor, as well as economics, favor loading a motor at or near fullload. A slight increase in motor efficiency may have a significant impact on power consumption in high useinstallations.

Motor Losses. Motor losses are categorized as; (1) those which occur while the motor is energized but operatingat no load, and (2) additional losses due to the output load. Specific losses are:

1. No load losses: a. Friction windage 2. Load Losses: a. I2R Losses (stator and rotor) b. Core losses b. Stray Load Losses

The no-load losses and the conductor losses under load can be measured separately; however, the stray load lossrequires accurate input-output testequipment for determination. The stray-load loss consists of losses due toharmonic currents and flux in the motorand are difficult to measure directly.Losses in a typical 50Hp induction motoris shown in Figure 3-15. Motorsoperated under VFD/inverter conditionwill exhibit significantly higher stray loadlosses under full load conditions.


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Figure 3-14: Power Factor and Efficiency Variation by Load

Power Factor Variation by Load Efficiency Variation by Load

Figure 3-15: Typical Motor Losses - 50 Hp Induction Motor

Note: The curves indicate a general relationship.Values will vary with individual motor type andmanufacturer.


Section 3


Motor Testing. Motor efficiency is not an absolute or constant for all motors of the same design. Rather, theefficiencies of a large number of motors will fit a normal “bell curve” distribution. The nominal efficiency whichappears on the motor nameplate corresponds to the nominal, or average expected efficiency on the curve. If theefficiency of a specific motor is required, that motor must be factory tested. Most motor manufactures can providesuch testing at a additional cost. Efficiency requirements established by NEMA for three-phase surface motors aretabulated in Table 3-6.

Table 3-6: Electric Motor Efficiencies - NEMA Standard, Table 12.6

Hp 12-6B (current) 12-6C (1997) Hp 12-6B (current) 12-6C (1997)

ODP TEFC ODP TEFC ODP TEFC ODP TEFC

1 77.0 72.0 82.5 82.5 30 91.7 91.0 92.4 92.41.5 82.5 81.5 84.0 84.0 40 92.4 91.7 93.0 93.02 82.5 82.5 84.0 84.0 50 92.4 92.4 93.0 93.03 86.5 84.0 86.5 87.5 60 93.0 93.0 93.6 93.65 86.5 85.5 87.5 87.5 75 93.6 93.0 94.1 94.1

7.5 88.5 87.5 88.5 89.5 100 93.6 93.6 94.1 94.510 88.5 87.5 89.5 89.5 125 93.6 93.6 94.5 94.515 90.2 88.5 91.0 91.0 150 94.1 94.1 95.0 95.020 91.0 90.2 91.0 91.0 200 94.1 94.5 95.0 95.025 91.7 91.0 91.7 92.4 - - - - -

Note: Submersible motors will be slightly less efficient as a result of the compact design.

Basis of Testing. Most motors used in the U.S. are manufactured in accordance NEMA standard MG-1, whichincorporates test standard IEEE 112 method B for reporting motor efficiency. Other standards for reporting motorefficiency are IEC 34-2 and JEC37 which are primarily utilized in Europe and Japan respectively. When comparingmotors, the efficiency should be calculated on the same basis. A 15 Hp motor tested by IEEE 112 - method B, JEC37 and IEC 34 - 2 produced efficiency values of 87.4%, 90.1% and 89.2% respectively.

Three Phase Motors (1-200 Hp)NEMA has designated several specific types of motors, each type having unique speed/torque relationships. Therotor design is the principal factor which distinguishes the various NEMA design types. These designs are describedin Figure 3-16 along with some typical applications for each. Only the NEMA design B motors have applicability tosubmersible motors used in water supply industry. The other NEMA designs are described for completeness, asthey are used in wide range of water supply application.


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Figure 3-16: NEMA Motor Design Performance Characteristics by Design Code

Speed - Torque Performance

1) NEMA Design A&B• Starting Current: Design A - high to medium (not

defined by NEMA)/Design B - low• Starting Torque: Normal• Breakdown Torque: Normal• Full - Load Slip: Low (less than 5%)• Applications: Low starting torque/variable torque

requirements and essentially constant load, such aspumps and fans.

• Expense: Minimal

2) NEMA Design C• Starting Current: Low• Starting Torque: High• Breakdown Torque: Normal• Full-Load Slip: Low (less than 5%)• Applications: Hard-to-start loads such as positive

displacement pumps and compressors.• Expense: Moderate

3) NEMA Design D• Starting Current: Low• Starting Torque: Very High• Breakdown Torque: Not Applicable• Full-Load Slip: High (5-8%; 8-13%)• Applications: Where a combination of high

starting torque and high slip is required. Ideal forhigh inertia loads and/or for considerablevariations in load; such as; punch presses, shears,cranes, hoists, and elevators.

• Expense: High

Rotor Geometry


Section 3


Three-Phase UnbalanceVoltage Unbalance. Unbalanced line voltages applied to a polyphase motor result in unbalanced currents in thestator windings. Even a small percentage of voltage unbalance will result in a larger percentage of currentunbalance, thus increasing temperature rise and possibly result in nuisance tripping.

Voltages should be as evenly balanced as can be read on a voltmeter. If voltages are unbalanced, the ratedhorsepower of the motor should be derated, based upon the percent unbalance as shown in Figure 3-17.

Figure 3-17: Motor Derating for VoltageUnbalance

Note: Motor operated above 5% voltageunbalance is not recommended.

The percent unbalance is calculated as follows:

Example 3-1: Voltage Unbalance Motor DeratingCalculation

Given: 100 Hp/3ph motor operating @ 480V, 460V and440V measured at the motor starter is running with a 4.3%voltage unbalance (100 x 20/460).

Solution. The rated output of 100 Hp should be derated by.80% (from Figure 3-18) to 80 Hp to reduce the possibility ofdamage.

% Unbalance = 100 x (Max. Volt Deviation from Avg.)Avg. Voltage

Effects of Unbalanced Voltage on Motor Performance.• Torques: Unbalanced Voltage results in reduced locked-rotor and breakdown torques for the application.• Full-Load Speed: Unbalanced voltage results in a slight reduction of full-load speed.• Current: Locked-rotor current will be unbalanced to the same degree that voltages are unbalanced but locked-

rotor KVA will increase only slightly. Full load current at unbalanced voltage will be unbalanced in the order ofsix to ten times the voltage unbalanced.

• Temperature Rise: A 3.5% voltage unbalance will cause an approximate 25% increase in temperature rise.

Current Unbalance. Current unbalance is typically a result of heavy single-phase loads on the electricaltransmission lines or as a result of open delta secondary transformer connection serving the motor. Excessive currentunbalance in three phase motors may cause low output, overload tripping and motor failure if improperly protected.

Two criteria used in determining the acceptable levels of unbalance for submersible pumping applications are; (1)Initial installations should aim for a 5% maximum current unbalance, and unbalance should not exceed 10% forinstallations that have been in service for 6 months or longer, and (2) Current unbalance should not exceed 5% ofservice factor load or 10% at rated load for new installations. In order to maintain current unbalance withinacceptable levels, voltage unbalance must be maintained within 1-3% line to line. The formula for calculatingcurrent unbalance is described as follows:

Example 3-2: Current Unbalance Calculation

Given: 20 Hp/3 ph motor operating @ 230V. Current on each leg was measured at 50, 48 and 52A.

Solution: From the above formula, the current unbalance is 4% (52 - 50/50). When the current unbalanceexceeds 2%, as is the case this example, the motor cable leads should be “rolled” to minimize unbalance anddetermine whether it is mainly caused by the line, or as a result of motor/cable problem.

% Unbalance = 100 x (Max. Current Deviation from Avg.)Avg. Voltage


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Figure 3-18: Rolled Phases - Current Unbalance Calculation

R = 51 ampsB = 46 ampsY = 53 ampsTotal = 150 amps150 / 3 = 50 amps50 - 46 = 4 amps4 / 50 = .08 or 8%

Y = 50 ampsR = 48 ampsB = 52 ampsTotal = 150 amps150 / 3 = 50 amps50 - 48 = 2 amps2 / 50 = .04 or 4%

B = 50 ampsY = 49 ampsR = 51 ampsTotal = 150 amps150 / 3 = 50 amps50 - 49 = 1 amps1 / 50 = .02 or 2%

Calculations

Note: The installation should be left in the hookup 3 configuration

If the unbalanced currents stay with the same line leads when motor leads are rolled, unbalance is in the line.If the unbalance follows the motor leads, the unbalance is in the cable and motor, and they must be checkedfor defects.

If unbalance stays with the line leads and is in excess of 3% in the best of the three connections, consult thepower company for correction. A typical start-up procedure for submersible pumping system is outlined andillustrated below.

Checking and Correcting Rotation and Current Unbalance1. Establish correct motor rotation by running in both directions. Change rotation by exchanging any two of

the three motor leads. The rotation that gives the most water flow, or produces the greatest pressure isalways the correct rotation.

The typical phase designation of motor leads for CCW rotation viewing the shaft end is

• ph 1 or “A” - black • ph 2 or “B” - yellow • ph 3 or “C” - red

Note: ph 1, 2 and 3 may not be L 1, L 2 and L 3

2. After correction rotation has been established, check the current in each of the three motor leads andcalculate the current unbalance as explained in item 3 below, and described in example 3-1 above.

If the current unbalance is 2% or less, leave the leads as connected.

If the current unbalance is greater than 2%, current readings should be checked on each leg using each of the three possible hook-ups. Roll the motor leads across the starter in the same direction to preventmotor reversal (ie. move each lead one place to the right and move the furthest right lead to the left).

3. To calculate percent of current unbalance:A. Add the three line amp values together.B. Divide the sum by three, yielding average current.C. Pick the amp value which is furthest from the average current (either high or low).D. Determine the difference between this amp value (furthest from average) and the average.E. Divide the difference by the average and multiply the result by 100 to determine percent of unbalance.

The rolled phases/current unbalance calculation process is illustrated in Figure 3-18.


Section 3


Single Phase MotorsSingle phase (1 ph) motors are most often employed when power requirement range from fractional horsepower(Hp) - 115 to 230V to approximately 3 Hp - 230V. Single phase motor Hp ratings up to 15 Hp are available byspecial order. In the submersible motor industry, 1 ph motors are categorized as two-wire (2W) or three-wire (3W),and are described as follows:

• 2W motors require no external capacitor to facilitate a motor start and have low starting torque. 2W motors areavailable in fractional sizes up about 1.5 Hp. The most common 2W motor design used in the submersible pumpindustry is the split phase type. This design utilizes a built in capacitor in the starting winding with a centrifugalswitch, which opens at about 2/3 of full load speed engaging the running winding.

• 3W motors require a external capacitor and switching relay to start, and have higher starting torque comparedwith 2W designs, but less than 3 phase motors. 3W motors are typically available in sizes ranging from 1/3 to 15Hp. The capacitor start-induction run motor is the most widely used type 3W motor.

All single phase motors are wired to run in a specified direction at the factory (typically CCW). Some fractional Hpmodels incorporate built-in overload protection. Overload protection must be built into the starter for larger units.

Power FactorA motor can be fundamentally described as a electromagnet, power factor (pf) is a measure of the amount ofmagnetizing current required for the machine to operate.

Power factor (pf) is an important consideration when selecting a motor for a particular application since low pf mayresult in a pf penalty charges from the utility company. Since the power company must supply kVA, but typicalutility metering only kilowatts (kW) used, low motor pf requires additional kVA with low return on kW utilized;hence, pf penalties. The equation for calculating pf in a three-phase system is listed as follows:

Note: The same equation can be used for a single-phase system with the eliminationof the 1.73 term.

This equation represents a numerical method of expressing the phase difference between voltage and current in amotor circuit. The current in an induction motor lags the applied voltage, and only the component that is in phasewith the voltage varies with motor power. The relationship expressed in the above equation is shown graphicallyin Figure 3-19 A, as a vector relationship in which the numerical expression actually the cosine of the angle L.

pf = kW Input = kW1.73 x V x I kVA

Figure 3-19: Power Factor Illustration

A. Phase Angle (General) B. Phase Angle as a % of Load

pf = cos L Ip = In-phase current, Im = Magnetizing Current, IL = Total Current

Line current required for a given motor output varies inversely with power factor. Increasing pf will reducerequired line current, thus reducing voltage drop in power lines and transformers. The lagging current shown inFigure 3-19 A is actually motor magnetizing current, which is dependent upon motor design. This magnetizingcurrent is independent of motor load (ie. just as much is required at no load as at full load). Thus power factor atpartial loads is never as high as at full load). Thus power factor at partial loads is never as high as at full load, andat no load power factor is essentially zero. The relationship of load to pf for various motor sizes is illustrated inFigure 3-14.

Power Factor CorrectionIn some instances, power supply limitations make it necessary or desirable to raise the power factor (pf ) of thesubmersible pump installation. The primary reasons for improving pf are; (1) improve voltage regulation, (2) avoidor reduce utility power factor penalties and (3) reduce current flow (load) through cables, transformers and relatedappurtenances. Typical kVAR and capacitor addition correction requirements for pf improvement of submersibleinstallations are illustrated in Table 3-7.


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Table 3-7: Power Factor (pf) Improvement Capacitor Requirements @ 60Hz - 3 phase(Tabulated range of pf improvement is .82 - .85 (existing) to .92 - .95 (corrected))

Horsepower (Hp) 5 7.5 10 15 20 25 30 40 50

Capacity at 230V 80 120 140 200 300 300 320 - -

(uF) at 460V 20 30 35 50 75 75 80 85 85

kVAR Correction 1.6 2.4 2.8 4.0 6.0 6.0 6.4 6.8 6.8

Horsepower (Hp) 60 75 100 125 150 175 200 250 300

Capacity at 460V 100 160 200 450 250 90 85 115 115

(uF)

kVAR Correction 8.0 12.8 16 36 20 7.2 6.8 9.2 9.2

Note: 1. The tabulated capacitor values are for WYE - connection per phase. For DELTA - connection, use1/3rd tabulated capacity.

2. When pf is improved to 92 - 95%, a condensive (capacitive) pf may occur when load is increased orvoltage is low and this may cause a negative effect in this system. To avoid this problem, a capacitorselection for the next motor size smaller is advisable. The power company will generally request apower factor of 85% min.

3. Capacitors must be connected on the line side (upstream) of motor overload protection.4. The use of power correction capacitors in conjunction with VFD control is not recommended.

Power factor correction is achieved when capacitive reactance (capactive reactive power in kVAR) is added inparallel to the power system through the use of capacitors. The capactive reactance created by the capacitorscancel the inductive reactance (inductive reactive power in kVAR) affect created by induction motors.

From a system stand point, over-excited synchronous motors are often used as “synchronous condensers” toimprove pf. Generators operated in a under-excited mode are also used to improve system pf in heavy loadedinductive circuits. A detailed discussion of pf correction by rotating apparatus is outside the scope of this manual.

Measuring Power Factor. The power factor for a single-phase alternating current (AC). circuit can be calculatedusing measurements obtained form a voltmeter, ammeter and wattmetter. Plugging the measured values into theformula; pf = W/ (E x I) will yield the single phase pf. Power factor in three-phase A.C. circuits can be calculatedin the same manner averaging voltage and current, and recording the value obtained from the power utility watt-hour meter. The recorded measurement when inserted into the formula; pf = W/ (E x I x 1.73) will yield the threephase pf.

There are two basic methods for improving the power factor of a motor for a particular application:

1. Purchase a motor with an inherently high power factor.2. Install power factor correction capacitors. Capacitors draw leading current as opposed to the lagging current

drawn by induction motors. Placing capacitors in parallel with the motor windings will result in leading currentoffsetting some of the lagging current.

In a power distribution system, over excited synchronous motors are often used as a synchronous condenser toimprove system pf.


Section 3


Environmental ConsiderationsEnvironmental consideration for submersible pump motors are principally restricted to ambient fluid temperature,corrosivity, pressure and the presence of abrasive. Motor enclosure requirements for surface motor are discussedbelow, as they have significant use in supporting pumping plant operations.

Surface Motor Enclosures. The type of enclosure required is dependent upon the surrounding atmosphere inwhich the motor is installed and the amount of mechanical protection and corrosion resistance required. The twogeneral classes of motor enclosure are open and totally enclosed. An open machine is one having ventilatingopenings which permit passage of external air over and around the winding of the motor. A totally enclosedmachine is constructed to prevent the free exchange of air between the inside and outside of the motor, but notsufficiently enclosed to be termed air-tight. Derivatives of these two basic enclosures are described as follows:

(1) Open Enclosures. Open enclosures can be provided in a variety of configurations suitable for indoor or outdoorapplications. The primary enclosures configuration for water supply pumping applications are:

• Open Dripproff (ODP): Open dripproff motors are designed to be internally ventilated by ambient air, havingventilation openings constructed so that successful operation is not affected when drops of liquid or solidparticles strike the enclosure at any angle from zero to 15 degree downward from vertical. Drip proof motors aretypically used in relatively clean, indoor applications.

• Weather Protected Type 1 (WPI): A weather protected type I machine is an open machine suitable for outdooruse. Ventilating passages are constructed as to minimize the entrance of rain, snow and air-borne particles to theelectric parts and are designed to prevent the passage of a cylindrical rod 3/4-inch in diameter.

• Weather Protected Type II (WPII): A weather protected type II machine has the same features as a weather-protected type I machine. In addition, ventilating passages at both intake and discharge are arranged so thathigh-velocity air and air-borne particles blown into the machine by storms or high winds can be dischargedwithout entering the internal ventilating passages leading directly to the electric parts of the machine. WPIImotors have provisions for air filters.

(2) Totally Enclosed. Totally enclosed motors are designed so that there is no free exchange of air between theinside and the outside of the enclosure, but not sufficiently enclosed to be airtight. Totally enclosed motors may beof three basic types of construction.

• TEFC (totally enclosed fan-cooled): This type includes an external fan mounted on the motor shaft. This fan isenclosed in a fan casing which both protects the fan and directs the output air over the motor frame for cooling.

• TEAO (totally enclosed air-over): This type is similar to TEFC designs except that the cooling air being forcedover the motor frame is provided by a fan which is not an integral part of the motor.

• TENV (totally enclosed non-ventilated): This type of construction does not require forced air flow over the motorframe for cooling.

• XPRF (Explosion proof): Totally enclosed motor designed to withstand an internal explosion of gas or vapor.Will also prevent internally generated sparks from igniting surrounding vapors.

Hazardous (Classified) Locations. Special designed electrical enclosures are required for hazards atmospheres.The hazard classes, are defined by Underwriters Laboratories (U.L.), the National Electric Manufactures Association(NEMA) and the National Electric Code (NEC). The two basic classes are:

Class I Explosion Proof. An explosion proof motor/ enclosure is designed to withstand an explosion of a specifiedgas or vapor which may occur within it and to prevent the ignition of the specified gas or vapor surrounding theenclosure.

Class II Dust - Ignition Proof. A dust-ignition proof motor/enclosure is constructed in a manner which will excludeignitable amounts of dust or amounts which might affect performance or rating, and which will not permit arcs,sparks, or heat generated inside the enclosure to cause ignition of exterior accumulations or atmospheric suspensionof a specific dust and/or in the vicinity of the enclosure.

The various atmospheres defined within the two classes have been divided into groups dependent upon theexplosive characteristics of the materials. The class and group of service must appear on the motor/ enclosurenameplate, along with an identification number which identifies a maximum operating temperature. A completedescriptive summary of the various NEC hazardous locations are described in Table 3-8.


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Table 3-8: National Electric Code (NEC) Hazardous Location Classifications

CLASS I: Areas in which flammable gases or vaporsmay be present in the air in sufficient quantities to beexplosive (NEC-500-5).

Group A: Atmospheres containing acetylene.

Group B: Atmospheres containing hydrogen gases orvapors of equivalent hazards such as manufacturedgas.

Group C: Atmospheres such as cyclopropane, ethylether, ethylene, or gas or vapors of equivalent hazard.

Group D: Atmospheres such as acetone, alcohol,ammonia, benzene, benzol, butane, gasoline, hexane,lacquer solvent vapors, naphtha, natural gas, propane,or gas vapors of equivalent hazard.

CLASS II: Areas made hazardous by the presence ofcombustible dust (NEC-500-6).

Group E: Atmospheres containing electricallyconductive combustible metal dust includingaluminum, magnesium and their commercial alloys,regardless of resistivity. Includes any dust of a similarhazard characteristics.

Group F: Atmospheres containing combustible carbonblack, charcoal, or coke dusts having more than 8%total volatile material. Includes other similar dusts sosensitized that they present an explosion hazard.

Group G: Atmospheres containing electrically non-conductive combustible dust. Such as containing flour,starch or grain dust.

CLASS III: Areas in which there are easily ignitable fibers or flyings present, due to the type of material beinghandled, stored or processed (NEC-500-7)

Note: Fibers and flying are not likely to be suspended in the air, but can collect around machinery or lightingfixtures, where heat, a spark or hot metal may ignite them.

Division I (NEC-800-5, 6, 7): In a normal situation hazard would be expected to be present in everydayproduction operations or during frequent repair and maintenance activity.

Division II (NEC-500-5, 6, 7): In the abnormal situation material is expected to be confined within closedcontainers or closed systems and will be present through accidental rupture, breakage or unusual faultyoperation

Note: Hazardous classifications are made by class, group and division (ie. Class 1/Group D/Division 1)

Altitude. Altitude has no practical significants with submersible motors as they are submerged in the fluid to bepumped. Pump NPSH performance is affected by a altitude to some degree and can create submersible systemperformance problem under low submergence conditions. Surface motors generally require no derating for altitudebetween sea level and 3300 feet (1000 meters).

Temperature. Submersible motors are typically performance rated based on a 30°C (86°F) ambient temperature.Surface motors are rated at a ambient air temperature of 40°C (104°F).

When ambient temperatures exceed the 30°C for submersible motors (40°C for surface motors). The temperaturerise produced in the motor can be offset by; (1) Reducing the load and consequent motor losses. A motor rated for40°C/30°C ambient temperature and operating in a 50°C/40°C ambient, will, if rated 1.15 service factor (SF), carryrated horsepower (Hp) with no overload reserve (SF = 1.0) and, if rated 1.0 carry 90 percent of rated Hp, or by (2)Applying a special motor design.

The temperature rating and/or service duty can be improved by using alternate motor designs; which incorporatehigh temperature insulation systems, special lubrication and/or cooling fluid, and heat transfer improvements.Submersible motors temperaturing rating generally assume a minimum fluid velocity of .5 - 1.0 fps past the motor atrated temperature, for heat dissipation purposes.


Section 3


Insulation SystemsMotor insulation material design temperature and the allowable insulation system temperature rise are generallyexpressed in terms of “class”. The insulation temperature class rating and allowable temperature rise are not thesame value. IEEE standards rate motor insulation material for continuous duty as follows:

• Class A, rated 105°C (220°F) • Class B, rated 130°C (265°F)• Class F, rated 155°C (310°F) • Class H, rated 180°C (355°F)

When the rated temperature of the insulation material is exceeded, it is estimated that the insulation life isdecreased by 1/2 for every ten degrees above the rating. By using higher temperature rated materials, more heatlosses in the motor can be tolerated. The insulation class and ambient temperature rating are identified on themotor nameplate.

NEMA standards specify permissible temperature rises above a 40°C and 30°C ambient temperature, for surface andsubmersible motors respectively. The standards are based on/take into consideration the type of insulation in themotor and other motor design, and application considerations. Some motors operate at higher temperatures thanothers, but none should exceed the temperature rating of the insulation. NEMA standards for temperature rise,above the temperature of the cooling medium, shall not exceed the values given in Table 3-9.

Table 3-9: *Allowable Temperature Rise based on Insulation System Class

Motor Enclosure Type *Class of Insulation System

A B F H

a. Open enclosure designs (ODP, WPI and WPII) 60°C 80°C 105°C 125°C(40°C) (60°F) - (90°C)

b. All open enclosure motors with 1.15 or higher service factor 70°C 90°C 115°C -(50°C) (60°C) - -

c. Totally enclosed fan cooled (TEFC) motors, including variations 60°C 80°C 105°C 125°C(55°C) (75°C) - (110°C)

d. Totally enclosed nonventilated (TENV) motors, including variations 60°C 85°C 110°C 135°C(55°C) (60°C) - (115°C)

e. Motors with encapsulated windings and with 1.0 service factor, 65°C 85°C 110°C -all enclosures - - - -

* Average temperature rise is determined by a change of resistance. The allowed temperature rise measured by athermometer will be lower and are identified by brackets ( ) in the table.

Note: Tabulated values are based on:1. Temperature of the surrounding air does not exceed 40°C (104°F)2. Voltage does not vary more than 10% above or below the nameplate rating.3. Frequency does not vary more than 5% above or below the nameplate rating4. Both voltage and frequency do not vary the maximum amount given in (2) and (3) simultaneously.

The combined variation is limited to 10%.5. Altitude does not exceed 1000 meters (3300ft.)

Submersible motors used in the water supply industry are typically designed for a class A temperature rise, with aclass F insulation system. Surface motors commonly used for water supply applications employ a class H insulationsystem and a class B temperature rise.

Rules of ThumbThe following rules of thumb may be applied to motors used in water supply applications in the absence of specificmotor and load data:

• The average current draw for a 3 ph motor @ 575V will be approximately 1.0 Amps/Hp• The average current draw for a 3 ph motor @ 460V will be approximately 1.25 Amps/Hp• The average current draw for a 3 ph motor @ 230V will be approximately 2.5 Amps/Hp• The average current draw for a 1 ph motor @ 230V will be approximately 5.0 Amps/Hp• The average current draw for a 1 ph motor @ 115V will be approximately 10.0 Amps/Hp• Motor torque equals approximately 3ft. - lbs./Hp @ 1800 prm• Motor current varies in direct proportion to input voltage (ie. A motor rated 100 A @ 460V will be fully loaded at

95 A @ 483V (460/483 = .95)• Motor torque varies with the square of voltage (ie. @ 90% of motor rated voltage - 81% of rated torque will be

developed).• Motor starting current is typically 5 to 7 times rated full load motor current.• For every 1 Hp of motor load, 1 kVA of transformer capacity is required (ie. 100 Hp pump load requires a 100

kVA transformer bank.


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Section 3

Section 3C Motor Starting 3-27

3C MOTOR STARTINGFull Voltage StartingThe across-the-line (ATL) starting method is the least expensive way to start a motor from an initial cost standpoint,and is the most commonly used starting method for smaller motors. The ATL starting method results in the highestinrush current values; however, connections and starter operation are greatly simplified. All standard motors aredesigned for full voltage ATL starting.

Many U.S. power utilities limit the maximum motor size to 25 Hp or less when started across-the-line, in order toreduce nuisance “flicker dip” on transmission lines. Figure 3-20 provides a typical schematic control diagram andthe associated current vs. time profile for a ATL motor control scenario.

Figure 3-20: Across-the-Line (ATL) Starting Illustration

Typ. ATL Control Schematic Time vs. Inrust Current

The ATL starting method will always provide the lowest internal heat generation in the motor and the higheststarting torque. Many submersible motor/pump manufactures recommended motors larger than 60 Hp (45kW) bestarted using some form of reduced voltage/inrush starter, even if allowed by the power utility. The mechanicalstresses associate with ATL starting of large horsepower motors can significantly reduce motor life.

Reduced Voltage/Inrush StartingAutotransformer (AF) Starters. Autotransformer starters permit the use of standard motors and providemaximum starting torque per ampere of line current. An autotransformer reduces the voltage at the motor terminalsby a fixed ratio. Taps provided on the autotransformer are usually rated at 50%, 65% and 80% of the line voltage.The reduction in inrush current and starting torque (assuming a nominal voltage of 480VAC) are as follows:

Inrush Current Start TorqueVoltage tap Starting Volts (% of F.L.) (% of F.L.)

80 384 480% 64%65 312 390% 42%50 240 300% 25%

The essential elements of an autotransformer starter are the transformer and a switching arrangement. Theswitching contactors must connect the motor to a reduced-voltage tap for starting, and then transfer the motorconnection directly to the line for normal operation.


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Section 3C Motor Starting3-28

There are two main methods for switching from the autotransformer connection to the line connection. The twomethods are commonly referred to as “open transition” and “closed transition”. The open transition method resultsin the motor being momentarily disconnected from the power source during switching. Consequently, there can bea extremely high current and torque surge when the motor is connected across the full-voltage line for low inertialoads. This high inrush transfer can be avoided by using a closed-transition method. The Korndorfer method ofclosed transition maintains a connection to the power source during the switching from start to run, by a transfersequence which keeps a portion of the transformer winding in series with the motor until the motor is connecteddirectly to the line. The closed-transition method is the preferred method for autotransformer starting in thesubmersible motor industry; however, under high inertia pump loads (> 60Hp), the open-transition method mayprovide acceptable inrush and motor stress reduction.

Figure 3-21 provides a typical schematic diagram of a closed transition autotransformer starter and the associatedcurrent vs. time profile. Autotransformer starters are relatively expensive, but very reliable.

Figure 3-21: Autotransformer (AF) Starting Illustration

Typ. Closed-Transition AF Schematic Time vs. Inrush Current

In submersible applications, the tap settings on the AF depends on the percentage of the maximum allowable cablelength used in the system. If the cable length is less than 50% of the maximum allowable (see Table 4-18), eitherthe 65% or 80% taps may be used. When the cable length is more than 50% of the allowable, the 80% tap shouldbe used.

Wye - Delta (YD) Starters. A wye-delta connectable motor has six leads brought out, which allow the motor to beconnected in either a wye or delta configuration. When connected in a wye configuration, nominal line voltage isonly 57% of the winding’s rating (about 275 volts for 480VAC nominal voltage). This reduces the inrush current andthe starting torque to approximately 33% of the full voltage value.

The YD starting method is comparable in performance to the autotransformer (AF) method, and like the AFmethod, it can be provided configured for a open or closed transition. The closed transition is recommended forsubmersible applications of 60Hp or less. Above 60Hp, the closed or open transition configuration is generallyacceptable as the rotational inertia of larger equipment will reduce the magnitude of the current switching spikeassociated with open transition starting. The open transition YD starter is always less expensive. Both methods aredescribed as follows:

Open transition. The motor is started by connecting it in a wye configuration as described above via electricalcontractors. After a time delay relay times out, the motor is automatically reconnected in a delta configuration with


Section 3


a separate contactor. The delta contactor is essentially the “run” contractor, which applies full line voltage to themotor after it has already started, but before it is up to full running speed.

A YD closed circuit transition starter works basically the same as an open transition YD starter, except a thirdcontractor will connect a set of three resistors across the line during the transition from the wye to the deltaconnection. This allows the motor to remain connected to the power source without disconnection from the line,avoiding the high inrush switching current transition.

Figure 3-22 provides a typical schematic diagram of a closed transition wye-delta starter and the associated currentvs. time profile.

Figure 3-22: Wye-Delta (YD) Starting Illustration

Typ. Closed-Transition YD Control Scheme Time vs. Inrush Current

The YD starting is the most common method for reducing start-up torque and inrush current in Europe. The use ofYD starters in the U.S is very limited with submersible motors, as the motor must be specifically configured for theapplication. Submersible system employing the YD starting scheme are generally more expensive, as separatepower cables and motor leads are required in each installation. Submersible motors configured for YD starting (twomotor lead sockets in lieu of one) are generally 5% more expensive than standard motors.

Soft Start (SS) Starters. A soft starter is an electronic solid state device which is used to reduce motor inputvoltage at start-up, and consequently starting current. Soft starters provide smooth, stepless acceleration anddeceleration of AC induction motors from zero to full speed over an adjustable time period. Inrush current can bereduced to 2-3 times the full load operating current. Figure 3-23 illustrates the relationship between input voltage,starting current and time.

In submersible pumping applications, acceleration and deceleration ramp rates should be limited to 3 seconds,longer ramp rates contribute to motor heating. The 55% starting voltage shown in Figure 3-23, is the minimumvoltage recommended in order to achieve a submersible motor start. The start-up output voltage for SS areadjustable, which can be raised to compensate for cable voltage drop or unusual torque requirements.

The electronic nature of SS produce harmonic waveform distortion (noise) on power supply distribution system.The magnitude of the harmonic distortion is generally less than with a comparable variable frequency drive (VFD)and rarely requires special attention. In general, it is recommended to install a bypass contactor in conjunction withthe soft starter so that the motor runs ATL during operation. Switching to ATL operation after start-up will reducepower loss and SS wear.


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Figure 3-23: Soft Start - Voltage/Current/Time Relationships

Current vs. Time Voltage vs. Time

Part Winding (PW) Starting. A part winding motor has two identical windings and six motor leads. Energizingone winding at full line voltage, will allow approximately 60% of the normal starting current (400% of full loadcurrent) to flow producing approximately 50% of the full load torque. After a time delay relay times out, thesecond winding bringing both current and torque to their full rated values. PW starters have two sets of runningcontactors with two sets of overloads for half the motor current. Starting time is typically 1 to 3 seconds beforeenergizing the second contactor.

PW starters will reduce inrush current, but the motor heating rate will increase considerably. There are no standardperformances requirements for PW starting; therefore, a motor started in this manner may fail to accelerate a high-inertia variable torque (pump) or constant torque load. PW starters require special winding connections whichmust be specified at the time the motor is ordered. Most submersible motor manufactures do not wind motors forPW start applications.

Figure 3-24 provides a typical schematic diagram of a part winding starter and the associated torque vs. speed curve.

Figure 3-24: Part Winding (PW) Starting Illustration

Typ. Half Winding, Part Wind Control Scheme Torque vs. Speed


Section 3


Table 3-10: NEMA Three Phase Starters

Maximum Horsepower

Full Voltage Autotransformer * Part Winding Wye-DeltaStarting (ATL) Starting (AF) Starting (PW) Starting (YD)

200V 230V 460V 200V 230V 460V 200V 230V 460V 200V 230V 460V575V 575V 575V 575V

Table 3-11: NEMA Single Phase Starters

NEMA Maximum Horsepower – Full Voltage (ATL) Starting

Size 115V 230V

00 1/3 10 1 21 2 3

1 1/2 3 52 - 7 1/23 - 15

000123456789

1 1/23

7 1/210254075150---

1 1/23

7 1/2153050100200300450800

251025501002004006009001600

--

7 1/210254075150---

--

7 1/2153050100200300450800

--

1025501002004006009001600

--

10204075150----

--

102550751503004507001300

--

15407515035060090014002600

--

102040601503005007501500

--

102550751503505008001500

--

154075150300700100015003000

NEMASize

* Part winding starting in not applicable to submersible operations


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Table 3-12: NEMA/IEC Enclosure Ratings (Conversion of NEMA classifications to IEC designations)

NEMA type no. Applications

IEC class

1 General Purpose - Indoor; Protects against dust and light, indirect splashing but isnot dust-tight. Primarily prevents contact with live parts. Used indoors and undernormal atmospheric conditions.

IP10

2 Dripproof - Indoor; Similar to Type 1 but with addition of drip shields; used wherecondensation may be severe, such as cooling rooms or laundries.

IP11IP30

3 and 3S Weather Resistant - Outdoor; Protects against weather hazards such as rain, dustand sleet; used outdoors on ship docks, construction work, tunnels and subways.Both 3 and 3S enclosures are dust tight and raintight. The 3S enclosure is sleetproof, while the type 3 enclosure is sleet tight

IP54IP64

3R General Purpose (Rain proof and Sleet Resistance) - Outdoor; Provides a degreeof protection against falling rain and ice formation. Meets rod entry, rain, externalicing, and rust-resistance design tests.

IP14

4 and 4X Watertight (wash down duty) - Indoor or Outdoor; Must exclude at least 65 gpmof water from 1-in. nozzle delivered from a distance not less than 10 ft for 5 min.Used outdoors on ship docks, in dairies and in breweries. Both 4 and 4X enclosuresare watertight and dusttight. The 4X enclosure is corrosion resistance and sleetresistant, while the type 4 enclosure is sleet resistant.

IP56IP66

5 Dusttight-Indoor; Provided with gaskets or equivalent to exclude dust; used in steelmills and cement plants.

IP52

6 and 6P Submersible-Indoor & Outdoor; Design for occasional submersion in water and isdependant on specified conditions of pressure and time. In addition to beingsubmersible, both enclosures are watertight, dusttight and sleet resistant. Used inquarries, mines, and manholes subject to occasional flooding

IP67

7 Hazardous (Air-Break) - Indoor; For use in Class I, Groups A, B, C, and Denvironments as defined in the NEC.

-

8 Hazardous (Oil Immersed) - Indoor or Outdoor; For use in locations classified asClass I, Groups A, B, C, and D as defined in the NEC.

-

9 Hazardous (Air-Break) - Indoor or Outdoor; For in locations classified as Class II,Groups E, F, or G as defined in the NEC.

-

10 Mine Duty (Bureau of Mines); Meets the requirements of the Mine Safety andHealth Administration (MSHA) per 30 CFR Part 18 (1978).

-

11 General Purpose (Oil Immersed) - Indoor; Protects against the corrosive effects ofliquids and gases. Meets drip and corrosion resistance tests. Corrosion - Resistantand Dripproof

-

12 and 12K Industrial Use (Dusttight and Driptight) - Indoor; Provides some protectionagainst dust, falling dirt, and dripping noncorrosive liquids. Meets drip, dust, and rustresistance tests.

IP52ID64

13 General Purpose (Oiltight and Dusttight) - Indoor; Primarily used to provideprotection against dust, spraying of water, oil, and noncorrosive coolants. Meets oilexclusion and rust resistance design tests.

IP54IP65

Note: 1. The NEMA to IEC cross - reference classification are for reference only. 2. The NEMA higherarchy for resistance to a particular environmental factor, are: tight, proof, and

resistant.3. The above descriptions are a summary of the NEMA standards for enclosures.


Section 3

Section 3D Grundfos Controllers 3-33

3D GRUNDFOS CONTROLLERSCU 3 Motor Controller and ProtectorThe CU 3 is an electronic control unit designed for monitoring and protection of motors, machines, cables andcable joints with rated currents up to 400 A.

The CU 3 is designed for rated voltages of 200-575 V, 50-60 Hz.

It can communicate with the GRUNDFOS R100 remote control and be fitted with a module for RS-485 BUScommunication. (See Product Information “CU 3 with R100” and “CU 3 with Communication Module RS-485.”)

The CU 3 monitors the following parameters:• System insulation resistance to earth before start.• Motor temperature.• Current consumption and asymmetry.• Supply voltage.• Phase sequence.

The CU 3 protects the installation against:• Dry running in pumping systems.• Incipient motor defect.• Too high motor temperature.• Supply failure

As standard, the CU 3 incorporates:• Time relay for

– Star-delta starting and– autotransformer starting.

• Relay output for external alarm.

The CU 3 can be expanded to offer the followingfunctions:

Remote Control R100: Wireless infra-red remote control by means of the R100 enables change of factory settingsand monitoring of the installation by calling up actual operating data, e.g. current consumption, supply voltage,operating hours and power consumption.

External Sensors: Reception of data from external sensors by means of an SM 100 sensor module and controlaccording to the data received, e.g. flow rate, pressure, water level and conductivity.

Communication Module RS-485: Monitoring and communication via a BUS (GRUNDFOS BUS protocol =GENIbus), a modem or radio, e.g. PC-based control/monitoring.

Note: If communication with equipment not supplied by GRUNDFOS is desired, a gateway is required.

Each expansion possibility will be described in separate product information documents.

Figure 3-25: CU 3 Motor Controller


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Section 3D Grundfos Controllers3-34

Table 3-13: CU 3 Motor Controller – Indicator Lights

Operating andFault Signal Functions Description

Power on The CU 3 is live.

Motor on Permanent light indicates that the starting input is activated. Flashing light indicates that a starting delay has been set.

Ground failure The insulation resistance to earth is lower than the set value.

Motor temperature The motor temperature is higher than the set value.

Dry running (flashes) Flashing light indicates that the motor current consumption is lower than 60% of theset current value. this is an indication of dry running.

Overload (on) Constant light indicates that the measured current value is higher than the set value.

Undervoltage (flashes) Flashing light indicates undervoltage.

Overvoltage (on) Constant light indicates overvoltage.

Current unbalance The measured current asymmetry is higher than the set value.

Phase sequence The phase sequence is changed.

Table 3-14: CU 3 Motor Controller – Factory Settings

Parameter Stop Limit Measuring Accuracy*

Insulation resistance 20 kΩ ±10%

Motor temperature 75°C ±3°C

Dry running 60% of set current value ±2%

Overload 0 A ±2%

Undervoltage –10% ±2%

Overvoltage +10% ±2%

Current unbalance 10% ±2%

*The measuring accuracy is stated as a guide in relation to the maximum values.

Other Factory SettingsPhase Sequence: L1 - L2 - L3 Resetting of Fault Indications: AutomaticRelease Time for Fault Indications: 4.5 sec.Star Connection Time for Star-Delta and Autotransformer Starting: 0.5 sec.

Factory Settings

Table 3-15: CU 3 Motor Controller – Signal Converter Specifications

Measuring Range 1-12 A 10-120 A 100-400 A*

Frequency range 50-60 Hz 50-60 Hz 50-60 Hz

Maximum continuous voltage 800 VAC 800 VAC 800 VAC

Test voltage (1 minute) 3 kVAC 3 kVAC 3 kVAC

Maximum intrinsic consumption 0.02 VA 0.02 VA 0.02 VA

Accuracy CI 3 CI 1 CI 1

*Single-turn transformer


Section 3


CU 3 with R100 Remote ControlThe remote control R100 is used for wirelesscommunication with the CU 3. The R100communicates via infra-red light. Duringcommunication, there must be visual contact betweenthe CU 3 and the R100.

The R100 offers possibilities of setting and statusdisplays for the CU 3.

When the communication between the R100 and CU 3has been established, Motor temperature will flash.

For general use of the R100, see the ProductInformation for this unit.

Figure 3-26: CU 3 with R100

Voltage VariantsNominal Voltages:3 x 200 V3 x 220 V3 x 230 V3 x 240 V3 x 360 V3 x 380 V3 x 400 V3 x 415 V3 x 440 V3 x 460 V3 x 500 V3 x 575 V

Voltage Tolerance+15 / –25% of nominal voltage

Mains Frequency45-65 Hz

Power Consumption20 W

Back-Up FuseMaximum 10 A

Output RelaysMaximum 415 VAC/3 A, AC 1

Enclosure ClassIP 20

Distance Between CU 3 and MotorMaximum 100 meters

Ambient TemperatureMinimum –20°CMaximum +60°C

Storage TemperatureMinimum –20°CMaximum +60°C

ApprovalsThe CU 3 complies with VDE, DEMKO, EN, UL and CSA.

CE-marked

WeightsCU 3: 1.5 kg.Signal converters 1-12A and 10-120 A: 0.9 kg.3 single-turn transformers 100-400 A: 0.9 kg.

CU 3 Technical Specifications

R100 MenusThe following menus are shown in the R100 display.

A. Operation• Display of warning and stop indications.• Display of fault indications reset automatically.• Possibility of stop/start.

B. StatusDisplay of:• Motor temperature.• Current and voltage values.• Average of supply voltage.• Average current of the three phases.• Actual current unbalance.• Actual insulation resistance to earth.• Phase sequence and frequency.• Actual and total power consumption.• Total number of operating hours.• Value measured by an external sensor.• Power consumption per m3 pumped liquid.

C. LimitsDisplay and setting of:• Motor temperature.• Current consumption.• Voltage variations.• Insulation resistance.• Current unbalance.• External sensor.

D. InstallationSetting of:• Automatic or manual resetting of fault indications.• Release time for fault indications.• Star connection time for star-delta or autotransformer starting.• Starting delay when first started, e.g. after supply failure.• Minimum start cycle time.• On/off of groundwater lowering function.• Run/stop times for groundwater lowering.• Electronic numbering of CU 3 units.• On/off of power and temperature measuring function.• External sensor type.• Maximum value of external sensor.• Groundwater lowering by means of level sensors.• On/off of external sensor with zero offset.

R100 Menu Structure ScreenThe menu structure for the R100 and CU 3 is divided into five parallel menus, each including a number of displays.See Figure 3-28.


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Figure 3-27: R100 Remote Control

Dimension: H x W x D = 7" x 3" x 1"


Section 3


Figure 3-28: R100 Menu Structure Screen

CU 3 with SM 100 Sensor ModuleThe SM 100 is a sensor module designed as anaccessory for the CU 3, see Figure 3-29.

The module can be connected to eight analog sensorsand have eight digital inputs for connection tocontacts.

The SM 100 can communicate via BUS (GRUNDFOSBUS protocol = GENIbus).

The SM 100 can be used as a stand-alone module inconnection with equipment not supplied byGRUNDFOS. This requires a gateway, however. Thegateway is not available from GRUNDFOS.

BUS communication between several SM 100 modulesand CU 3 units enables central control and monitoringof complex systems.

Figure 3-29: SM 100 Sensor Module


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G100 Gateway Communications InterfaceG100 is a Gateway enabling communication of operatingdata e.g. measured values, setpoints, etc., betweenGrundfos products equipped with a Grundfos GENIbusinterface and a main network for control, adjustment andmonitoring of operation.

Furthermore, G100 has 4 digital inputs for optional use.As an example, a digital input could be used for themonitoring of an Uninterruptible Power Supply (UPS).

Data Logging. Besides the possibility of datacommunication, G100 also offers data logging of up to350,000 time-stamped data. Subsequently, the logged datacan be transmitted to the main system or PC for furtheranalysis in e.g. a spreadsheet or the like.

For the data logging the software tool “PC Tool G100 Data Log” is used. This tool must be ordered separately.

Applications. As show in the illustration in the front page, G100 can be used within various areas, e.g. watersupply, water treatment, wastewater and industry.

Such applications are characterized by the fact that downtime causes high costs and that extra investments are oftenmade to achieve maximum reliability.

G100 is made for customers requiring continuous, optimum operation and who need to know specific operatingdata from each individual pump unit and who are not satisfied by calculated operating data or total measuringswhich are often based on many units.

Installation. G100 is installed by the system integrator. G100 is connected to Grundfos GENIbus and to the mainnetwork. From a management system on the main network all units on the Grundfos GENIbus can then becontrolled.

Figure 3-30: Grundfos G100 Gateway


Section 3


The floppy disk “G100 Support Files” comprises examples of programs to be used when G100 is connected to thevarious main network systems, and a description of the data points available in Grundfos products with GENIbusinterface.

When G100 is installed the software tool “PC Tool G100” can be used. This tool must be ordered separately.

Technical DataOverview of Protocols

Main System Software ProtocolInterbus-S PCPProfibus-DP DPRadio Satt Control COMLIModem Satt Control COMLIPLC Satt Control COMLIFuture Systems –

Other Connection FeaturesGENIbus RS-485: Up to 32 units can be connectedService port RS-232: For direct connection to PC or via modemDigital Inputs: 4

Logging Capacity2 Mb – approx. 350,000 time-stamped dataVoltage Supply: 1 x 110 - 240 V, 50/60 HzAmbient Temperature: In operation: –20°C - +60°CEnclosure Class: IP 20Weight: 1.8 kg

AccessoriesSoftware

• PC Tool G100 (ordered separately)• PC Tool G100 Data Log (ordered separately)• PC Tool G100 Support Files (supplied with product)


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Figure 3-31: Grundfos G100 Gateway Network Diagram

G100 NetworkG100 can be connected to a GRUNDFOS GENIbus system enabling data communication between a main networkand any unit connected to the GENIbus. It is possible to connect 32 units to GENIbus. A unit may be a UPE pumpwith GENIbus connection, a CU 3 control unit, etc. The main network may be another fieldbus or a radio, modem,PLC or a direct RS-232 connection.

Information retrieval: Information such as a measured values, operating status, alarm status, configurationparameters and more can be retrieved from each individual unit via G100.

Remote configuration: Setpoints, commands and configuration parameters can be sent to the GENIbus units viaG100.

Reference: The floppy disk, “G100 Support Files,” contains an overview of the data which can be communicatedbetween the main network and the different types of Grundfos products having a GENIbus connection.


Section 3


G100 Technical Data

Table 3-16: G100 Basic Version

Mains supply• Rated voltage 100 - 240 V AC

Voltage tolerance +15/–25% of rated voltage

Mains frequency 45 - 65 Hz

Power consumption 6 W

Construction• Number of slots • 2 (1 for the mother board and 1 for one expansion board)• Dimensions (W x H x D) in mm • 73 x 227 x 165• Weight (incl. expansion board) • 1800 g

Operating range• Ambient temperature during operation • –20°C to +60°C• Transportation and storage temperature • –20°C to +60°C• Relative air humidity • Maximum 95% (without condensation)

Materials, housing Steel

Enclosure class IP 20

Approvals G100 has been CE marked

CPU• Processor • Intel 80251• Instruction size • 16-bit• Processor speed • 20 MHz

Flash• Memory size • 2MB – minimum 350,000 time-stamped samples

GENIbus connection• Bus • RS-485 up to 32 units• Connection • 9-pin D-sub male connector• Galvanically separated • Yes• Cable • 18-22 gauge screened 2-core cable

• Maximum cable length: 1200 m

Connection for service/analysis• Serial • RS-232• Connection • 9-pin D-sub male connector• Galvanically separated • No

Real time clock• Accuracy • +/– 5 min/year• Battery • DC 3 V, Lithium battery for preservation of real time clock

• during power off.• Battery durability • When in use > 5 years; when stored > 10 years

Digital inputs• Number of inputs • 4• Input • External potential-free NO-contact• Logic “0” • Open (U > 3.2 V)• Logic “1” • Closed (U < 0.9 V)• Connection • 9-pin D-sub male connector, screened cable

Visual indication• Operating status • 6 light-emitting diodes


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Table 3-17: Interbus-S Expansion Board

Interbus-S connection• Communication chip • SUPI III• Connection in • RS-485, 9-pin D-sub male connector• Connection out • RS-485, 9-pin D-sub female connector• Interface • Remote bus (local bus not supported)• Protocol • PCP (Peripheral Communication Protocol)• Interface converter • Converter from RS-485 to optical fibre available from

• Phoenix ContactVisual indication• Operating status • 4 light-emitting diodes

Table 3-18: Profibus-DP Expansion Board

Profibus-DP connection• Communication chip • SPC3• Communication speed • 9.6 kbaud to 1.5 Mbaud• Connection • RS-485, 9-pin D-sub male connector


Table 3-19: Radio/Modem/PLC Expansion Board

Radio/Modem/PLC connection• Port 1 • RS-232• Connection • 9-pin D-sub male connector• Communication speed • 1.2 to 19.2 kbaud• Modem type • Zyxel or others• Radio type • Niros 2001 (only the Niros 2001 protocol is supported)



Section 4

Section 4A Submersible Motors



SECTION 4: SUBMERSIBLE MOTORS

4A SUBMERSIBLE MOTORS

• Submersible Motor Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2• Submersible Motor Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5• Submersible Motor Mechanical Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6• Submersible Thrust Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8• Generator Use in Submersible Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10

4B SUBMERSIBLE MOTOR COOLING

• Required Cooling Flow and Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20• Water Temperature and Motor Derating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20• Motor Jacket/Shroud/Flow Inducer Sleeve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-22• Special Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-24

4C MOTOR INSULATION RESISTANCE

• Insulation Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-26• Dielectric Absorption Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-27

4D SUBMERSIBLE POWER CABLE

• Submersible Power Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-28• Cable Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-29

4-1


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Section 4A Submersible Motors4-2

4A SUBMERSIBLE MOTORSSubmersible Motors OverviewSubmersible motors are designed specifically for operation in and under water. The motor and power cable aredesigned and sealed to prevent water from contacting any part of the electrical circuit. In most cases, the motors isequipped with a high-capacity thrust bearing to support the total thrust of the pumping unit. The submersible motordepends on surrounding water to carry away heat; most require a specified flow of water for adequate cooling.Submersible motor construction can be categorized into three basic types.

Canned - Stator windings and connections in these motors are sealed in a metal enclosure. The rotating parts runin water.

Wet Windings - These motors are entirely water-filled, with windings and connections individually sealed fromwater by their insulation. Again, the rotating parts run in water.

Oil-Filled - These motors are entirely filled with oil. An enclosure protects them from water entry by joint seals anda shaft seal. Rotating parts run in oil.

Water-filled motors are normally sealed to prevent the entry of abrasives from well water; they may be factory-filledor require filling before installation. All three types of submersible motors use a flexible diaphragm to allow forthermal expansion and contraction of the internal liquid, and to equalize pressure inside and outside of the motorat any submergence.

Ratings. Motors are typically identified by the nominal size of the smallest well into which they may be installed.Thus a 6-inch motor has a diameter which provides necessary minimum clearance for installation in 6-inch andlarger wells, the same is true for other motor sizes. Electrical ratings, speeds, and types vary with motormanufacturers and their designs. Table 4-1 shows the approximate range of ratings available in various motor sizesand types. The table shows only two-pole motors which are most common in lower ratings, 3450 rpm nominal at60 hertz. Larger pumps may require slower speed, four-pole motors.

Motor Selection. Selecting the best submersible motor for a particular pump application requires carefulconsideration of several factors. The motor must match the pump in mounting dimensions, and must also haveadequate Hp load rating and thrust rating to support the pump over its entire operating range. Most 4”, 6”, and 8”submersible motor sizes are built to NEMA standards, which define their physical dimensions, electrical ratings, andthrust ratings. The motor must be capable of operation at the water temperature and velocity presented by theinstallation. Most motor nameplates and/or the manufacturer’s literature specify the maximum water temperatureand minimum required velocity past the motor. Motor operation in water that exceeds the rated temperature may beallowable at reduced loading, depending on the particular motor. NEMA standards are based on 25°C (77°F)maximum ambient water temperature. Some motors; however, may be rated for full output at 30°C (86°F) or higher.If the installation does not assure the specified velocity past the motor- because of well diameter, well inflow abovethe pump or other reasons - a sleeve over the motor should be used to induce the required velocity.

Types of Cable. Several cable manufacturers produce cable designed for use with submersible motors. The exacttype of cable to be used is usually specified by the pump manufacturer or selected by the installer. Cable may bethree individual conductors twisted, three conductors molded side by side in one flat cable, or three individualconductors sealed within a round overall jacket. The insulation around the conductor is typically type RW, RUW,TW or equivalent, and specifically suited for use under water. Stranded copper cable is universally preferred;however, aluminum conductors can be used. The selection charts shown in Table 4-18 are based on copper cable.

Motor Controls. Motor starters are relatively simple devices. They usually consist of a three-pole magneticallyoperated contactor, a current sensing device, and a control circuit. The current sensing device is used to trip thecontactor when the load amperes exceed a specified amount for to long a period. The contactor should be ratedbased on horsepower load. The control circuit can be operated either manually or automatically by using varioussensing devices such as; pressure switches, timers, liquid level controls, computers, and PLC’s, etc. The NationalElectrical Code (NEC) requires that motor starters always be connected in combination with fuses and a disconnectswitch, or with a circuit breaker on the source side. Such isolating device should be located within easy reach of


Section 4


anyone who wants to service the equipment. A positive power disconnect/ lock out device must be located nomore that 50’ (horizontal) from the well head.

All starters are provided with an overload relay to protect the motor from excessive heat. If the heat exceeds theamount the insulation can withstand, the motor’s normal life expectancy will be shortened. The characteristics ofsubmersible motors are different from standard air-cooled motors. Submersible motors are very heat-sensitive andrequire special overload protection. If the motor is stalled, the overload protector must trip within approximately 10seconds to protect the motor windings. Accepted protective components for submersible motors are three-leg,ambient-compensated thermal overload relays and quick-trip bimetal type heaters. Solid state overload protectivedevices such as the Grundfos CU3 device, can provide excellent protection and flexibility. Ambient temperaturecompensation for submersible motor protection is essential, since the motor is in a constant ambient (water) and theoverload is in a varying ambient.

The overload protection should be based on the manufacturer’s specification, or on the full load current ratingstated on the motor nameplate. Control manufacturers supply selection charts for overload protection for thispurpose. Electronic (solid state) overload relays which provide faster trip characteristics than bimetal overloadrelays. In making a choice between the thermal or electronic overload relays, the features of each type should beconsidered. See Section 3D for various electronic controls offered by Grundfos.

Lightning and Surge Protection. Submersible motors are more vulnerable to damage by lightning and voltagesurges, as they operate in a highly electrically conductive environment compared to surface motors. Lightningarrestors when properly selected and installed, can provide excellent surge protection. The need for a arrestors isgreater in pump installations that are distant from the primary power circuit, and in areas where electrical storms areknown to occur frequently. Power lines are subject to extremely high voltage surges caused by switching loads,harmonics and electrical storms. Surges also may be induced by charged clouds passing over the lines or bygenerator fluctuations. A properly selected and installed surge arrestor can provide protection against motordamage.

Power Supply. Adequacy of power lines, transformers and/or generators must be sized to ensure reliableoperation. Transformer and generator requirements are often provided by motor manufacturers or can be calculatedbased on load requirements. In some instances, the utility company may require power factor correction, to reducelosses and voltage drop in power lines by the addition of capacitor banks. Selected power supply issues arediscussed in Section 3A.

Motor Operation. All deep well submersible type pumps are powered by electric motors. The optimum powerunit used is dependent on several physical and environmental factors, which include the horsepower required forpumping, the annual hours of operation and the availability and cost of energy.

How does a motor “know” what horsepower to deliver? Electric motors draw power in proportion to the applied load.Although a motor is rated for a certain output power (this is the number stamped on the nameplate), that motorcan deliver a wide range of power depending on the voltage and frequency provided and the torque demanded bythe shaft load.

Power is the rate of energy use. Input power to a electrical motor is measured in kW, the motor converts thatelectric power into mechanical power. Output power is the product of speed (rpm) and torque (ft.-lb.). See Section3B for additional information regarding the speed torque relationship.

For a given voltage and frequency combination, the motor will always operate at a point on a specific torque vs.speed curve. The units of both output power and torque are generally specified as a percentage of the motors fullload rated value on the manufactures performance curve. A small change in speed produce large changes inavailable torque near the normal (close to rated) operating speed. Thus as load torque increases, the rotationalspeed will drop slightly (increased slip) as the motor load increases.

As soon as voltage is supplied to the motor, the motor “knows” the power to deliver by speeding up until it putsout exactly the same torque as the load requires at that speed. At start-up, the motor produces torque higher thanthe torque required by the driven load, accelerating the pump shaft to full load speed. A submersible pump is a

4-3


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4

centrifugal device which exhibits variable torque load characteristics, it takes very little torque to accelerate the loadat low speed. A centrifugal pump requires torque approximately proportional to the square of its speed; thisrelationship between torque and speed is illustrated in Figure 3-14.

The maximum speed of a induction motor is a function of the number of poles and line frequency. Typical speedsassociated with submersible motors, based on the number of poles and a line frequency of 60 Hz are; 2p - 3600rpm (sync.)/ 3450 rpm (@ full load) and 4p - 1800 rpm (sync.)/ 1760 (@ full load). The synchronous speed on anymotor can be calculated when the number of poles and operating frequency is known, using the formula below:

where; N = sync. speed (rpm), P = poles, f = frequency (Hz)

Note: Actual induction motor speed at full load will be 2-5% less than the synchronous speed calculated using theformula above.

A pump driven by two different motors of the same nominal speed (rpm), but different Hp ratings, will drawapproximately the same power. Under steady-state conditions the speed of operation does not change significantly,unless the motor is too small and stalls.

Motor Loading, Failure and Lifetime. Motor load is commonly expressed as the percentage of output power torated output. Because output power (load) is difficult to measure in the field, motor load is usually estimated bymeasuring input power (kWI) and assuming an efficiency. It can also be estimated by measuring kVA and assumingboth power factor and efficiency.

Failure of a motor occurs when insulation breaks down from heat and mechanical stresses. The temperature of thewindings are primarily dependent on the current (amps) draw through them and the ability of motor to dissipatethe heat generated to the ambient environment. The higher the temperature, the shorter the life. A 10°C rise canhalve motor life. Motor current draw increases with load; as a result, motors that operate outside established loadand temperature ratings, will operate fewer hours before failure.

The voltage supplied to the motor terminals have a significant impact on motor life. Motors are designed to operateat a utilization voltage level or range, which is generally lower than the electrical system distribution voltageprovided to the utility meter. Motors can operate within a range of voltages; but above a certain voltage, destructivearcing and insulation deterioration can occur. Conversely, as voltage drops, more current is needed to maintaintorque and power; so the motor runs hotter and its life is shortened. In addition to the overall voltage provided tothe motor, voltage unbalance must be considered. If the voltages on the three phases to the motor are not wellbalanced, one winding will carry more current and may over heat and fail. Refer to Section 3A for additionaldiscussions regarding power supply issues.

Most electrical utilities guarantees voltages to a +/-5 percent standard; for “480” service voltage will be between 456V and 504 V at the meter; for “240” service, the voltages must be between 228 V and 252 V. If a motor is damagedas a result of over or under voltage outside the service limits, the utility may be liable for damages. Because motorswill operate cooler with higher voltages, reasonable over voltage levels rarely causes problems. There are only smallvariations in power factor and efficiency near rated conditions, volt- amps for a particular load can be assumedconstant over the range of voltage guarantee by the utility.

The maximum continuous load sustained by a motor is indicated by the service factor. A motor with a service factorof 1.15 can maintain a 115% overload; provided voltages are at the rated level and well balanced and the insulationsystem can be maintained at or below rated temperature. The actual motor load percentage can be calculated usingthe formula listed below:

where; Em = motor efficiencyIHp = Input Horsepower

Motor design and economic criteria have forced motor manufactures to build less service factor (SF) into motors.The SF allows the motor to provide power under optimal conditions at the nameplate rated power times the SF. Atrated conditions, (ie. 100 Hp motor with a SF of 1.15 is designed to provide 115 HP under continuos load). A 1982


N = f x 120/P

% Motor Load = EM x IHp x 100Rated Hp


Section 4


survey of motor manufacturers showed six of seven respondents recommending loading at 100 percent of ratedpower or less while only one still suggests loading up to SF rating. For this reason, it is recommended that motorloading not exceed 100% of the nameplate horsepower rating. It is best to consider the SF as a contingency agenstover loading as a result of low voltage, current imbalance and/or adverse ambient conditions.

Motor Efficiency. An electric motor operates at a relatively constant efficiency and speed over a wide range ofloadings. Efficiency does not change significantly with age of the motor or the load applied to it. Motor efficiency ispractically constant at motor loads between 50 and 100%. Reducing motor size for the sake of energy conservation,as a result of efficiency increases associated with loading the motor closer to full magnetic saturation (100% load) isnot recommended. As a general rule, a bigger motor that is underloaded (down to 50 percent) is more efficiencythan a fully loaded smaller motor driving the same load. Submersible pump motors will have slightly lowerefficiencies than surface motor as a result of the compact design requirements and the need for internalcooling/lubricating fluid. Most submersible motors have an efficiency stamped on the nameplate. The average ornominal efficiency values associated with “canned/ hermetically sealed” type submersible motors are listed in Table 4-6.

Submersible Motor TypesThe three (3) basic submersible motor types used in the water supply industry are: (1) Wet Winding, (2)Hermetically Sealed, and (3) Oil Filled. The focus of this manual will be on the Hermetically Sealed type; however,a brief description of each motor type is presented as follows:

Wet Winding type. A Wet Winding Type motor is one in which the motor windings are directly in contact withthe water. This is accomplished by the use of a waterproof insulation, which individually seals each wire witha coating several times as thick as the coating on standard copper wire. Water inside the motor air gap andcoils act as a heat transfer device by circulating through the windings and transferring heat to the externalcasing. Dissipation of this heat occurs as well water flows over the external case. As is the case in allsubmersible types, the internal cooling medium (water based) is also used for bearing lubrication.

Wet winding motors are available in 6” through 12” sizes and are generally rewindable. These motors areavailable in 3600 and 1800 rpm speeds

Hermetically Sealed type. A hermetically sealed type motor utilizes windings of standard construction andinsulation thickness. The windings are encased and hermetically sealed within the external shell casing on theoutside and an internal tube or liner inside the bore. The hermetically sealed enclosure eliminates thepossibility of water leakage into the winding. Bearings are also lubricated by water and heat dissipation isaccomplished in the same manner as the wet winding motor, however, the internal motor fluid does notdirectly contact insulation. Hermetically sealing is generally accomplished by epoxy resin impregnationprocess. Motor sizes range from 4” to 10” sizes and are not rewindable. These motors are most often suppliedin the 2 pole-3600 rpm configuration.

Oil Filled type. The Oil Filled Type motor also utilizes windings of standard construction and insulationthickness suitable for the operating voltage.. The windings are treated with an oil resistant varnish to withstandconstant circulation of dielectric oil. A rotating shaft seal is necessary to keep the oil in and external water out.As in the Wet Winding type, the oil serves as a cooling medium with circulating oil transferring winding andbearing heat to the external case. Water flowing over the external surface dissipates this heat. The oil in thistype motor serves as the bearing lubricant.

Oil filled motors are available in sizes ranging from 4” to 18” and are rewindable. These motors are availablein 3600, 1800 and 1200 rpm speed. These motors can operate at higher temperatures than motors employing awater based motor fluid. Horsepowers range from 7.5 to 700 Hp.

The Petroleum Industry utilizes a special adaptation of the oil filled motor to produce high water cut oil well.These motors normally utilize a bolt-on seal section to prevent well fluid from entering the motor, operate at3600 rpm and can be wound for voltages up to 5kV.

4-5

Submersible motors are relatively long and slender because they must fit into well casings. The Hermetically Sealedmotor is the most common type used in the water supply industry. They are most frequently supplied configuredfor 3 phase-3600 rpm service; in 4”, 6” and 8” sizes with horsepower ranges from 5 Hp to 200 Hp. Single phase 4”motors in horsepower ranges from 1/3 to2 Hp are normally confined to residential/individual water supply needsand are not presented.

Submersible Motor Mechanical ComponentsThe mechanical construction of a submersible motor consists of four basic components:

1) Frame & Stator2) Upper Bracket3) Lower Bracket4) Rotor


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Figure 4-1: Major Submersible Motor Components

16

15

14

17

5

2

1

4

6

3

9

87

12

10

11

13

14

1 Stator Stainless 1.4301 304 1.4539 904L 1.4539 904Lsteel

2 Rotor Stainless 1.4057 431 1.4462 1.4462steel

3 Thrust bearing,lower

4 Radial bearing complete

5 Bearing pipe Cast ironcomplete GG20

6 Thrust bearing,upper

7 Clamping ring

8 Bearing retainer

9 Adjusting screw

10 Diaphragm NBR-rubber X XViton X

11 Motor End Stainless 1.4301 304 1.4539 904L 1.4539 904LShield steel

12 Nut (special)

13 Lock washer

14 Nut Stainless 1.4401 316 1.4539 904L 1.4539 904Lsteel

15 Staybolt Stainless 1.4401 316 1.4539 904L 1.4539 904Lsteel

16 Staybolt Stainless 1.4401 316 1.4539 904L 1.4539 904Lcomplete steel 1.4401 316 1.4401 316

17 O-ring

W.-Nr. AISI W.-Nr. AISI W.-Nr. AISIComponent Material

MS 4000 MS 4000 R MS 4000 REPos.no.


Section 4

Section 4A Submersible Motors 4-7

The frame and stator serves as a housing for the stator iron stack and winding assembly. Internal stainlesssteel construction is always required where water based motor fluids are used. External stainless steel claddingis recommended (normally provided as a standard) for water supply applications. Stainless Steel providesexcellent resistance to corrosive water and provides excellent life.

The upper bracket assembly houses the lead wire and plug connector (if applicable). Guide bearings, waterslinger, seals, and a filling water plug are required. The upper bracket also utilizes a NEMA flanged fit tocouple easily to a vertical turbine style pump.

The lower bracket assembly houses the thrust bearing assembly (Mitchell or Kingsbury type), diaphragm(pressure equalization), guide bearing, and drain plug.

The rotor assembly typically includes laminations pressed and held together by end rings; splined stainlesssteel shaft, and balancing disks. The ability to keep water from permeating the stator wire helps determine thereliability of a submersible motor. The ability to keep abrasive sand from the moving parts also greatly affectsits life.

Refer to Figure 4-1 for a pictorial presentation of the major submersible motor mechanical components. The actualmotor configuration will very from manufacture to manufacture.

Application and Selection Issues. The term application not only refers to the end use of the product but also theparameters which affect the selection of the correct submersible motor and pump products. The primaryconsiderations involved with the selection of submersible motors are discussed as follows:

The Insulation system. The insulation system is the key to long motor life. The life of the insulation system isaffected by three major factors: Load, Duty Cycle, and Temperature Rise. The load of a motor is described inhorsepower or kilowatts and is defined as the work required to perform a function. The load created bypumps is a result of the rotation of impeller(s) to create a pressure forcing fluid through a system. The dutycycle is the time period, which the motor is operating. It is continuous or intermittent. Temperature rise is thedifference between the operating temperature of the windings and the temperature of the medium to cool themotor. The rise of the motor is directly affected by the load and duty cycle. Extra load in the form of a servicefactor increases the temperature rise of the winding.

The total temperature must never exceed the maximum capacity of the insulation system. Submersible motorsused for water well service normally employ class “F” insulation (150°F rise), but are designed for a class Atemperature rise (60°F).

Cooling. Submersible motors are no different than conventional motors, in that the heat generated within themotor must be dissipated. The temperature rise within the motor is limited to a value which when added tothe temperature of the external cooling medium does not exceed the maximum temperature capacity of theinsulation system. The ability to dissipate the heat depends on two factors: (1) The temperature of the coolingmedium (ambient) and (2) the rate of cooling medium flow past the motor external surfaces. Excess ambienttemperature and reduced flow rate both require derating of the load capability of the unit. The derating of theload reduces the temperature rise of the winding within the limits set by the heat dissipation capacity of thecooling medium.

Materials of Construction. Submersible pumps and motors are also selected based on the chemical andphysical make-up of the water in which they will be submerged. Sea water applications require specializedconstruction due to the corrosive water encountered. A standard motor will not survive highly corrosive watersubmergence, while a specially designed motor will.

Design Factors. Other factors, which affect submersible motor selection, are voltage, depth of installation,thrust and controls. It is necessary that the voltage and frequency variations be within the limits set in NEMAMGI-18 (submersible motors for deep well pumps). The maximum recommended depth for most submersiblemotor relates to 290 psi on the unit (approx. 2000 feet). The thrust delivered by the pump must be less thanthe capacity of the thrust bearing of the submersible motor. Controls must be quick trip, ambient compensatedtype to quickly pull an improperly applied or defective motor off the line so that no damage occurs.


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Submersible construction and design for 4”, 6” and 8” sizes are covered by NEMA standards. There are presently noNEMA standard governing 10” and 12” motors. Pump/motor attachment (connection) issues such as shaft stick-up,shaft diameter, bolting pattern adapters and fastener requirements for 10” and 12” motors must be considered toinsure the pump-motor compatibility.

Submersible Motor Mounting Position. The published motor manufacture guidelines should be followed withregard to motor orientation form the vertical. Some manufacturers allow only minimal variance from the vertical,while others will allow a mounting position ranging from vertical shaft up to horizontal, with minimal stipulations.The submersible pump end is relatively unaffected by orientation.

Submersible Thrust Bearings. All submersible pumps require a thrust bearing to support the unbalanced hydraulic thrust load (typically downthrust) and the rotating element weight (impellers and pump shaft). The bearing is typically mounted within themotor and is located in the lower portion of the motor housing. The thrust bearing size/rating is a function of pumpspeed, thrust load and required bearing life. Thrust bearings fall into one of two general classes, anti-friction (ball orroller) and plate (tilting or fixed). Only the plate type bearings have applicability in the submersible industry, asthey are compact and have thrust load carrying capability. Plate type bearings are often referred to as “Kingsbury”or Michell” bearings. Other common names, which describe the operation of the bearings include tilting shoe, pivotshoe, tilting pad or solid shoe.

The canned/ hermetically sealed motor is the most common submersible motor type used in the water supplyindustry. Motor fluid is typically water, which has low viscosity and excellent lubrication properties. The platetype/tilting shoe thrust bearing design is most commonly used in the canned/ hermetically sealed motor consists ofa group of thrust pads mounted in a stationary retainer and a rotating thrust disc (plate). The thrust pads pivot (tilt)individually, allowing for the entire bearing assembly to be self leveling and aligning. The construction allows eachthrust pad to be loaded equally. Submersible motor bearing problems are rare and are not a significant applicationconsideration under normal circumstances. High head and/or temperature duty should warrant a check of thrustbearing capacity and limits.

The viscous drag created by the rotation of the thrust disc, draws water under the pads making them tilt. The loadis supported by the formation a lubricating water wedge which develops between the tilted bearing pads and disc.The low viscosity (drag) of water results in minimal friction and negligible wear. Plate type bearings have atheoretically infinite life, as long as the lubricating film is maintained between the plate and the pads. However, thistype bearing should not be overloaded as failure will result if the lubricating film is lost. The size of the bearingmust be adequate to carry the maximum thrust which could be imposed on it by the pump. This normally occurswhen the pump is operated with a closed valve. The lubricating film may be lost during the long idle periods orduring prolong operation at low speed.

Radial Bearings. Submersible pumps employ sleeve type bearings to maintain rotor alignment. A electro-graphiticmaterial is used in there construction. They run with extremely low (negligible) friction as they are submerged in

the motor cooling/lubrication fluidat all times.

Thrust Bearing Ratings. Minimummotor thrust requirement for 4, 6and 8 inch motors are specified byNEMA standards, for “SubmersibleMotors for Deep Well Pumps”. TheNEMA standard ratings are adequatefor a vast majority of submersibleapplications; however, most motormanufactures offer a variety ofrating which exceed the NEMAminimums. Table 4-1 list typicalthrust data offering by motor sizeand nominal horsepower.


Table 4-1: Typical Submersible Motor Thrust Data (2 pole-60Hz)

Motor Size Horsepower Thrust Ratings – (lbs.)

(nominal – in.) Range (Hp) Typical NEMA Min.

4 1/3 - 3/4 300 - 500 –1 - 2 500 - 750 –3 - 10 1000 - 1500 –

6 5 - 7.5 1000 - 1500 500 - 75010 - 40 3300 - 3500 1000 - 300050 - 60 6000 3000 - 6000

8 40 - 1000 10,000 4,000 - 10,000125 - 200 10,000 10,000

10 150 - 250 13,400 No. Std.

Bearing Life. The life of an anti-friction thrust bearing is shortened if the thrust load is increased beyond its rating.Standard life expectancies for each size bearing have been established by the bearing manufacturers so that theproper size bearing can be selected.

The average life of a bearing is equal to the number of hours or years of continuos operation when 50% of all thebearings operating under identical conditions and rated load have failed. For example, if 100 identical bearings wereplaced in service under identical operating conditions and after 5 years, 50 failures had occurred, the average life ofthat bearing would be 5 years.

The minimum life of a bearing is equal to the number of hours or years of continuous operation when 10% of allthe bearings operating under identical conditions and rated load have failed. The minimum, or as it is morecommonly called, the L-10 life, is the life expectancy which is normally used in specifications. The pump motorindustries have standardized on thrust bearings having a minimum life of one year (8760 hours) which is also equalto an average life of 5 years (43,800 hours). Thus the purchaser of a pump who anticipated operating the unit for 8hours a day during 4 moths of the year could expect a minimum bearing life of 9 years (8760/4 mo. x 8 hr/day x30 day/mo. = 9.12 yr) or an average bearing life of 45 years (43,800/960 hr/yr), based on this amount of usage.

AWWA standards specify the submersible motor thrust bearing have ample capacity to carry the maximum thrustload (static & dynamic) of the pump. The thrust bearing must have a L-10 life of 8800 hours (8760 hours rounded)at the specified thrust rating in accordance with AFBMA (Anti-Friction Bearing Manufactures Association)requirements. In addition, AWWA specification require the submersible system provide provisions for handlingmomentary up-thrust either in the pump and/or the motor.

Thrust Bearing Special Considerations. The enemies of the plate type (tilting shoe) thrust bearings are; (1) heat -reduced viscosity, (2) misalignment - rarely a problem, (3) foreign particles and (4) vibration. Vibration,misalignment (from defective shoes) and/or long period of no use can cause a disruption of bearing lubricatingfilm, which allows destructive metal to metal contact.

The operation of submersible pumps controlled through a variable frequency drive (VFD) can create thrust bearingproblems. At low speeds frequency below 30 Hz, thrust bearing lubrication can be lost or impaired. Long durationoperation at low frequency (low speed) is likely to damage the thrust bearing leading to premature motor failure. Inorder to mitigate the affect of slow speed/low frequency operation, the motor should not be operated below 30 Hzexcept as required for start-up and shut down ramp.

Submersible Pump/ Motor Thrust Losses. Thrust bearing power losses associated with 2 pole - 60 Hz (3450rpm) submersible motors are typically in the range of 10 watts per 100 lbs. of thrust. Figure 4-2 below can be usedto estimate power losses in 6 through 12 inch, 2 pole submersible motors.


Section 4


Figure 4-2: Submersible Motor Thrust Loss (2 pole - 60 Hz motors)

Thrust Load in pounds - Horizontal axis / Loss in Watts - Vertical axis


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Shaft Deflection. Themotor shaft willdeflect within theelastic limits of themotor shaft materialunder load. Thedeflection reducesmotor stick-up heightas load is applied.Submersible pumpaxial clearances are

designed to allow for compressive (downward) elastic compression. Typical deflection values based on motor sizeand thrust bearing rating are listed in Table 4-2.

Generator Use in Submersible ApplicationsWhere utility power is not available or has failed, or the submersible pumping system is to be portable; a enginedriven generator is used to provide the pumping power requirements. In the generator selection process severalfactors must be considered, selection factors include but are not limited to; load type (motor, linear, non-linear)humidity, temperature, altitude, starting method, etc. Table 4-3 lists conservative generator sizes; for three and singlephase submersible motor applications. The generator manufacture should be consulted for selection of all largethree phase generators.


Table 4-2: Typical Submersible Motor Shaft Deflection

Motor Type, Bearing Rating Rate of Deflection Total Deflection @ Rated Thrust

4”, 300 lb. .002” per 100 lb .006” at 300 lb.4”, 400 lb. .002” per 100 lb. .008” at 400 lb.4”, 900 lb. .0005” per 100 lb. .0045” at 900 lb.6”, 150 lb. .0005” per 100 lb. .0075” at 1500 lb.

6”, 3500 lb. thur 30 HP .004” per 1000 lb. .014” at 3500 lb.6”, 3500 lb. 40 & 50 HP .006” per 1000 lb. .021” at 3500 lb.

8”, 10,000 lb. .002” at 10, 000 lb. .020” at 10,000 lb.

Table 4-3: General Engine Driven Generator Set Sizing

Motor Hp Minimum Rating of Generator

Externally Regulated Internally Regulated

kW kVA kW kVA

1/3 1.5 1.9 1.2 1.51/2 2.0 2.5 1.5 1.93/4 3.0 3.8 2.0 2.5

1 4.0 5.0 2.5 3.1251-1/2 5.0 6.25 3.0 3.8

2 7.5 9.4 4.0 5.03 10.0 12.5 5.0 6.255 15.0 18.75 7.5 9.4

7-1/2 20.0 25.0 10.0 12.510 30.0 37.5 15.0 18.815 40.0 50.0 20.0 25.020 60.0 75.0 25.0 31.0

25 75.0 94.0 30.0 37.530 100.0 125.0 40.0 50.040 100.0 125.0 50.0 62.550 150.0 188.0 60.0 75.0

60 175.0 220.0 75.0 94.075 250.0 313.0 100.0 125.0100 300.0 375.0 150.0 188.0125 375.0 469.0 175.0 219.0175 525.0 656.0 250.0 313.0200 600.0 750.0 275.0 344.0

Note: 1. To insure starting of two-wire single phase motor, the minimum generator rating should be 50% higherthan the tabulated values.

2. Tabulated values are based on a typical 80°C temperature rise for a generator operating at continuousduty with 35% maximum voltage dip when the motor is started Across-the-line (ATL). Ratings based on a30°C (86°F) ambient temp. @ sea level.

A minimum motor terminal voltage of 65% during start-up is generally adequate to start three phase and singlephase - 3 wire motors. The lower the start-up voltage dip, the easier it is to start the motor. The 35% maximumallowable voltage dip (100% - 65% = 35%) takes into account instantaneous cable voltage drop at start-up. Cablevoltage drop can be 4-7 times the nominal running value at start-up; which is particularly important for deepsettings. Motor undervoltage and overcurrent protection should be designed to accommodate the short durationinduction motor/genset - low voltage/high current start-up phenomena.

Generator frequency is important to maintain at the level required/dictated by the motor design, and is a function ofgenerator speed. Motor speed varies with the output frequency of the generator. When the output frequency doesnot match the motor rating. Pump performance will vary from the published data as predicted by the affinity laws.A pump running at 1 to 2 Hz below motor nameplate frequency will not meet its performance curve. Conversely, apump running at 1 - 2 Hz above may trip overloads.

Generator Derating. The generator manufacturer’s recommendations for derating should be followed whenavailable. In theabsences of suchdata, the deratingfactors specified inTable 4-4 may beapplied withreasonable accuracy.

Types ofGenerators.Generator arenormally classified on

the basis of the type of voltage regulation and excitation. The two principal types are internally and externallyregulated. The externally regulated type is most commonly encountered in low power application and voltages lessthan 300V, as they are generally less expensive.

Voltage Regulation & Excitation. The function of the voltage regulator is to monitor and correct generator outputvoltage by controlling excitation current to the rotor; in response to changes in output current (load), power factorand speed.

The term excitation, as applied to a.c. generators, refers to the source of power used to provide the rotor currentrequired to establish the rotating magnetic field within the generator. Changes in the rotor/ excitation current isrequired to maintain the correct generator out put voltage. The amount of excitation current provided to the rotor iscontrolled through the voltage regulator. Self excited generators derive there excitation power from generator outputterminals. Separately excited generator derive field power from a external or isolated source, such as a permanentmagnet generator (PMG).

1. Internally regulated (IR) generators have an additional winding in the generator stator that is used to immediatelysense changes in output current and automatically decrease/increase output voltage in response to load changes.IR generators are self excited and generally provide better regulation than externally regulated units in smallerpower plants.

2. Externally regulated (ER) generators use a externally mounted voltage regulator that senses generator outputvoltage. As the voltage dips at motor start-up, the regulator increases the output voltage of the generator. ERgenerators can be self or separately excited. ER generators which employ self excitation are generally 25-50%larger with respect to kW/kVA rating in order to deliver the same starting torque as an IR generator. Separatelyexcited ER generator can provide equivalent performance to IR generator but are generally available in largersizes.

Special Generator Control and Starting Considerations. The values listed in Table 4-3 under the heading ofexternally regulated, can sometimes be reduced if a “Reduced In-Rush” starter is used. Reducing the inrush currentwill reduce start-up voltage dip, which in turn may allow for the use of a generator as much as 20% smaller than


Section 4


Table 4-4: Typical Generator Power Derating Factors

Fuel Type Altitude Temperature

Diesel 3.5% per 1000’ ASL 2% per 10°F above 86°FDiesel (Turbo) 2.5% per 1000’ ASL 3% per 10°F above 86°F

Gasoline 2.5% per 1000’ ASL 5% per 10°F above 104°F

Notes: 1. Reduce power output for diesel generators 6% for 100% RH2. 30°C = 86°F, 40°C = 104°F, (5°C) = (10°F), ASL = Above Sea Level, RH = rel.

humidity

specified in Table 4-3. Regardless of the starting method, the generator minimum size should be sufficient toprovide the entire submersible pump load and required auxiliary equipment. Derating should be applied asapplicable.

The use of a reduced voltage/in-rush starters is recommended any time motor horsepower exceeds 25 Hp, as it willreduce generator stress, size and improve starting of deep set units. Common submersible motor reduced in-rushstarting methods employed in the U.S. are; auto transformer (AF), soft start (SS) and variable frequency drive (VFD).Each starting method is discussed in greater detail in Section 3C. VFD /generator performance is discussed below,as it is not always possible to reduce generator size under non-linear load conditions, which a VFD presents.

Generator Performance with Variable Frequency Drives (VFD’s). Submersibles controlled through VFD’s can createproblems for generators. VFD’s create waveform distortion (spikes, notching, ringing, etc.) which can makegenerator voltage regulation and performance erratic. In general, generators which are internally regulated - selfexcited or externally regulated separately excited provide the best performance under non-linear load/VFD serviceconditions. Specific generator features and application considerations which have proven affective are:

1. Solid state voltage regulator in lieu of electro - mechanical voltage build-up relay types.2. Three phase generators which employ voltage sensing on all three output terminals perform better than single

leg monitoring, as the affects of wareform distortion are minimized by providing an average of all 3 legs at anyinstant.

3. Employ manufacture recommended EMI/RF voltage regulator filters.4. Oversize the generator by 25% to 50% based on peak load. Under no circumstances should the VFD/submersible

system maximum power requirement exceed the genset prime power output capability.5. Attenuate VFD feedback harmonic through the use of a isolation transformer or line reactors when practical.

Diesel Generator Sets. Generator sets are often rated in terms of prime and standby (peak) continuos outputpower. The prime power rating reference the maximum efficiency of the generating plant, which occurs when thediesel engine is loaded to approximately 70 -80% of its maximum load. The prime power rating provides the lowestfuel consumption per kW output. The standby power rating represents the maximum power output capability of thegenerating plant when the engine is loaded to 100%.

When the generator is the primary power source for a permanent installation, the generator should be sized to meetthe total system requirements based on its prime power rating. When the generator is a secondary (back-up/emergency) or portable power supply, it may be acceptable to select the generator based on a standby power basis.Other selection factors such as; load type, allowable voltage dip and regulation method, ambient conditions, etc. -

must be applied first toobtain the target powerrequirement. A single linediagram of a typicalemergency power systeminstallation is shown inFigure 4-3.

Generator Operation.Always start the generatorbefore the motor is started,and always stop the motorbefore the generator isstopped. The motor thrustbearing may be damaged ifthe generator is allowed tocoast down with the motorconnected. Non-disconnected stopstypically occur whengenerators are allowed torun out of fuel.


Sect

ion

4


Figure 4-3: Typical Emergency Power System

EmergencyLoad

Non-emergencyLoad

TransferSwitch

OvercurrentProtection

MainDisconnect

OvercurrentProtection Submersible Pump

Starter/Controller

Pumping Plant Aux.

Utility or NormalPower Source G Genset

P


Section 4


Table 4-5: Typical 4” Submersible Motor Physical Data (Grundfos MS402)

4” Single Phase ~ 3W ~ 2P - 60Hz

Hp “L” Shipping Wt. Thrust Shaft Ht.

(in.) (lbs.) (lbs.) (in.)

1/3 10.2 17.4

1/2 11.0 19.4

3/4 11.6 19.8 900 1.5

1 12.2 22.9

1-1/2 13.7 26.4

2 13.7 27.6

4” Three Phase ~ 3W ~ 2P - 60Hz

1/2 9.0 14.3

3/4 9.6 16.1

1 11.0 19.4 900 1.5

1-1/2 12.2 22.9

2 13.7 26.4

3 13.7 29.5

"L"SEE

TABLE

∅ 3.74

1.484

1.5081.498

.146

.90





3 18.0 37.5

5 22.7 48.5 1500 1.5

7-1/2 26.6 59.5

10 30.6 130.0

Industrial Motors

2 18.0 37.5

3 19.5 48.5 1500 1.5

5 26.6 59.5

7-1/2 30.6 130.0

1.5081.498

.157.866

∅ 3.74

"L"SEE

TABLE


Sect

ion

4






7-1/2 21.4 80.4

10 22.6 88.2

15 25.0 109.1

20 27.5 124.5 4400 2.875

25 29.7 136.6

30 32.0 149.9

35 34.4 162.0

40 37.2 179.6

Industrial Motors

7-1/2 23.8 100.3

10 25.0 109.1

15 27.5 124.5 4400 2.875

20 32.0 149.9

25 34.4 162.0

30 37.2 179.6

"L"SEE

TABLE

∅ 5.44

2.8752.869

.2361.181


Section 4


Table 4-5: Typical 4” - 10” Submersible Motor Physical Data (Franklin Motor)




1/3 8.78 16

1/2 9.53 18 300 1.5

3/4 10.66 21

1 11.75 24

1-1/2 13.62 29 650

2 15.12 32

3 23.62 55 1500

5 29.62 70


3 20.62 44

5 23.62 55 1500 1.5

7-1/2 29.62 70

10 43.89 120




5 25.4 112 1500 2.875

7-1/2 28.00 124

10 30.56 140 3500

15 33.13 154


5 22.88 98 1500 2.875

7-1/2 24.19 106

10 25.44 114

15 28.00 128

20 30.56 142 3500

25 33.13 154

30 35.69 168

40 40.81 202

50 55.31 300 6000

60 61.31 330


Sect

ion

4


Table 4-5: Typical 4” - 10” Submersible Motor Physical Data (Franklin Motor) (continued)




40 35.8 310

50 38.8 350

60 41.8 385

75 54.9 424

100 58.9 469 10,000 4

125 68.8 700

150 77.8 850

175 85.8 960

200 94.8 1050




150 59 860

175 63 950 13,400 4

200 68 1010

250 76 1150

Notes: 1. 4”, 6” and 8” motor general mechanical, physical and electrical characteristics are governed by NEMAstandards for “Submersible Motors for Deep Well Pumps”.

2. Motors configured for WYE - DELTA (Y-D) starting have the same overall dimensional characteristic asthe Across-the-Line (ATL) units listed above.

3. 2W ~ 1 ph motor have the same dimension and 3W - 1 ph motors.


Section 4


Tab

le 4

-6:

Typ

ica

l S

ub

me

rsib

le M

oto

r P

erf

orm

an

ce

Ch

ara

cte

rist

ics

(He

rme

tic

ally

Se

ale

d /C

an

ne

d T

ype

~ 2

po

le ~

60

Hz)

Mo

tor

F.L.

Rat

ing

S.F.

Rat

ing

Eff

icie

ncy

%P

ow

er F

acto

r %

L.R

.A./

Ckt

. Brk

./Fu

seN

EMA

Size

/Typ

eH

pV

olt

sS.

F.A

mp

sK

wA

mp

sk

WS.

F.F.

L.3/4

S.F.

F.L.

3/4

L.R

.A.

kVA

co

de

Std

.D

elay

Star

ter

1/3

115

1.75

8.0

0.48

9.2

0.72

60.0

51.0

44.8

71.0

53.5

46.5

34.8

N25

100

230

4.0

4.6

17.2

155

001/

211

51.

6010

.00.

6812

.00.

9761

.555

.048

.872

.557

.549

.750

.5M

3015

023

05.

06.

023

.015

700

3/4

230

1.50

6.8

0.95

8.0

1.33

63.5

59.0

53.2

74.0

61.5

53.2

34.2

M20

91

230

1.40

8.2

1.20

9.8

1.60

65.0

62.2

57.4

74.0

62.5

53.5

41.8

L25

120

1 1/

223

01.

3010

.01.

7011

.52.

1567

.966

.062

.081

.474

.466

.152

.0J

3015

223

01.

2510

.02.

1013

.22.

6570

.071

.068

.893

.190

.586

.751

.0G

3015

323

01.

1514

.03.

1517

.03.

6570

.971

.869

.698

.097

.596

.082

.0G

4520

15

230

1.15

23.0

5.10

27.5

5.90

71.1

71.9

70.0

97.5

96.4

94.0

121.

0F

7030

220

002

.83.

417

.3N

105

1/2

230

1.6

2.4

0.8

2.9

0.86

69.5

63.7

58.2

75.8

61.0

52.5

15.0

84

460

1.2

1.5

7.5

42

200

3.6

4.4

24.6

126

3/4

230

1.5

3.1

0.81

3.8

1.15

73.2

69.2

64.6

78.2

66.0

57.2

21.4

N11

546

01.

61.

910

.75

320

04.

55.

431

.015

61

230

1.4

3.9

1.07

4.7

1.44

72.5

70.0

66.0

79.4

69.0

60.0

27.0

M12

646

02.

02.

413

.56

320

05.

86.

838

.120

81

1/2

230

1.3

5.0

1.46

5.9

1.89

77.0

76.4

74.1

81.6

73.4

63.7

33.1

K15

746

02.

53.

016

.68

420

07.

79.

353

.625

100

223

01.

256.

72.

158.

12.

7069

.569

.567

.484

.479

.071

.246

.6L

2010

460

3.4

4.1

23.3

155

0020

010

.912

.571

3515

03

230

1.15

9.5

2.98

10.9

3.42

75.5

75.2

73.2

81.5

77.8

69.5

62K

3012

460

4.8

5.5

3115

620

018

.320

.512

250

251

523

01.

1515

.95.

0517

.85.

8174

.074

.072

.284

.081

.073

.010

6K

4520

460

8.0

8.9

5325

100

575

6.4

7.1

4320

820

026

.530

.518

880

352

7 1/

223

023

.026

.48.

4576

.276

.074

.083

.280

.072

.216

4K

7030

460

11.5

13.2

8235

1557

59.

210

.665

3012

110

460

1.15

17.0

10.0

18.8

11.1

75.2

74.5

72.0

79.2

75.5

67.1

116

K50

2557

513

.615

.093

4020

4”

- 3W

3 p

h3450

rpm

4”

- 3W

1 p

h3450

rpm


Sect

ion

4


Tab

le 4

-6:

Typ

ica

l S

ub

me

rsib

le M

oto

r P

erf

orm

an

ce

Ch

ara

cte

rist

ics

(He

rme

tic

ally

Se

ale

d /C

an

ne

d T

ype

~ 2

po

le ~

60

Hz)

(c

on

tin

ue

d)

Mo

tor

F.L.

Rat

ing

S.F.

Rat

ing

Eff

icie

ncy

%P

ow

er F

acto

r %

L.R

.A./

Ckt

. Brk

./Fu

seN

EMA

Size

/Typ

eH

pV

olt

sS.

F.A

mp

sK

wA

mp

sk

WS.

F.F.

L.3/4

S.F.

F.L.

3/4

L.R

.A.

kVA

co

de

Std

.D

elay

Star

ter

1/3

115

1.75

8.0

0.48

9.2

0.72

60.0

51.0

44.8

71.0

53.5

46.5

34.8

N25

100

230

4.0

4.6

17.2

155

001/

211

51.

6010

.00.

6812

.00.

9761

.555

.048

.872

.557

.549

.750

.5M

3015

023

05.

06.

023

.015

700

3/4

230

1.50

6.8

0.95

8.0

1.33

63.5

59.0

53.2

74.0

61.5

53.2

34.2

M20

91

230

1.40

8.2

1.20

9.8

1.60

65.0

62.2

57.4

74.0

62.5

53.5

41.8

L25

120

1 1/

223

01.

3010

.01.

7011

.52.

1567

.966

.062

.081

.474

.466

.152

.0J

3015

223

01.

2510

.02.

1013

.22.

6570

.071

.068

.893

.190

.586

.751

.0G

3015

323

01.

1514

.03.

1517

.03.

6570

.971

.869

.698

.097

.596

.082

.0G

4520

15

230

1.15

23.0

5.10

27.5

5.90

71.1

71.9

70.0

97.5

96.4

94.0

121.

0F

7030

220

002

.83.

417

.3N

105

1/2

230

1.6

2.4

0.8

2.9

0.86

69.5

63.7

58.2

75.8

61.0

52.5

15.0

84

460

1.2

1.5

7.5

42

200

3.6

4.4

24.6

126

3/4

230

1.5

3.1

0.81

3.8

1.15

73.2

69.2

64.6

78.2

66.0

57.2

21.4

N11

546

01.

61.

910

.75

320

04.

55.

431

.015

61

230

1.4

3.9

1.07

4.7

1.44

72.5

70.0

66.0

79.4

69.0

60.0

27.0

M12

646

02.

02.

413

.56

320

05.

86.

838

.120

81

1/2

230

1.3

5.0

1.46

5.9

1.89

77.0

76.4

74.1

81.6

73.4

63.7

33.1

K15

746

02.

53.

016

.68

420

07.

79.

353

.625

100

223

01.

256.

72.

158.

12.

7069

.569

.567

.484

.479

.071

.246

.6L

2010

460

3.4

4.1

23.3

155

0020

010

.912

.571

3515

03

230

1.15

9.5

2.98

10.9

3.42

75.5

75.2

73.2

81.5

77.8

69.5

62K

3012

460

4.8

5.5

3115

620

018

.320

.512

250

251

523

01.

1515

.95.

0517

.85.

8174

.074

.072

.284

.081

.073

.010

6K

4520

460

8.0

8.9

5325

100

575

6.4

7.1

4320

820

026

.530

.518

880

352

7 1/

223

023

.026

.48.

4576

.276

.074

.083

.280

.072

.216

4K

7030

460

11.5

13.2

8235

1557

59.

210

.665

3012

110

460

1.15

17.0

10.0

18.8

11.1

75.2

74.5

72.0

79.2

75.5

67.1

116

K50

2557

513

.615

.093

4020

4”

- 3W

3 p

h3450

rpm

4”

- 3W

1 p

h3450

rpm


Section 4


Tab

le 4

-6:

Typ

ica

l S

ub

me

rsib

le M

oto

r P

erf

orm

an

ce

Ch

ara

cte

rist

ics

(He

rme

tic

ally

Se

ale

d /C

an

ne

d T

ype

~ 2

po

le ~

60

Hz)

(co

nti

nu

ed

)

Mo

tor

F.L.

Rat

ing

S.F.

Rat

ing

Eff

icie

ncy

%P

ow

er F

acto

r %

L.R

.A./

Ckt

. Brk

./Fu

seN

EMA

Size

/Typ

eH

pV

olt

sS.

F.A

mp

sK

wA

mp

sk

WS.

F.F.

L.3/4

S.F.

F.L.

3/4

L.R

.A.

kVA

co

de

Std

.D

elay

Star

ter

4046

01.

1553

35.0

6040

.086

.286

.184

.886

.184

.278

.540

7K

175

7057

542

4886

.085

.984

.686

.085

.081

.032

612

560

350

460

1.15

6543

.073

49.0

87.3

87.2

86.2

86.6

85.5

80.5

528

K20

080

575

5360

86.6

86.5

85.2

87.0

86.0

86.0

422

150

7060

460

1.15

7952

.089

60.0

87.6

87.5

87.2

87.6

85.9

81.3

658

K22

510

057

561

6987

.387

.286

.186

.085

.080

.052

617

580

475

460

1.15

9764

.010

773

.588

.188

.086

.888

.086

.882

.083

3K

300

125

575

7885

87.5

87.4

86.2

86.0

85.0

81.0

666

225

100

100

460

1.15

125

85.0

144

97.5

88.3

88.1

87.5

88.1

86.6

81.7

1212

L40

017

55

575

104

116

88.0

87.8

86.4

85.8

84.0

79.0

970

300

150

412

546

01.

1516

510

9.0

189

125.

087

.386

.985

.387

.286

.977

.913

18K

500

225

575

136

150

87.2

86.9

85.3

84.3

82.6

77.5

1054

400

175

150

460

1.15

193

128.

022

114

6.0

87.7

87.4

86.0

86.0

84.4

79.7

1620

K60

025

05

575

154

177

87.9

87.4

85.7

82.9

80.8

75.0

1296

450

200

175

460

1.15

218

150.

025

017

3.0

87.3

87.0

86.7

88.8

87.6

84.8

1645

J70

030

057

517

420

088

.588

.086

.186

.285

.080

.013

1670

030

020

046

01.

1524

516

9.0

286

194.

088

.087

.986

.888

.788

.484

.518

75J

800

350

657

519

622

988

.088

.087

.089

.588

.685

.315

0060

030

015

046

01.

1519

511

0.0

130.

088

.083

.088

.088

.010

60G

600

250

575

517

546

01.

1523

013

0.0

150.

089

.088

.080

.074

.0G

800

350

575

200

460

1.15

250

150.

017

5.0

87.2

86.0

87.0

83.0

1260

F6

575

525

046

01.

1531

018

.50

215.

086

.589

.085

.082

.015

00E

900

450

657

5

10”

- 3W

3 p

h3525

rpm

8”

- 3W

3 p

h3525

rpm

Mo

tor

F.L.

A.

L.R

.A.

Eff

icie

ncy

Pow

er F

acto

r %

Size

/Typ

eH

pV

olt

sA

MP

S.A

MP

S.3/4

F.L.

3/4

F.L.

150

39.0

205

90.0

90.5

76.5

80.5

200

52.0

255

90.0

90.5

76.5

80.5

250

64.0

325

90.0

91.0

76.5

80.5

300

2300

77.0

400

90.0

91.0

76.5

80.5

350

89.0

400

90.0

91.0

78.0

80.5

400

102

490

90.5

91.5

76.5

80.0

450

113

490

90.5

91.5

78.0

81.5

500

125

540

90.5

91.5

78.0

81.5

12”

- 3W

3p

4P

1770

rpm

NO

TES:

1.M

oto

r si

ze/t

ype

refe

rs to the

smal

lest

pip

e I.D

. in

whic

h the

moto

r w

ill f

it2.

All

moto

rs a

re s

ingl

e vo

ltage

, th

ree

lead

s only

. Si

x le

ad Y

-Del

ta s

tart m

oto

rhav

e th

e sa

me

runnin

g per

form

ance

.3

Moto

r ra

tings

are

bas

ed o

n a

am

bie

nt te

mper

ature

of

86°F

(30

°C)

or

less

.4.

All

per

form

ance

dat

a is

bas

ed o

n a

vera

ge m

oto

r dat

a from

sev

eral

subm

ersi

ble

moto

r m

anufa

cture

rs.


Sect

ion

4

Section 4B Submersible Motor Cooling4-20

4B SUBMERSIBLE MOTOR COOLINGThe key to long submersible motor life is good cooling. Most submersible pumps rely on moving heat away fromthe motor by forced convection. The ambient/produced fluid is typically drawn by the motor in the course ofpumping to accomplish this task. Submersible motors used in the water supply industry are typically designed tooperate at full load in water up to 30°C (86°F), provided the flow velocity can be maintained at a minimum of 0.5feet per second (fps).

Required Cooling Flow and VelocityAWWA specifications state the maximum motor diameter and the minimum inside diameter of the well shall be insuch relationship that under any operating condition the water velocity past the motor shall not exceed 12 fps (3.7m/s) nor be less than 0.5 fps (0.15 m/s). The AWWA specification are principally applicable to motors 6-inch andlarger, as most 4-inch motor designs are based on a minimum cooling flow velocity of 0.25 fps (0.08 m/s) at ratedambient temperature. Table 4-7 relates flow, casing and motor size requirements to accomplish minimum coolingvelocity.

Table 4-7: Minimum Submersible Cooling Flow Requirements

Casing/Sleeve 4” Motor 6” Motor 8” Motor 10” Motor 12” MotorI.D. (inches) (0.25 fps) (0.5 fps) (0.5 fps) (0.5 fps) (0.5 fps)

(gpm)

4 1.2 – – – –5 7.0 – – – –6 13 9 – – –7 20 25 – – –8 30 45 10 – –10 50 90 55 – –12 80 140 110 78 –14 110 200 170 140 11016 150 280 245 213 18518 – 380 335 300 260

Notes: 1. Minor irregularities associated with motor shape and diameter variations between manufactures are notaccounted for in the table.

2. At the velocity specified in the table the temperature differential between the motor surface andambient water will range from 5° - 15°C (10-30°F).

Some submersible motor manufactures require no cooling fluid flow past the motor, when the produced fluidtemperature is 20°C (68°F) or less. Cooling by free convection in such cases, is only permitted in the verticalposition and is contingent on no adverse operating conditions present such as; poor power, high stop/startfrequency, presence of incrustating deposits on the motor surface, etc. Detramental operating conditions are difficultto identify or predict, and for this reason, the minimum cooling flow should be provided whenever possible -regardless of the ambient fluid temperature.

Water Temperature and Motor DeratingAs previously stated, the full motor capacity is a function of ambient fluid temperature and flow past the motor.When the ambient temperature exceeds the temperature at which the motor performance is based, the motor mustbe derated and/or cooling velocity increased. Table 4-8 provides typical derating criteria for hermeticallysealed/canned type submersible motors, which use de-ionized water as the primary internal motor fluid. Suchmotors should not be used in applications which exceed 60°C (140°F) regardless of any special provisionsincorporated into the system. AWWA specifications state that the motor temperature shall not exceed the allowableoperating temperature of the motor thrust and radial bearings, and in no case shall it exceed the temperature ratingof the motor insulation system.

When the service duty exceeds 40°C (104°F) pumps and motors fitted with NBR rubber components are subject toreduced life if not replaced on a regular basis. A minimum replacement interval of three years is recommended.


Section 4

Section 4B Submersible Motor Cooling

High temperature elastomers (rubber compounds) are recommended any time the normal ambient fluid temperatureexceeds 104°F. In application which exceed 60°C (140°F), the use of submersible motors which use dielectric oil forinternal cooling and lubrication should be used. Hot water applications for standard water well submersible motorsis discussed latter in this section.

4-21

Table 4-8: Allowable % of Max. Nameplate Amps Derated for Ambient Water Temp. @ .5 fps

Water Temp. 0 - 3 Hp 5 - 15 Hp 20 - 250 Hp

30°C (86°F) 100% 100% 100%35°C (95°F) 100% 100% 90%

40°C ( 104°F) 100% 90% 80%45°C (113°F) 90% 80% 70%50°C (122°F) 80% 70% 60%55°C (130°F) 70% 60% 45%60°C (140°F) 50% – –

Note: Derating % is based on a ambient fluid temperature of 30°C (86°F) @ 0.5 fps, consult motor manufacturefor specific maximum full-load cooling water temperature without derating. Typical base ambient fluidtemperature rating for various manufactures of submersible motors used in the water supply industry range from25°C to 40°C, with 30°C being the most prominent.

Motor Over-Temperature Protection. Many motor manufactures can provide motor modification which allowwinding temperatures to be monitored directly from the surface through auxiliary controls such as the GrundfosCU3 or MTP75. Built in monitoring devices can be damaged during insulation resistance (megger) checks. Smallmotors are often equipped with built in temperature protection in the form of a thermal switch. In the absence of adirect winding temperature monitoring device or built in protection, over-temperature protection is providedindirectly via overload protection.

Motor Submergence. Allowable motor temperature is based upon having at least atmospheric pressure on thewater surrounding the motor. Where fluid temperatures exceed 30°F (104°), addition submergence is recommended,as increase pressure will protect the internal motor fluid from boiling, when the pump stops. The higher thesubmergence pressure, the higher the boiling point temperature and the greater the temperature safety margin.Table 4-9 lists the recommended water submergence over the motor in hot/warm water applications. Typicallypump NPSH requirements corrected for temperature will be greater than the values listed in the table. The greaterof the two values should be used in the design process.

Table 4-9: Motor Submergence in Warm/Hot Water Applications

Water Temp. Submergence Depth/Pressure

Feet of water (ft.) psi Meters of water (m)

30°C (86°F) 1.5 0.7 0.535°C (95°F) 3.0 1.3 1.040°C (104°F) 4.5 1.9 1.545°C (113°F) 9.0 3.9 3.050°C (122°F) 18.0 7.8 6.055°C (130°F) 27.0 11.7 9.060°C (140°F) 36.0 15.6 12.0

Note: Motor rating based on 30°C ambient water temperature at 0.5 fps or greater cooling flow velocity.

Applications where submergence pressure/suction conditions are changed as a result of the use of packers and wellseals above the pump, or vacuum systems should be carefully scrutinized. Reduced intake/suction pressures cancreate both motor and pump problems; pumps can be damaged as a result of insufficient NPSH, motors aresusceptible to temperature related failures associated with inadequate submergence pressure. Derating of the motorto the next larger motor size should be considered when prolong application under reduced intake pressure islikely.


Sect

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4

Motor Jacket/Shroud/Flow Inducer SleeveOn some installations it is necessary to use a motor jacket or shroud to insure that all, or some portion of theproduced fluid pass by the motor in order to carry away the heat generated. In some cases, the motor jacket is usedto increase velocity (create turbulent flow) in order to prevent the formation of deposit and inhibit corrosion. Amotor jacket should be used/ considered under the following operating scenarios:

1. Top-feeding (cascading) wells can feed the water directly into the pump without its flowing past the motor if thewell is not cased to below the motor, or casing is perforated above the motor.

2. Flow may be inadequate when the motor is in a large body of water or a casing much larger than the motor, orif delivery is very low, or in sump/wet pit tank applications.

3. If the groundwater is aggressive or contains chloride, the corrosion rate will double for every 15°C increase intemperature between the motor metallic housing and water. The motor housing is generally 5-15°C warmer thanthe produced water. A cooling sleeve will therefore reduce the risk of motor corrosion by keeping the exteriormotor surface temperature lower during operation.

4. If the well water contains a significant amount of iron (iron bacteria), manganese and calcium. These substanceswill be oxidized and deposited on the motor surface. In case of low flow past the motor, incrustation build-upforms a heat insulating layer of oxidized minerals, which may result in hot spots in the motor winding insulation.This temperature increase may reach values, that impare the insulating system, and consequently the motor life.A cooling sleeve will insure turbulent flow past the motor prohibiting incrustation build-up and optimize cooling.

A cooling shroud/motor jacket should be selected so as to keep the maximum fluid velocity past the motor to 15fps (12 fps by AWWA specs.). At the higher velocities, erosion can be significantly accelerated in the presence ofabrasives and increase intake losses can impare pump performance. Head loss for various motor O.D. andcasing/shroud I.D. combinations are listed in Table 4-10, and should be considered under marginal submergenceand suction conditions. A fluid velocity of 3 fps is generally considered optimum and 0.5 fps is the minimumcooling velocity value. The actual fluid velocity past the motor can be calculated using the formula:

where; Casing or shroud ID and motor OD values are in inches, and velocity (past the motor) is in fps


Velocity (past motor) = gpm/2.45 (ID casing)2 – (OD motor)2

Table 4-10: Annular Space Head Loss (Hf) from Flow Past Motor (ft. of Water)

Motor (Nominal) 4” 4” 4” 6” 6” 6’ 8” 8”Casing I.D. 4.25” 5” 6” 6” 7” 8” 8.1” 10”

25 0.350 1.2100 4.7 0.3 1.7150 10.2 0.6 0.2 3.7200 1.1 0.4 6.3 0.5 6.8250 1.8 0.7 9.6 0.8 10.4300 2.5 1.0 13.6 1.2 0.2 14.6400 23.7 2.0 0.4 24.6500 3.1 0.7 37.3 0.6600 4.4 1.0 52.2 0.8800 1.51000 2.4

Note: The tabulated friction loss values assume maximum motor length for the specified nominal motor size anda smooth casing/sleeve ID, and include entry and exit losses.

gpm

Typical Motor Jacket/Shroud Configurations. The motor shroud is generally of the next nominal diameter ofstandard pipe larger than the motor or the pump, depending on the shroud configuration used. The tubular/pipematerial can be plastic or thin walled steel (corrosion resistant materials preferred). The cap/top must accommodatepower cable without damage and provide a snug fit, so that only a very small amount of fluid can be pulledthrough the top of the shroud. The fit should not be completely water tight as ventilation is often required to allowescape of the air or gas that might accumulate. The shroud body should be stabilized to prevent rotation and


Section 4

Section 4B Submersible Motor Cooling

maintain the motor centered within the shroud. The shroud length should extend to a length of 1-2 times theshroud diameter beyond the bottom of the motor when possible. Shrouds are typically attached immediately abovethe pump intake or at the pump/column correction.

A typical motor sleeve/shroud selection example is sited below and illustrated in Figure 4-4:

Example 4-1:

A six-inch motor and pump that delivers 60 gpm will be installed in a 10” well, 90 gpm past the motor isrequired assuming 10” ID well (from Table 4-7). An 8” or smaller sleeve must be added to the pump to providea cooling flow velocity of 0.5 fps or greater.

If a well feeds water from above the pump, has a casing/chamber too small to allow a motor jacket/sleeve onthe pump, and does not have adequate level and flow to allow raising the pump above the inflow, it isdifficult to properly cool the motor. When possible, the casing depth should be increased to allow flow tocome from below the motor. If this is not practical, adequate flow past the motor can usually be attained byemploying a motor jacket with a stringer pipe or by using a jet tube as shown in Figure 4-5.

4-23

Figure 4-4: Typical Motor Jacket Installation Scenarios

Pump

Top of SleeveClosed andClamped orBolted to PumpAbove Intake

Flow InducerSleeve

Spacers at 3 or4 Points Aroundthe Inside ofthe Sleeve areRecommended to HoldMotor Centered and AvoidLoosening Top During Installation

Pump Intake

Motor

All Water FlowsPast Motor

Casing

Fluid Entry

Pump

Jacket

Motor

Figure 4-5: Unusual Motor Jacket/Cooling Installation Scenarios

1/4" ID Tube TappedInto Pump Outlet

Straps with SpacersAlongside Tubing toPrevent Crushing byStraps or Installation

Jet of Water fromTube Creates SomeFlow Past Motor

Pump

Motor

Approx.1 Foot

FLCasing

Pump

Jacket

Motor

Fluid Entry

Typical Flow Inducer Sleeve Cutaway View

Flow Inducer Jet Tube to Promote Flow Past Motor Only When Other Methods Are Impractical

The table shows the recommended number of starts ofintermittent operation:

Special (Non Water Well) ApplicationsA cooling shroud should be used in all static horizontal andvertical installations where water can directly enter the pumpintake, without crossing the motor surface. In addition tofocusing the pumped fluid to dissipate motor heat, a motorshroud can be used to improve suction conditions byreducing vortices. Such applications include fountains andpump-out tanks, where the ambient fluid temperature is oftenhigher than groundwater temperatures. In such installations;motor submergence-temperature considerations, as well aspump intake requirement must be carefully considered.

A typical horizontal pump out tank application is illustrated in Figure 4-6. Vertical application should be handled asillustrated in Figure 4-7, which is analogues to top feeding water well application.


Sect

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4


Table 4-11: Intermittent Operation

Motor type Recommended number of starts

*MS 402 4” Min. 1 pr. year*MS 4000 4” Max. 30 pr. hour*MS 6000 6” Max. 300 pr. day

Franklin 6” Min. 1 pr. yearFranklin 8” Max. 100 pr. day

Mercury 6” Min. 1 pr. yearMax. 20 pr. hour

Mercury 8” Min. 1 pr. yearMax. 10 pr. hour

Figure 4-6: Cooling Sleeve on Horizontally Installed Motor in a Tank

Figure 4-7: Cooling Sleeve – Vertically InsulatedMotor in a Tank

W/O Cooling Shroud

W Cooling Shroud

*MS - Grundfos Motor

Hot Water Applications (Hermetically Sealed/Canned Type-Submersible Motors). When the pump-motor operatesin water hotter than 86°F (30°C), 104°F (40°C) for some manufactures, the best motor cooling and most economicalmotor size result when the cooling flow rate velocity past the motor is minimum of 3 feet per second (fps).


Section 4

Section 4B Submersible Motor Cooling 4-25

When selecting the correct motor to drive a pump at elevated water temperatures, and 3 fps cooling flowvelocity can be maintained, a heat factor multiplier can be applied to the load in order to properly select amotor. The heat factor sizing multiplier motor selection process is outlined and illustrated by example as follows:

Step 1: Determine pump flow (gpm) delivery require for various well/sleeve diameters and motorcombinations using Table 4-12. The flow velocity past the motor must be a minimum 3 fps. Add a motorjacket/sleeve to obtain a cooling velocity of 3 fps.

Step 2: Determine pump horsepower (Hp) required .

Step 3: Multiply the pump Hp requirement by the heat factor multiplier from Table 4-13.

Step 4: Select a rated Hp motor from Table 4-14, whose Service Factor Horsepower (SFHp) is at least the valuecalculated in step 3.

Example 4-2: A 6” pump end requiring 39 Hp input will pump 124°F water in an 8” well at a delivery rate of140 gpm. From Table 4-12, a 6” flow sleeve will be required to increase the flow rate to at least 3 fps.

Using Table 4-13, the 1.62 heat factor multiplier is selected because the Hp required is over 30 Hp and watertemperature above 122°F. Multiply 39 x 1.62 which equals 63.2. This is the minimum service factorhorsepower motor which is usable at 39 Hp in 124°F water. Using Table 4-14, select a motor with a servicefactor horsepower above 63.2. A 60 Hp motor has a SFHp of 69, so a 60 Hp motor may safely be used.

Table 4-12: Minimum Flow (gpm) Requirement to Obtain 3 fps Flow Velocity

Inches Castingor Sleeve I.D. 4” Motor 6” Motor 8” Motor

4 15 – –5 80 – –6 160 52 –7 – 150 –8 – 260 6010 – 520 33012 – – 65014 – – 102016 – – 1460

Table 4-13: Heat Factor Multiplier @ 3 fps Flow Velocity

Maximum 1/3 - 5 7 1/2 - 30 Over 30Water Temp Hp Hp Hp140°F (60°C) 1.25 1.62 2.00131°F (55°C) 1.11 1.32 1.62122°F (50°C) 1.00 1.14 1.32113°F (40°C) 1.00 1.00 1.14104°F (45°C) 1.00 1.00 1.0095°F (35°C) 1.00 1.00 1.00

Table 4-14: Service Factor Horsepower (SFHp) @ S.F. = 1.15)

Hp SFHp Hp SFHp Hp SFHp Hp SFHp1/3 .58 3 3.45 25 27.50 100 115.001/2 .80 5 5.75 30 34.50 125 143.753/4 1.12 7 1/2 8.65 40 46.00 150 172.501 1.40 10 11.50 50 57.50 175 201.25

1 1/2 1.95 15 17.25 60 69.00 200 230.002 2.50 20 23.00 75 86.25 250 287.50


Sect

ion

4

Section 4C Motor Insulation Resistance4-26

The formula, Rm = kV + 1 can be used to calculate the minimum insulation resistance (Rm in megohms) for anymotor, based on rated/ nameplate voltage (kV in kilovolts). Using the formula, a 2300V motor should have aminimum Rm value of 3.3 megohms. The recommended megohmmeter DC test voltages based on motor nameplatevoltage are specified in Table 4-16 below:

Cable Splice. Insulation resistance for cablesplices should be no less than 10 megohmsunder submerged conditions. See Section 4Dfor additional information regarding cable andcable splice insulation resistance levels.

Insulation History. The only accurate way topredict insulation failure is to maintain ahistory of the insulation resistance readings.

Over a period of months or years these readings will tend to indicate a trend. Sudden or gradual drop insulationresistance after a pump is installed usually predicts failure, indicating a progressive weakening of insulation at somepoint in the cable or motor such as a damaged lead, leaky connector or splice, or surge damaged motor winding.

4C MOTOR INSULATION RESISTANCE

Insulation ResistanceInsulation resistance in a submersible pumping system is a measure of the motors and/or cables ability to withstandnormal voltage and surge voltages, without breakdown and failure. An “adequate” level of insulation resistance isnot a constant value, but depends on the installation voltage and conditions, and whether the measured resistanceis lowered by a specific weak point or by widely distributed conductance such as in cable insulation material itself.For this reason, values for acceptable resistance cannot be specific.

Insulation Resistance Measurements. Insulation resistance measurements should be taken at the time of initial motorinstallation and periodically thereafter. In deep set submersible installations, measurements should be takenthroughout the installation process, to detect potential cable insulation/connection damage before the unit iscompletely installed. Table 4-15 describes the condition of the insulation system for a submersible motor system of600V or less based on megohmmeter (megger) readings.

Table 4-15: Insulation Resistance (Megger Readings) & Motor Condition

Condition of Motor and Leads OHM Value MEGOHM Value

A newmotor (without drop cable). 20,000,000 (or more) 20.0 (or more)

A used motor which can be reinstalled in the well 10,000,000 (or more) 10.0 (or more)

MOTOR IN WELL. Ohm readings are for drop cable plus motor.

A new motor in the well. 2,000,000 (or more) 2.0 (or more)

A motor in the well in reasonable good condition. 500,000 - 20,000,000 0.5 - 2.0

A motor which may have been damaged by lightning or with 20,000 - 500,000 0.02 - 0.5damaged leads. Do not pull the pump for this reason.

A motor which definitely has been damaged or with damaged cable. 10,000 - 20,000 0.01 - 0.02The pump should be pulled and repairs made to the cable or the motor replaced. The motor will not fail for this reason alone, but it will probably not operate for long.

A motor which has failed or with completely destroyed cable less than 10,000 0 - 0.01insulation. The pump must be pulled and the cable repaired or the motor replaced.

Note: Table is applicable to motor nameplate voltage ratings of 600V or less.

Table 4-16: Insulation Resistance DC Test Voltages

Rated Motor AC Voltage Recommended DC Test Voltage

600V and less 500 VDC

601V to 1000V 500 to1000 VDC

1001V and up *500 to 2500 VDC

* 2500 VDC optimum


Section 4

Section 4C Motor Insulation Resistance 4-27

Dielectric Absorption RatioWhen a single point megohometer test indicates a potential problem within the insulation system, a dielectricabsorption ratio (DAR) test should be conducted. The DAR test will further quantify the suitability of the motorand/or cable system for operation. The DAR is obtained by taking megohmmeter readings at thirty seconds andsixty second intervals. Readings at one and ten minutes is recommended, but is often impractical under fieldconditions.

The DAR is obtained by dividing the second (60 sec. or 10 min.) reading by the first (30 sec. or 1 min.) reading andis based on a good insulation system increasing its resistance when subjected to a test voltage for a period of time.The condition of the insulation system based on DAR test results are described in Table 4-17 below.

If a low insulation resistance reading isobtained in both the individual meggerand dielectric absorption ratio test, themotor should be replaced and orrepaired as applicable. The same testvoltage specified for individual meggerreadings should be used whenconducting the DAR test.

Table 4-17: Dielectric Absorption Ratio & Motor Condition

10 minute: 1 minute 60 second: 30 second

Dangerous = less than 1.0 Poor = less than 1.1

Poor = 1.0 to 1.4 Questionable = 1.1 to 1.24

Questionable = 1.5 to 1.9 Fair = 1.25 to 1.3

Fair = 2.0 to 2.9 Good = 1.4 to 1.6

Good = 3.0 to 4.0 Excellent = over 1.6

Excellent = over 4.0


Sect

ion

4

Section 4D Submersible Power Cable4-28

4D SUBMERSIBLE POWER CABLESubmersible Power CablePower is transmitted from the starter/controller to the submersible motor through a marine duty power cable,typically consisting of three flexible stranded conductors of the proper size to carry the motor full load amperes(FLA) at its rated voltage. AWWA standards require a separate ground wire to be provided (ie. 3-wire cable systemsare equipped with three power conductors and a ground wire of the same size).

Proper cable selection is a function of motor load, voltage, available space, length (setting depth) and environment.Typical conductor insulation materials are synthetic rubber (RW, RUW, TW, etc.), plastic (PVC, XPLE, etc.) or specialpolymer (FPE, hypalin, EPR - EPDM, etc.). Special cable insulations are often recommended or required for severduty or special applications such as; gas, hydro - carbon, heat, variable frequency, etc.

Cable can be provided as three or more separate individual or, twisted conductors, molded side by side in a flatcable configuration or three conductors with a round common jacket. Refer to Table 4-18 for general submersiblepower cable physical data (weight and diameter). Armored cable is also available for special applications, but istypically not employed in the water supply industry. Cable is supported and attached to column/drop pipe bymeans of cable clamps, tape or bands. One extra foot of cable for each fifty feet of length should be allowed plusan additional ten to fifty feet for surface connections.

Table 4-18: Typical Submersible Power Cable Physical Data

Type I3 Conductors and ground

in a Common Jacket(4 wire total)

Type II3 Conductors and ground

in Separate Jackets(4 wire total)

Type III3 Conductors in aCommon Jacket(3 wire total)

Type IV3 Conductors in Separate Jackets(3 wire total)

600 Volt (115, 208, 230, 460 and 575 Volt Motors) 5000 Volt (2300 Volt Motors)

Notes: 1. Types I and II cables are typically insulated and jacketed with synthetic rubber, PVC or XLPE. 2 Types II and IV are often supplied paralleled in a flat cable configuration, or in a twisted configuration for smaller sizes.

Type I and II cable include 3 power conductors and a ground conductor.3. AWWA minimum stranding and insulation requirements; No. 10 and smaller - 7 strand/ Class B, No. 9 through No. 2 - 19

strand/ Class C, No. 1 through 4/0 - 19 strand / Class B. Minimum conductor area to meet minimum ICEA (InsulatedCable Engineers Association) code for operation in free air.

4. Verify actual cable weight per foot with manufacture for greater accuracy, as weight and diameter will very with insulationsystem and manufacture.

CableSize

AWG O.D. Weight O.D. (in.) Wt. (lbs./ft.) O.D. Weight O.D. (in.) Wt. (lbs./ft.)MCM (in.) (lbs./ft.) per cable for 4 cables (in.) (lbs./ft.) per cable for 3 cables

14 .39 .16 .19 .1012 .43 .20 .21 .1310 .64 .32 .27 .188 .76 .44 .31 .29 1.02 .69 .39 .436 91 .65 .36 .43 1.10 .85 .43 .524 1.02 .90 .42 .64 1.21 1.12 .47 .712 1.15 1.26 .48 .97 1.33 1.46 .53 .991 1.34 1.68 .58 1.26 – – – –0 1.43 2.0 .62 1.54 1.51 2.09 .62 1.4900 1.53 2.41 .67 1.91 1.61 2.56 .66 1.87000 1.64 2.89 .72 2.36 – – – –0000 1.80 3.58 .78 2.93 1.82 3.40 – –250 1.97 5.88 .90 4.82 – – – –300 2.09 6.60 .95 5.62 – – – –350 2.20 7.34 1.00 6.50 2.51 4.8 – –400 2.34 8.18 1.05 7.25 – – – –500 2.25 9.30 1.13 8.87 – – – –


Section 4

Section 4D Submersible Power Cable 4-29

Cable SelectionMaximum cable lengths are generally calculated to maintain 95% of service entrance voltage at the motor running atmaximum nameplate amps, and to maintain adequate starting torque. Calculations take into account basic cableresistance, reactance, power factor and temperature rise cable larger than specified may always be used, and willreduce power consumption. Table 4-19 tabulates copper cable sizes for various cable lengths vs motor size. Figure4-9 can be used to graphically select power cable when motor amperes are known.

Electrical losses in the cable are charged to the overall plant efficiency (OPE). Table 4-21 and Figure 4-10 can beused to estimate power cable losses for the purposes of estimating operating cost and OPE. The use of powercables smaller than the minimum sizes as permitted by code or recommended by the motor manufacture willgenerally void the motor warranty. Understized cable sizes will cause reduced starting torque and poor motoroperation.

Mixed Cable. In a submersible pump installation any combination of cables sizes may be used provided they do notexceed the individual maximum conductor ampacity limit and the aggregate voltage drop does not exceed 5% ofthe motor nameplate voltage while operating at full load. Mixed cable sizes are most often encountered when apump is being replaced with a larger horsepower unit. Table 4-20 can be used to determine maximum conductorampacity. Figure 4-12 can be used to determine conductor voltage drop to insure adequate voltage delivery to themotor.

Cable Splice. When the downhole power cable (drop cable) must be spliced or connected to the motor leads, it isnecessary that the splice be water tight. Under normal service conditions, the splice can be made usingcommercially available potting compounds, heat shrink or tape. Each type of splicing methods is affective whenmade by competent personnel, potted or head shrink splices are recommended when submergence pressuresexceeds 25 psi (60’). A cable splice should exhibit a minimum insulation resistance of 10 megohms, measured in asubmerged state after 24 hours in water. A typical low voltage (< 600V) tape splice is illustrated below in Figure 4-8.

When three conductors are encased in a single outershealth, tape individual conductors as described,staggering joints. Total thickness of tape should be noless than the thickness of the conductor insulation.

Motor Lead. Most manufactures will provide a factorymotor lead assembly, pre-potted and designed toprovide a water tight connection between it and themotor terminals. Typical motor lead length range from48” to 150” and are generally spliced to the drop cableimmediately above the pump. Minimum wire sizes(AWG) for factory provided motor lead assemblies, bynominal motor size are; 4” - #14 to #12, 6” - #10 to #8,8” - #4 and 10” - #2.

In general, a motor lead assembly should not be reused as rubber compounds typically used in there constructionwill set with time, making a water tight connection difficult. The manufactures installation instructions, whichincludes pot head connecting torque vales and lubrication requirements, should be strictly observed.

Figure 4-8: Tape Splice


Sect

ion

4


Tab

le 4

-19

: M

ax

imu

m S

ub

me

rsib

le P

ow

er

Ca

ble

Le

ng

th (

Ma

x.

Ca

ble

Le

ng

th i

n f

ee

t -

Sta

rte

r to

Mo

tor)

Mo

tor

Rat

ing

AW

G C

op

per

Win

e Si

zeM

CM

Co

pp

er W

ire

Size

Vo

lts

HP

14

12

10

86

43

21

000

000

0000

250

300

350

400

500

1/2

3/4 1

1 1/

22 3 5

7 1/

210 15 20 25 30

710

510

430

310

240

180

110* 0 0 0 0 0 0

1140

810

690

500

390

290

170 0 0 0 0 0 0

1800

1280

1080

790

610

470

280

200 0 0 0 0 0

2840

2030

1710

1260

970

740

440

310

230*

160 0 0 0

4420

3160

2670

1960

1520

1160

690

490

370

250*

190* 0 0

4140

3050

2360

1810

1080

770

570

390

300*

240* 0

5140

3780

2940

2250

1350

960

720

490

380

300*

250*

3610

2760

1660

1180

880

600

460

370*

310*

4430

3390

2040

1450

1090

740

570

460

380*

5420

4130

2490

1770

1330

910

700

570

470

3050

2170

1640

1110

860

700

580

3670

2600

1970

1340

1050

840

700

4440

3150

2390

1630

1270

1030

850

5030

3560

2720

1850

1440

1170

970

3100

2100

1650

1330

1110

3480

2350

1850

1500

1250

3800

2570

2020

1640

1360

4420

2980

2360

1900

1590

1/2

3/4 1

1 1/

22 3 5

7 1/

210 15 20 25 30

930

670

560

420

320

240

140* 0 0 0 0 0 0

1490

1080

910

670

510

390

230

160* 0 0 0 0 0

2350

1700

1430

1060

810

620

370

260

190* 0 0 0 0

3700

2580

2260

1670

1280

990

590

420

310

210* 0 0 0

5760

4190

3520

2610

2010

1540

920

650

490

330

250* 0 0

8910

6490

5460

4050

3130

2400

1430

1020

760

520

400

320*

260*

8060

6780

5030

3890

2980

1790

1270

950

650

500

400

330*

9860

8290

6160

4770

3660

2190

1560

1170

800

610

500

410*

7530

5860

4480

2690

1920

1440

980

760

610

510

9170

7170

5470

3290

2340

1760

1200

930

750

620

8780

6690

4030

2870

2160

1470

1140

920

760

8020

4850

3440

2610

1780

1380

1120

930

9680

5870

4160

3160

2150

1680

1360

1130

6650

4710

3590

2440

1910

1540

1280

7560

5340

4100

2780

2180

1760

1470

8460

5970

4600

3110

2450

1980

1650

9220

6500

5020

3400

2680

2160

1800

7510

5840

3940

3120

2520

2110

200V

-208

V60

Hz

Thre

e Phas

eThre

e W

ire

230V

60H

zThre

e Phas

eThre

e W

ire

1/2

3/4 1

1 1/

22 3 5

7 1/

210 15 20 25 30 40 50 60 75 10

012

515

017

520

025

0

3770

2730

2300

1700

1300

1000

590

420

310 0 0 0 0 0 0 0 0 0 0 0 0 0 0

6020

4350

3670

2710

2070

1600

950

680

500

340* 0 0 0 0 0 0 0 0 0 0 0 0 0

9460

6850

5770

4270

3270

2520

1500

1070

790

540

410

330*

270* 0 0 0 0 0 0 0 0 0 0

9070

6730

5150

3970

2360

1690

1250

850

650

530

430

320* 0 0 0 0 0 0 0 0 0

8050

6200

3700

2640

1960

1340

1030

830

680

500*

410* 0 0 0 0 0 0 0 0

5750

4100

3050

2090

1610

1300

1070

790

640

540*

440* 0 0 0 0 0 0

5100

3800

2600

2000

1620

1330

980

800

670*

550* 0 0 0 0 0 0

6260

4680

3200

2470

1990

1640

1210

980

830

680*

500* 0 0 0 0 0

7680

5750

3930

3040

2450

2030

1490

1210

1020

840

620* 0 0 0 0 0

7050

4810

3730

3010

2490

1830

1480

1250

1030

760*

600* 0 0 0 0

5900

4580

3700

3060

2250

1810

1540

1260

940

740*

630* 0 0 0

7110

5530

4470

3700

2710

2190

1850

1520

1130

890*

760*

670*

590* 0

5430

4500

3290

2650

2240

1850

1380

1000

920*

810*

710* 0

5130

3730

3010

2540

2100

1560

1220

1050

930*

810* 0

5860

4250

3420

2890

2400

1790

1390

1190

1060

920* 0

3830

3240

2700

2010

1560

1340

1190

1030 0

4180

3540

2950

2190

1700

1460

1300

1130

760

4850

4100

3440

2550

1960

1690

1510

1310

865

460V

60H

zThre

e Phas

eThre

e W

ire


Section 4


Tab

le 4

-19

: M

ax

imu

m S

ub

me

rsib

le P

ow

er

Ca

ble

Le

ng

th (

Ma

x.

Ca

ble

Le

ng

th i

n f

ee

t -

Sta

rte

r to

Mo

tor)

(co

nti

nu

ed

)

Mo

tor

Rat

ing

AW

G C

op

per

Win

e Si

zeM

CM

Co

pp

er W

ire

Size

Vo

lts

HP

14

12

10

86

43

21

000

000

0000

250

300

350

400

500

1/3

1/2

130

100

210

160

340

250

540

390

840

620

1300

960

1610

1190

1960

1460

2390

1780

2910

2160

3540

2630

4210

3140

5060

3770

5680

4240

6390

4770

7110

5320

7680

5750

8790

6590

1/3

1/2

550

400

880

650

1390

1020

2190

1610

3400

2510

5250

3880

6520

4810

7960

5880

9690

7170

1177

087

2014

320

1062

017

050

1266

020

460

1521

022

980

1710

025

850

1926

028

750

2144

031

070

2320

035

580

2660

03/

41.

0030

025

048

040

076

063

012

0099

018

7015

4028

9023

8035

8029

6043

7036

1053

3044

1064

7053

6078

7065

2093

8077

8011

250

9350

1264

010

510

1422

011

840

1581

013

180

1709

014

260

1957

016

350

1.50

2.00

190

150

310

250

480

390

770

620

1200

970

1870

1530

2320

1910

2850

2360

3500

2930

4280

3620

5240

4480

6300

5470

7620

6700

8630

770

9810

8890

1098

010

080

1196

011

130

1386

013

170

3.00

5.00

120 0

190

110*

300

180

470

280

750

450

1190

710

1490

890

1850

1110

2320

1390

2890

1740

3610

2170

4470

2680

5550

3330

6450

3870

7580

4550

8690

5210

9740

5840

1177

070

607.

5010

.00

0 00 0

120* 0

200

160*

310

250

490

390

610

490

750

600

930

750

1140

930

1410

1160

1720

1430

2100

1760

2400

2030

2760

2370

3120

2700

3430

3000

4040

3590

15.0

00

00

017

0*27

034

043

053

066

082

010

2012

6014

6017

0019

4021

7026

10

115V

60H

zSi

ngl

e Phas

e

230V

60 H

zSi

ngl

e Phas

e

1/2

3/4 1

1 1/

22 3 5

7 1/

210 15 20 25 30 40 50 60 75 10

012

515

017

520

0

5900

4270

3630

2620

2030

1580

920

660

490

330* 0 0 0 0 0 0 0 0 0 0 0 0

9410

6810

5800

4180

3250

2530

1480

1060

780

530

410* 0 0 0 0 0 0 0 0 0 0 0

9120

6580

5110

3980

2330

1680

1240

850

650

520

430* 0 0 0 0 0 0 0 0 0

8060

6270

3680

2650

1950

1340

1030

830

680

500*

410* 0 0 0 0 0 0 0

5750

4150

3060

2090

1610

1300

1070

790

640*

540* 0 0 0 0 0 0

4770

3260

2520

2030

1670

1240

1000

850

690* 0 0 0 0 0

5940

4060

3140

2530

2080

1540

1250

1060

860

640* 0 0 0 0

3860

3110

2560

1900

1540

1300

1060

790*

630* 0 0 0

4760

3840

3160

2330

1890

1600

1310

970

770*

660* 0 0

5830

4710

3880

2860

2310

1960

1600

1190

950

800

700* 0

4770

3510

2840

2400

1970

1460

1160

990*

870*

760*

5780

4230

3420

2890

2380

1770

1400

1190

1050

*92

0*

7030

5140

4140

3500

2890

2150

1690

1440

1270

1110

*

8000

5830

4700

3970

3290

2440

1920

1630

1450

1260

5340

4520

3750

2790

2180

1860

1650

1440

5990

5070

4220

3140

2440

2080

1860

1620

6530

5530

4610

3430

2650

2270

2030

1760

7580

6410

5370

3990

3070

2640

2360

2050

575V

60H

zThre

e Phas

eThre

e W

ire

1.*

Lengt

hs

with

out as

terisk

mee

t U

.S. N

EC a

mpac

ity f

or

eith

er indiv

idual

or

jack

eted

conduct

ors

at 75

°C (

167°

F) a

nd 3

0°C (

86°F

) am

bie

nt.

2.*

Lengt

hs

mar

ked w

ith a

ster

isk

* m

eet U

.S. N

EC a

mpac

ity o

nly

for

indiv

idual

conduct

ors

at 75

°C in f

ree

air

or

wat

er, not in

conduit.

3.

The

NEC a

mpac

ity r

equirem

ent fo

r m

oto

r bra

nch

circu

its is

bas

ed o

n a

25%

contin

uous

moto

r ove

rload

.4.

Flat

mold

ed c

able

is

consi

der

ed to b

e ja

cket

ed.

5.Tab

le b

ased

on a

mai

nta

inin

g m

oto

r te

rmin

al v

olta

ge a

t 95

% o

f se

rvic

e en

tran

ce v

olta

ge, ru

nnin

g at

max

imum

nam

epla

te a

mper

es. If a

max

imum

allo

wab

le v

olta

ge d

rop 3

% (

ie97

% o

f se

rvic

e en

tran

ce v

olta

ge, m

ulti

ply

tab

ula

ted v

alues

be

.6 f

or

max

imum

cab

le lim

its. In

gen

eral

volta

ge d

rop s

hould

be

mai

nta

ined

at 3V

/100

ft.

or

less

.6.

Tab

le b

ased

on c

opper

wire.

If

alum

inum

wire

is u

sed, it

should

be

at lea

st tw

o s

izes

lar

ger

(ie.

# 1

2 Copper

= #

10

Alu

min

um

) or

multi

ply

tab

ula

ted c

able

len

gth v

alues

by

.57.

Cab

le len

gth c

orr

ectio

ns

fact

or

for

ambie

nt te

mper

ature

are

lis

ted a

s fo

llow

s:8.

1 fo

ot = .30

5 m

eter

9.The

cable

len

gth b

etw

een the

serv

ice

entran

ce (

met

erin

g) to a

thre

e phas

e m

oto

r st

arte

r/co

ntrolle

r sh

ould

not ex

ceed

25%

of

the

tabula

ted len

gths

above

, to

ass

ure

rel

iable

sta

rtin

g.

Am

bie

nt Te

mp

10°C

/ 50

°F20

°C/

68°F

30°C

/ 86

°F40

°C/

104°

F50

°C/

122°

FCab

le L

engt

hCorr

ectio

n F

acto

r1.

181.

101.

00.8

2.5

8


Sect

ion

4


Figure 4-9: Graphical Submersible Cable Selection Chart - 3 phase/60 Hz (Motor Amperes vs Cable Length)

Note: 1. To use selection chart, find intersection of motor amperes and cable length - use any cable to Right of this point.Example: 150 HP, 440 volt motor operating at full load will draw 203.2 amperes; checking selection chart we findthat 0000 is the minimum recommended cable size for any setting up to 800 feet. For deeper settings, larger cablemust be used. A 900 foot setting on the above motor would require a minimum cable size of 300 MCM.

2. Table based on 5% voltage drop - 75°C copper conductor temp. and 30°C ambient temp. Maximum ampere valuefor each cable size must be reduced if ambient temperature exceeds 30°C (see note 7 in Table 4-19).

Table 4-20: Maximum Copper Conductor Ampacity & Motor Amps

Wire Max. Conductor Max Motor Wire Max. Conductor Max. MotorSize Ampacity Amps Size Ampacity Amps

(AWG) (NEC 310 – 16) (NEC 430 – 22) (MCM) (NEC 310 –16) (NEC 430–22)

14 15 12 250 255 20412 20 16 300 285 22810 30 24 350 310 2488 50 40 490 335 2686 65 52 500 380 2044 85 68 600 420 3362 115 92 700 400 368

1/0 150 120 750 475 3802/0 175 140 1000 545 4363/0 200 160 – – –4/0 230 184 – – –

Notes: 1. Maximum ampacity for wires was taken from the National Electrical Code Table 310-16, Column 2 for wire typeRHW having a temperature rating of 75°C wet and 90°C dry. Not more than three conductors in raceway, conduitor direct burial (based on ambient temperature to 30°C).

2. Maximum motor amps is the ampacity divided by 1.25 as specified in N.E.C. article 430-22 for motor branch circuits.


Section 4


Figure 4-10: Graphical Submersible Cable Power Loss Chart (Motor Amperes vs Hp loss per 100 ft.)

Note: The above chart indicates the power loss (in horsepower) for each 100 feet of submersible cable. This loss must beconsidered in overall plant efficiency (OPE), calculations. Long range cost evaluation may dictate the use of a larger thannormal size cable.

Table 4-21: Submersible Power Cable Loss (Hp/100 ft. of Cable @ full load)

Motor Rating AWG Copper Wire Size MCM Copper Wire Size

Volts Hp 8 6 4 2 1/0 4/0 300 500

5 .082 – .026 .0167 1/2 .139 – .056 .05610 .291 – .117 .037 .04615 .460 – .184 .115 .07220 .564 .353 .221 .11330 .774 .484 .315 .154 .110 .06540 .778 .489 .248 .117 .10550 .762 .388 .277 .16460 .619 .440 .26175 .901 .641 .3805 .018 –

7 1/2 .035 –10 .074 –15 .139 – .05120 .225 – .08825 .350 – .12130 .482 – .195 .12140 .310 .195 .12250 .532 .332 .20960 .484 .304 .15575 .705 .442 .225 .160100 .855 .451 .322125 .589 .420 .256150 .856 .610 .359200 1.079 .637250 .990

Note: Cable Loss in BHp = (Loss from Table) x Actual Cable Length100

230V60 Hz

Three Phase

460V60 Hz

Three Phase


Sect

ion

4


Figure 4-12: Voltage Drop per 100 ft. of Cable

Figure 4-11: Drop Cable Resistance vs. Length

Table 4-22: Copper Wire Resistance (DCResistance in Ohm/100 ft. @ .75°C Cond. Temp.)

Wire Size

AWG MCM Ohms

14 – .32409312 – .20382010 – .1281788 – .0806286 – .0507124 – .031862– 2 .02006

1/0 – .0126482/0 – .0100013/0 – .0079314/0 – .006290

250 .005324300 .004436350 .003803400 .003327500 .001774600 .002218700 .001901750 .0017741000 .001330

Note: Graphed values are based on copper conductors.Aluminum conductor resistance can be calculated by:multiply the ohm values from the chart by 1.64.

SHADED AREA OF EACH CABLE SIZE SHOWS AMBIENT

TEMPERATURE RANGE FROM 30°C / 86°F TO 60°C / 140°F

CU = COPPER / AL - ALUMINUM

6

5

4

3

2

1

0

VO

LTA

GE

DR

OP

OV

ER

100

FE

ET

OF

CA

BL

E


Section 5

Section 5A Large Submersible Products



SECTION 5: GRUNDFOS SUBMERSIBLE PRODUCTS

5A LARGE SUBMERSIBLE PRODUCTS

• Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2• Features and Benefits of Grundfos Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2• Pump Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2• Single Stage Pump Performance Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2• Grundfos Submersible Pump Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

5B EXPLODED VIEW DRAWINGS AND MATERIALS

• Exploded Pump Drawing, Figures 5-1 to 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4• Materials Used in Construction, Table 5-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

5-1


Sect

ion

5

Section 5A Large Submersible Products5-2

5A LARGE SUBMERSIBLE PRODUCTSProduct OverviewThis section covers Grundfos’ line of large submersible pumps available for sale. Included in the following sectionsare tables listing specific pump data and single stage performance values at best efficiency point.

Exploded drawings (Figures 5-1 to 5-3 and Table 5-4) for 6”, 8” and 10” pumps show the major components andmaterials used in construction. Dimensions and weights for each model can be found in the Grundfos GroundwaterCatalog.

Features and BenefitsGrundfos 6”, 8” and 10” diameterpumps range in flow from 50 to1400 GPM and head pressures upto 2100 ft. Check valves are “builtin” all discharge chambers andupthrust washers are designed inall models to prevent excessivewear during periods of highdemand or start-up.

Pump ModelsTable 5-1 shows the pump modeldesignation and the flow rate foreach pump model.

Table 5-1: Grundfos Pump Models (Jan. 1999)

Pump Model GPM Pump Model m3/hr

85S 85 SP17 17150S 150 SP30 30230S 230 SP46 46300S 300 SP60 60385S 385 SP77 77475S 475 SP95 95625S 625 SP125 125800S 800 SP160 1601100S 1100 SP215 215

Note: One m3/hr equals 4.4 gpm. The values above have been roundedoff to 5 gpm per m3/hr.

Table 5-2: Single Stage Performance Data at Best Efficiency Point (Jan. 1999)

Pump Size H *H (Trim) NPSH **H, loss Power *Power Efficiency Thrust(gpm) (ft) (ft) (ft) (ft) (hp) (hp) (%) (lbf)

85S 43 – 17 5 1.1 – 73 45150S 41 – 14.5 5 1.9 – 75 106230S 44 37A,27B,24C 12 7 3.3 – 77 103300S 41 28A,24B 12 7 2.9 – 78 99385S 62 40A,35B 16 3 5.6 – 78 225475S 63 50A,36B 20 3 9.2 – 78 157625S 114 77A 28 17 19 14 80 337800S 104 76A 32 5 24 17.5 82 3931100S 120 90A 37 10 40 31 84 450

~ Data measurements taken at ambient temp., 60 Hz, 3450 rpm~ Conformance with ISO 2548, Annex B* Trimmed impeller (A, B, C) types**H, loss in pump inlet and check valve

Single Stage Performance DataTable 5-2 shows Grundfos Pumps single stage data at BEP. This data is used to estimate pump and motor size basedon required flow and head. See Section 6B.

Grundfos Submersible Pump DataTable 5-3 shows pump data, hp range, and efficiency data for Grundfos submersible pumps. Also shown areavailable materials and discharge sizes for all large Grundfos submersible pumps.


Section 5

Section 5A Large Submersible Products 5-3

Table 5-3: Grundfos Submersible Pump Data (Jan. 1999)

Pump Size Pump Nom. Flow Range Max. Head HP Discharge Available Efficiency(gpm) Dia. (inch) (gpm) (ft.) Range (npt) **Material (%)

85S 6 50-110 2000 1.5-50 3 A,B,C 73150S 6 75-200 2100 2-75 3 A,B,C 75230S 6 160-320 1400 5-75 3 A,B,C 77300S 6 200-400 1200 7.5-75 3,4 A,B,C 78385S 8 260-550 1200 10-100 *5 A,B 78475S 8 280-680 1300 10-125 *5 A,B 78625S 10 440-850 900 15-150 6 A,B 80800S 10 580-1080 700 20-125 6 A,B 821100S 10 600-1400 1100 30-250 6 A,B 84

* Adapters available to adapt 5” npt to 4” npt or 6” npt.** Material: A = 304SS, B = 316SS, C = 904L stainless steel.

Note: Minimum well casing diameter is the same as nominal pump diameter.


Sect

ion

5

Section 5B Exploded View Drawings & Materials5-4

Figure 5-1: Exploded View, 150S (Jan. 1999)

5B EXPLODED VIEW DRAWINGS & MATERIALS


Section 5

Section 5B Exploded View Drawings & Materials 5-5

Figure 5-2: Exploded View, 385S and 475S (Jan. 1999)


Sect

ion

5


Figure 5-3: Exploded View, 625S and 800S (Jan. 1999)


Section 5

Section 5B Exploded View Drawings & Materials 5-7

Table 5-4: Grundfos Submersible Pump Parts & Material List (Jan. 1999)

1 Valve casing Stainless 1,4301 304 1,4401 316steel

1d O-ring NBR

2 Valve cup Stainless 1,4301 304 1,4401 316steel

3 Valve seat Stainless 1,4301 304 1,4401 316steel

3a Lower valve Stainless 1,4301 304 1,4401 316seat retainer steel

3b Upper valve Stainless 1,4301 304 1,4401 316seat retainer steel

4 Top Stainless 1,4301 304 1,4401 316intermediate steel

chamber

5 Stop disc Carbon/GraphiteHY22 in

Teflon mass

6 Top bearing Stainless 1,4301 304 1,4401 316steel/NBR

6b Lower Stainless 1,4301 304 1,4401 316bearing steel/NBR

7 Neck ring NBR/PPS

8 Intermediate NBRbearing

8a Spacing Carbon/washer for Graphitestop ring HY22 in

Teflon mass

8b Stop ring Stainless 1,4301 304 1,4401 316steel

9 Intermediate Stainless 1,4301 304 1,4401 316chamber steel

10 Bottom Stainless 1,4301 304 1,4401 316intermediate steelchamber with

stop ring

11 Split cone Stainless 1,4301 304 1,4401 316nut steel

11c Nut for Stainless 1,4401 316L 1,4401 316Lstop ring steel

12 Split cone Stainless 1,4301 304 1,4401 316steel

13 Impeller Stainless 1,4301 304 1,4401 316steel

14 Suction inter- Stainless 1,4301 304 1,4401 316connector steel

Intermediate Stainless 1,4401 316 1,4401 316piece for steel6” motor

over 30 kW

15 Strainer Stainless 1,4301 304 1,4401 316steel

16 Shaft Stainless 1,4057 431 1,4460 329steel

17 Strap Stainless 1,4301 304 1,4401 316steel

18 Cable guard Stainless 1,4301 304 1,4401 316steel

18a Screw for Stainless 1,4301 304 1,4401 316cable guard steel

19 Nut for strap Stainless 1,4301 304 1,4401 316steel

19a Nut Stainless 1,4401 316 1,4401 316steel

20 Motor cable

22 Bolts Stainless 1,4401 316 1,4401 316steel

23 Rubber guard

24 Coupling Stainless 1,4460 329 1,4460 329steel

25 Neck ring PP

26 Neck ring for Stainless 1,4301 304 1,4401 316strainer steel

28 Lock for Stainless 1,4301 304 1,4401 316strainer steel

39 Spring for Stainless 1,4301 304 1,4401 316valve cup steel

70 Valve guide Stainless 1,4301 304 1,4401 316steel

71 Washer Stainless 1,4401 316 1,4401 316steel

72 Wear ring Stainless 1,4301 304 1,4401 316steel

74 Staybolt Stainless 1,4401 316 1,4401 316steel

74a Nut Stainless 1,4401 316 1,4401 316steel

77 Cover plate Stainless 1,4401 316 1,4401 316steel

77a Screw for Stainless 1,4401 316 1,4401 316cover plate steel

78 Nameplate Stainless 1,4401 316 1,4401 316steel

79 Rivet Stainless 1,4401 316 1,4401 316steel

Pos. Description Material Standard N-Version

DIN AISI DIN AISIW.-Nr. W.-Nr.

Pos. Description Material Standard N-Version

DIN AISI DIN AISIW.-Nr. W.-Nr.


Sect

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5



Section 6

Section 6A Submersible Applications



SECTION 6: SUBMERSIBLE APPLICATIONS AND SIZING

6A SUBMERSIBLE APPLICATIONS

• Submersible Sump Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5• Submersible Can Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-9

6B SIZING AND SELECTION EXAMPLES

• Calculation of Submersible Pump and Motor Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12• Installation and Start-Up Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13

6-1


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6

Section 6A Submersible Applications6-2

6A SUBMERSIBLE APPLICATIONSTypical Uses. Submersible pumps are generally “less expensive to purchase, install, operate, and maintain” than thelineshaft turbines. There are several applications where the submersible pump has many advantages such as: (1)extremely deep wells (deep settings) which may present problems with shafting, (2) crooked wells, (3) installationsubjected to surface flooding which may be damaging to electric motors, (4) applications such as booster pumps inlocations that require quiet operation, (5) installations where there is little or no floor space to install the unit, suchas valts and (6) horizontal pipeline booster pumps placed directly in the pipeline where conditions require aminimum amount of excavation or use of land surface. At the same time, there are some uses which do not lendthemselves well to submersible pumps such as: (1) high fluid temperatures, and (2) unusually corrosive or abrasivefluid applications. Most submersible motors can be operated vertically, horizontally, or at any angle provided motordrive shaft is pointed-up.

Typical Submersible pump applications are:

(1) Agricultural (Irrigation)(2) Industrial (Factories)(3) Municipal (Water Supply)(4) Dewatering(5) Inline Boosters(6) Offshore Platforms (7) Oil Industry

The following discussion of typical applications and market segments are intended to familiarize the reader with thebasics regarding the use of submersible pumps. There are many other uses and application which are not discussed.

Agricultural. Agricultural pump installations consist of those applications where water must be pumped fromavailable water sources form domestic, livestock, drainage and irrigation needs. Of these various requirements,the pumping of water for irrigation of crops is the most prominent. It is estimated that there is over 50,000,000irrigated acres in the U.S.

Industry. Submersible pumps and motors are used in industry for water supply pumping and for industrialprocess needs, as well as waste disposal. Water is used as an ingredient in final products, conveyance, processcooling, dilution of wastes, etc. Industrial wastes are normally classified as a physical, chemical, or bacterialpollutant. Each type of pollutant is treated or disposed of in different ways and the remaining “clean” waterrecirculated.

Municipal. In order to attain sanitary living conditions it is necessary to supply potable water and transportwaste (sewage) away from cities to be treated. The water supply required comes from rivers, lakes,groundwater and reclamation. Pumping systems of all types are often located close to residential areas forwater supply or booster purposes. Noise from above ground motors sometimes presents an annoyance.Vandalism often occurs to above ground motors due to there proximity to residential areas. The submersiblemotor represents an alternative method, which is virtually free from the above-mentioned hazards.

Dewatering. Dewatering wells are drilled into a water bearing strata to facilitate construction and/or preventhyrostatic forces from displacing structures in high water table areas. Submersible pumps are convient to usefor dewatering purposes as they can be easily installed, set up and controlled. Similarly mine shafts drilled intowater bearing strata also require pumping to remove water so that mining is possible. Flooding in a mine isalways a constant danger and water levels rising beyond certain levels will cause surface motor failure.Submersible installations aren’t affected by flooding and also require no routine maintenance. It is however,necessary to select the proper corrosion resistant construction material necessary to pump mine water.

In-Line Boosters. The situation often arises in waterworks and industrial practices where the pressure in adelivery main is insufficient to maintain the required rate of flow of water. Installing booster pumpingequipment at a suitable point along the main is often the least expensive method to maintain pressure. Thesubmersible type of in-line booster is housed in a casing or chamber which is, in effect, an enlarged section of


Section 6


the main. The pump is normally suspended horizontally within the pipe to boost the liquid being carried bythe line. A can booster system has also been used to boost pressure. In a can type system, the pump issuspended vertically, with the can typically being constructed below ground.

Offshore Platfroms. Offshore drilling and production platforms require the use of submersible pumps capableof handling highly corrosive sea water. The pumping of sea water requires special materials of construction forboth the pump and motor. Stainless steel construction in generally adequate for these applications. The gradeof stainless steel is highly dependant on water temperature.

Oil Industry Pumping. The secondary recovery of oil from fields which have reached a point of depletion canbe accomplished by injecting water into the oil formation in such a pattern as to create a water drive. Thewater drive forces the remaining oil that is held in the reservoir, to the production wells. Water obtained froma well supply may, in certain cases, can be injected directly to the oil bearing formation. The water obtained isusually obtained from great depths.

Adverse Service Conditions. The condition of the service into which a submersible unit is placed is of majorimportance with respect to performance, service life and reliability. The comments below outline the most commondetrimental service and application issues that require special attention or must be addressed to insure properoperation. It is probable that suitable installation adaptions, alternate selections and/or equipment modifications canbe made to insure satisfactory operation in the unusual applications described. Adaptations and modifications aremost effectively implemented when potential problems are identified and considered early in the design/selectionprocess.

1. Well Development. A new submersible unit should not be used for well development purposes, as rapidperformance deteriation is likely to occur. Complete well development is best accomplished using a test pump priorto installation of the production unit. See Section 1B for a more detailed discussion of the well development process.

2. Effects of Pumping Sand. Submersible pumps are not generally recommended in applications where abrasives aresuspended in the water. The erosive action of sand, silt or other abrasive materials can significantly reduce pumpingcapacity and efficiency. Abrasives wear will directly reduce pump life via bearing wear and indirectly shorten motorlife as a result of transmitted vibration from the worn pump end.

See Section 2D for a more detailed discussion of entrained solids. Submersible Pumps offering all stainless steelconstruction and rubber bearings/seals can perform well in pumping applications at sand concentration levels up to50 ppm.

3. Effects of Air or Gas. Guarantees of hydraulic performance are contingent on pumping clean cool water, free ofair or gas with the pump properly submerged. The presence of gas in the water will affect the hydraulic performance by reduction in capacity and head, which cannot be predicted with accuracy. Thepresence of air or gas in the well will cause the deterioration of materials sooner than under normal conditions. SeeSection 2D for a more detailed discussion of entrained gas.

4. Suction (Intake) and Submergence Requirements. Pumping at a rate that will cause the unit to break suction orcause cavitation will cause pump deterioration. When possible, minimum submergence should be maintainedbetween 5’ and 10’ for sump booster and water well applications respectively, although some installations mayrequire more submergence to satisfy pump NPSH requirements. See Section 2D for a more detailed discussion ofsuction/intake uses based on the specific application (ie. cavitation, vortexing, submergence, etc.).

5. Water Quality, Chemicals and Impurities. Submersible units have proven their ability to satisfactorily handle waterhaving unusual chemical analysis; however, standard construction for most high capacity submersibles are generallydesigned to pump cool potable quality natural waters containing little or no pollutants, gas or solids. See Section 1Afor a more detailed discussion of water quality and chemical impurity issues under the general heading of corrosion.Grundfos utilizes all stainless steel construction, which is immune to many of the detrimental water quality issues atthe concentration levels normally encountered in natural waters.

6-3


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6

6. Well Survey. The installation (well, sump, etc.) should be surveyed with respect to depth, diameter and alignmentto insure/permit installation. In new installations, such a survey may only require a verification of constructionrecords and logs. In installations where historic records are not available and new equipment is required, a “cage”survey should be conducted to determine well depth, diameter and straightness - as necessary. Many wells havemore than one string of casing installed, and frequently the lower sections are smaller in diameter than the surfacecasing. The submersible unit must pass freely into the well. The alignment survey process is discussed in detail inSection 1B.

7. Crooked Wells. A submersible pumping unit will perform better in a crooked well than a line shaft turbine typepump, because the length of those parts containing rotating members is much shorter. When a well is known to becrooked and has not previously accommodated a unit of comparable size, or has been determined to be crookedbased on an alignment survey result (see Section 1B), a “gage” survey should be conducted using a special dummy.

A crooked well gage survey to determine the suitability of a crooked well for submersible applications, is similar tothe AWWA alignment test which utilizes a close tolerance dummy. The submersible gage survey is conducted usinga dummy of the same length and largest diameter as the combined pump and motor unit, the dummy is typicallyconnected to 40-50 feet of pipe of the size as the column pipe to be used. If the assembly can be lowered andremoved from the well to the desired setting depth without binding, the well is suitable for installation of thesubmersible unit.

8. Starting Equipment (Existing/Customer Supplied). The submersible motor is always located below the water levelwhere it is impossible to hear or observe the motor after starting. To avoid troubles encountered with old, used orinadequate starting equipment; the following items should be addressed: (1) adequate fuzing, (2) overload sizing and (3) three leg phase protection - voltage/current balance. See Section 3Cfor a move detailed discussion of starting and control equipment issues.

9. Water Temperature. Submersible motors are cooled by water passing along the exterior of the motor as it entersthe pump intake. Heat internally generated in the motor is transferred to the moving ambient fluid via connectiveheat transfer. When water temperature exceeds 80°F, some consideration should be given to the issue of motorcooling. Most manufactures of canned-hermetically sealed type submersibles are rated for ambient service up to86°F (30°C). Water temperatures up to 100°F can be handled provided fluid velocities can be increased to dissipateheat and/or motor loading can be reduced. A shroud is frequently used to direct flow and increase velocity in warmwater applications.

In general, if water is continually flowing into the pump and past the motor, the motor will operate satisfactory. SeeSection 4B for a more detailed discussion of motor cooling issues.

10. Voltage. Voltage at the motor terminals should be maintained within plus or minus 10% of the motor nameplatevoltage. If there is a 5% voltage drop in the cable, voltage at the surface must not be less than 95% of rated voltage.

11. Load. There are many variables which effect submersible motor operation. It is recommended that the motorsize be selected so that the name plate horsepower will not be exceeded at the design condition. The motor servicefactor horsepower should not be exceeded anywhere on the performance curve.

12. Thrust. Motor thrust ratings should not be exceeded under any condition operation including shut-off.

13. Electrical Characteristics. The system electrical characteristics (voltage, frequency, generator) should be clearlyidentified as these factors have a definite impact on the motor and pump selection. Close attention must be paid todistribution voltage stability and quality, as well as cable voltage drop to insure the minimum required motorterminal voltage is delivered.



Section 6


Submersible Sump Pumps (Vertical - Clearwater)Pump Considerations. The versatility of the submersible pump in water well service is equally advantages whenadapted for sump/wet pit applications. The greatest advantages associated with submersible pumping equipment forsuch applications are; (1) vertical mounting of pump and motor, submerged in the fluid, affording minimal floorspace, and (2) minimal foundation/support requirements. The primary disadvantage is the greater pit depth requiredto accommodate the submersible motor.

The use of submersible pumps in sump/wet pit applications will generally require the use of a cooling shroud toinsure proper motor cooling. Some submersible motor manufactures do not require a cooling shroud for cold waterapplications (below 50°F); however, the use of a cooling shroud is recommended as it improves cooling andhydraulic performance in wet pit applications. Motor cooling shrouds can be purchased commercially or constructedin expensively as described in Section 4B. While adapting a submersible pump to open sump service is relativelyeasy, consideration must be given to the design of the sump to ensure proper pump performance.

General Sump Requirements. A key factor in good sump design is the ability of the sump intake channel/pipingto supply an evenly distributed flow of water to the pump suction intake. An uneven flow is characterized bystrong local currents and favors the formation of vortices, under certain submergence conditions vortices canintroduce air into the pump with a resulting loss of pump performance, noise and vibration.

The ideal intake design is a direct channel going directly to the pump. Any turn or obstruction cause eddy currentsand tend to initiate deep-cored vortices. General design rules and guideline standards for clear water (wet pit)sumps are published by the Hydraulic Institute and should be consulted for complex design projects. The standardsare particularly applicable to vertical turbine pumps with a suction bell intake. The same rules apply to submersibleapplications; however, the diameter of the motor shroud should be substituted for the suction bell diameter wherespecified in other references. The focus of this discussion will center on sump design to accommodate pumps withindividual discharge capacities of 3,000 gpm or less. The suggestions presented below are offered as generalguidelines and may not represent a optimized system.

Sump Design for Small Pumps. The ideal pump sump is rectangular, although circular sumps can be utilizedsuccessfully when properly designed. Stream lining should be used to reduce the trail of alternating vortices in thewake of the pump or other obstuctions in the flow stream.

Proper submergence is one of the most important factors in the sump design process. Many deficiencies associatedwith poor design can be improved with increased submergence. Unfortunately, the trade-off associated withincreasing submergence is a more expensive sump/wet pit construction. Minimum submergence requirements arenormally provided by the pump manufacture; however, Section 2D can be used to estimate submergence when theimpeller eye diameter (cross sectional area) and maximum flow is known. In the absence of any information, use aminimum submergence of 1.5’ above intake and add one additional foot of submergence for each foot per second(fps) in approach channel/piping velocity. The submergence is in addition to any positive NPSH submergenceneeds of the pump at maximum design flow.

Other factors pertinent to the design of small sump/wet wells are listed as follows:

1. Inlet Opening (pit type sumps). The inlet to the sump should be below the minimum water level and as faraway from the pump as the sump design will allow. The inflow should not jet directly into the pump inlet orenter the pit in such a way as to cause rotation of the liquid in the pit. Distribution nozzles can be added toprevent jetting and baffles added to prevent rotation. The introduction of water to the sump, through free fallshould be avoided whenever possible.

2. Sump Volume (pit type sumps). The usable pit volume should equal or exceed the maximum capacity to bepumped in two minutes. If the pumps are to be controlled by float switch, the pit should be large enough toallow no more than 3 or 4 starts per hour per pump. In this way the size of the pit should be large enough toprevent inflow turbulence and to assure a reasonable operating life for the stating equipment.

3. Minimum Liquid Level. The minimum liquid level should be sufficient to satisfy submergence requirement forthe particular pump design.

6-5

Correction of Existing Sumps. Commonly employed corrective measures to prevent vortexing in existing sumps,include but are not limited to; (1) increasing submergence, (2) reducing inlet and /or approach channel velocity, (3)adding baffling to change flow direction and speed, and (4) relocating pump(s) position within the sump.

Summary Requirements - Single Pump. The following guideline should be used in the design of a single pumpsump system.:

1. Back wall distance to centerline of pump: .75 - 1.5D2. Side wall distance to centerline of pump: 1.0 - 2.0D3. Bottom clearance: .33 - .67D4. Distance from sump inlet to pump: 3 - 4D (min.)/7-80 (optimum)5. Intake approach velocity: 2 - 3 fps6. Submergence: Per manufacture recommendations (approximated in the absence of manufacture data)

Note: Increasing submergence and/or lowering intake velocity are good insurance against vortexing. Increaseminimum submergence by 25-50% for circular sumps.


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6


Figure 6-1: Typical Single Pump (< 3000 gpm) - Sump Application Suggestions

1D - 2D

ChannelVelocity1-3 fps

D D

2D(minimum)

.75 - 1.5 D

3 - 4D*(minimum)

2 - 4D Range

.75D1.5D

H

.33 - .67D

1 - 2D

D

Avg. SumpVelocity

Intake Velocity2-6 fps

Summary Requirements - Multiple Pumps. Ideally, each pump should be provided with its own approachchannel (cell) within the sump. Often it is not feasible to provide separate approach cells, under thesecircumstances, each pump should be separated as shown in Figure 6-2. Water should not flow past one pump toreach another. If pumps must be placed in the line of flow, it may be necessary to construct open front approachcells as discussed under the ideal case.

* 3 - 4D if sump bottom is level with feeding pipe or channel.


Section 6

Section 6A Submersible Applications 6-7

The design guidelines for multiple pump in a single large sump are:

1. Locate pumps in line running perpendicular to the approach flow2. Spacing between pump centerlines: 2 - 4D (when individual pump bays/cells are impractical)3. Back wall and bottom clearance, as well as submergence same as that of a single pump4. Each pump should have a capacity of less than 3000 gpm

Refer to Figure 6-2 for design suggestions for various configurations of multiple pumps in a common sump, oftenencountered in submersible applications.

Figure 6-2: Typical Multiple Pump (< 3000 gpm) - Sump Application Suggestions

.75 - 1.5 D

1 - 2D

2D - 4D

1 - 2.5D

1 - 2D 2 - 4D

Velocity = 1-3 fps

H = Submergence

Center LineNext Unit

D

.5 - 2D

Figure 6-3: Typical Submersible Wet Well Illustration

Two or More Pumps in One Sumpwith Individual Approach Cells

Two or More Pumps in One Sumpwithout Individual Approach Cells

Plan View Elevation


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6


Figure 6-4: Multiple Pumps in a Common Sump - Frequently Encountered Application

S

B

Vc = 1 - 3 fpsS = 2 - 4DB = .75 - 1.5DD

DVpW

Y P

Baffles, grating or strainer should be introduced across inlet channel at beginning of maximum width section.

Vc = 1 - 3 fpsVe = 2-6 fpsA = 8D or greater

D

A

VeVc

Alt.

W = 5D or more, orV1 = 0.2 fps or less andY = Same as chart to leftS = Is greater than 4D

D

V1

W

S Y

NotRecommended

Unless...

Always AvoidIn-Line Flow When Possible

Y = 3 - 4DMAX α = 15°(10° pref.)

D

Y

αVe =2 - 6 fps

Min. 2F

V up to 8 fps

TurningValve

No MotorShroud Normally

Required

F

Beam Selection for Pumps Spanning Sumps. The following table gives the permissible load on “I” beams whenused as pump foundations spanning sumps:

Table 6-1: Permissible “I - Beam” Loads in pounds (#)

Span Beam Size

(ft.) 4”- 7.7 # 5”- 10.0 # 6”- 12.5 # 7”- 15.3 # 8”- 18.4 # 10”- 25.4 # 12”- 31.8 #

3 6625 10570 15960 22960 279504 4560 7960 11950 17450 23440 39900 548805 3360 5840 8900 13940 18910 32375 478506 2540 4590 7390 10500 14600 26850 398207 2150 3450 5820 8350 12400 21400 315508 1680 3020 4620 7290 10150 18700 273509 1320 2400 3720 5850 8800 15100 2410010 1920 3260 4870 7150 13800 2368011 2640 4260 5790 11350 1845012 3520 5300 10200 15100

Notes: 1. Permissible loads in the above table are based on laterally unsupported beams with concentrated loads.If beams are supported laterally these loads may be increased.

2. Concrete foundations and footings for I-beam foundations will vary with soil conditions, but in no caseshould be bearing pressure on the soil exceed 2000 pounds per square foot.

3. To calculate total load on foundation, add the weights of all component parts, including dischargeelbow, column pipe and cable, plus the weight of water in column. The load on each beam will beone-half of the total load found in this manner. Permissible loads shown in table are based on load oneach beam or half the total load on foundation.

W/P Y Vp

1.0 3D 1

1.5 5D 2

2.5 8D 4

4.0 10D 6

10.0 15D 8

Submersible Can Pumps (Vertical)General. Providing the required net positive suction head (NPSH) for horizontal pumps often necessitates locatingthe unit in a pit below floor level, which can be very costly. Maintenance is more difficult and the possibility ofmotor damage is introduced should the pit be subject to flooding. The vertical submersible can pump is often usedto overcome these disadvantages and when it is not desirable to have a surface motor as result of noise orvandalism, or horizontal space limitations exist. The can pump can be operated under positive pressure or undersubmergence pressure, in the same manner as a sump applications.

In a submersible can booster system, the pump and is in a fabricated steel can which forms a suction well (wetwell). The can is furnished in a length suitable for providing the depth to insure the dimensional requirements ofthe submersible unit are met. The column assembly is supplied in the length necessary to place the intake of thepump assembly at the required elevation in the can for meeting the pumps NPSH requirement. The pump suction(intake) is flooded; therefore, there is no need for equipment.

The T-Head type of construction shown in Figure 6-5 is most popular due to the inline arrangement of suction anddischarge connections for surface systems. Can is normally fitted with a standard ANSI flange and sealed by boltingdirectly to the discharge elbow can mating flange, thereby forming a unitized sealed suction chamber. The can isinstalled below the floor level, supporting the pump and motor suspended from the discharge elbow can matingflange.

The suction and discharge piping should be supported and aligned with the pump /can inlets and outlets to avoidunnecessary stress concentrations at connection points. In order to insure correct alignment of all pumpcomponents within the can, the can must be properly supported and leveled to prevent distortion. The can flangemust be attached and supported in such a manner to adequately carry the entire weight of the pumping unit,without appreciable deflection.

The principal use of the canned booster system is for high pressure boosting of water for various processapplications such as filtration and injection. In such applications, most manufactures allow for a vertical andhorizontal configuration. Horizontal applications are discussed separately latter in this section. Can pumps are alsocommonly used in fluid distribution networks for booster service, since suction inlets and pump dischargeconnections can be economically tied to existing pipe lines. The can suction inlet can be configured to fit theelevation of the existing underground pipeline.

Design Considerations. When designing a can pump system, the net differential pressure between the can intakeand the pump discharge flange is the issue. All of the head losses at the suction inlet, barrel, cooling shroud (wherehead losses within the can; however, the following guidelines are offered.

Suction Velocity ≤ 8 ft./sec. Cooling Shroud ≤ 6 ft./sec.Barrel Velocity ≤ 6 ft./sec. Discharge Velocity ≤ 12 ft./sec.

Overall efficiency and poor/insufficient NPSH problems can be improved by reducing the above listed velocities byenlarging the suction, discharge and barrel sizes. The fluid velocity past the motor should be no less than 0.5 ft./sec.When the flow rates are 3000 gpm or less, the can diameters should be 2” - 10” larger than the largest submersiblecomponent (pump, motor or cooling shroud). A value of 2”, 4” and 6” is recommended for flow rates up to 100,500 and 1000 gpm respectively. See Table 6-2 for typical can pump capacities.

Relative velocity between two different diameters can be calculated using the following formula:

where;

V = Velocity in fps ID = Inside diameter of largest circular section in inchesQ = flow in gpm OD = Outside diameter of smallest circular section in inches


Section 6


V = Q / 2.4 (ID2 - OD2)


Sect

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Table: 6-2: Pump Barrel vs Pump Size - Typical Allowable Capacity in gpm

* Nom. Sub Nominal Barrel Size (in.)EquipmentDiameter 8 10 12 14 16 18 20 24 30

6 250 450 725 10408 240 628 925 13509 160 423 730 1120 155010 205 470 900 1380 185011 410 840 1320 178012 660 1150 1690 295014 325 810 1350 262016 370 900 2180 4515

* Motor, pump or cooling shroud diameter, whichever is greater

Physical data for can pump suction barrels are listed in Table 6-3.

Submergence. The manufactures submergence requirements should be followed where the can is not under positivepressure. The can should be vented as entrained free gas can be trapped at the highest point in the can.Accumulated gas or vapor can significantly reduce the liquid head available to meet the pumps NPSH requirements.

Inlet Location & Cooling. When the suction inlet of the can pump is in the barrel, special attention must be given tothe inlet location relative to the pump suction intake, as hydraulic performance and motor cooling problems canresult. If the suction inlet is too close to the intake of the pump, the pump may develop noise and vibration due tothe vortex generated by the turbulent flow at the inlet. Figure 6-5 illustrates the general guidelines for inlet location,provided flow conditions are uniform and stable upstream form the suction.

Motor cooling is essential for proper submersible operation, and for this reason close attention must be paid to thisissue. In general, the use of a motor cooling shroud is recommended anytime fluid enters the can from any locationother than from below the motor. Under certain circumstances, where the pumped fluid temperature is less than68°F (20°C), it may be possible to operate the motor without a cooling shroud regardless of can intake position.Specific submersible motor cooling issues are discussed in Section 4B.

In-Line Submersible Can Pumps. The in-line submersible can configurations offers many of the same advantagesas the vertical can system. It is ideal for locations where a horizontal space can be utilized efficiently to house apump. The horizontal can system is extremely flexible, as no wet well is required. Typical applications includeindustrial high pressure packaged filtration systems, where space is at a premium. In addition, the inline can pumpcan be easily retrofitted into existing horizontal or vertical piping sections of sufficient length.

Most vertical multi-stage submersible pump ends can be operated in the horizontal position however, not allsubmersible motors have the same functionality. A slight reduction in pump and motor service life is generallyassociated with horizontal installations compared to vertical configurations, as a result of a bearing load placed onradial guide bearings, see Figure 6-6.

The selection and design criteria for a horizontal can application, is principally the same as that for a verticalapplication. The pump intake should be under positive pressure at start-up; however, it may be possible to pull asuction pressure downstream of the installation, provided NPSH requirements can be met.

Motor cooling is less of an issue in such applications as the pumped flow (cooling flow) must pass over the motorbefore being discharge upstream. The motor and pump must be supported in accordance with the manufacturesrecommendations and centered within the can barrel to insure proper operation.


Section 6


Table 6-3: Typical Standard Steel Barrel Data

Low Pressure Barrels (1) High Pressure Barrels (1)Barrel Wall Weights (lbs.) Pressure Wall Weights (lbs.) Pressure

Diameter Thk. First Addl Rating Thk. First Addl RatingO.D. (in.) (ft.) (ft.) psi (2) (in.) (ft.) (ft.) psi (2)8 5/8 .277 107 25 275 .500 171 44 72010 3/4 .279 146 31 275 .500 282 55 72012 3/4 .330 186 44 275 .500 374 65 720

14 .250 262 37 275 .500 440 72 72016 .250 330 42 275 .500 639 83 71318 .250 381 47 275 .500 733 94 63220 .250 500 53 275 .500 831 104 56724 .250 637 63 234 .500 1150 126 47130 .250 987 79 154 .500 1293 158 275

(1) Barrel flanges are 150 lb. For all low pressure barrels and for high pressure barrels 30” and larger. Highpressure barrels 8” through 24” have 300 lb. Flanges. A hydrotest at 150% of pressure rating is standard.

(2) Rating is bases on zero corrosion allowance and normal stresses.

Figure 6-5: Typical In-Line Submersible Applications

Motor Pump Inlet


Sect

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Section 6B Sizing and Selection Examples6-12

6B SIZING AND SELECTION EXAMPLESCalculation of Submersible and Motor SizeThe following procedure shows the calculation of pump and motor sizes. This is how to calculate the approximatepump performance and motor power output.

Table 6-4: Pump & Motor Sizing Example

Step Action

1 Refer to Table 5.2 for all values per stage.• Choose nearest pump size (gpm) for required flow rate• required head (ft)• local frequency (Hz)

2 Find head per stage (H) at the required flow on the single-stage performance Table 5-2.Subsequently find the number of stages by dividing the required head by head per stage (H).Choose the nearest number of stages above this figure.

3 Calculate the head: HT = H x number of stages.Find the pressure loss (Hloss) at the required flow rate on the single-stage performance curve.

4 Find the preliminary power requirement at the required flow rate on Table 5-2.Calculate the total power requirement: power requirement per stage x number of stages.Choose the nearest motor size above this figure.

5 Read the corrected speed (n1) on the motor performance characteristics curves based on the motorload.Corrected speed is found in the Grundfos or Franklin motor specification sheets for the calculated hp.NOTE: The motor performance characteristics curves are specific for the various motors.

6 Calculate the corrected pump performance (Q1 and H1) and the power requirement (P21) according tothe equations shown.

7 Read again the motor speed on the motor performance characteristics curves based on the correctedpower requirement (P21).NOTE: If the deviation from the corrected motor speed (step 5) exceeds 10 rpm, recalculate (step 3). 10 rpm corresponds to approx. 1% change of the load.

The equations used for the calculation of correctedpump performance (Q1 and H1) and powerrequirement (P21).

Table 6-5: Pump Performance Equations

H1 = (H – H1) x ( )n1

n

2

P21 = P2 x ( )n1

n

3

Q1 = Q x n1

n

The equations used for the calculation of correctedpump performance efficiency and overall efficiency.

Table 6-6: Pump Performance Equations

ηp =Q1 x H1

P21 x 367

ηp = ηp x ηm

ηtotal =Q1 x H1

P1 x 367


Section 6

Section 6B Sizing and Selection Examples 6-13

Installation RulesIn order to ensure the cooling and lubrication ofbearings and neck rings the Large SP pumpshould be started only when it is completelysubmerged in the liquid.

The Large SP pump is suitable for verticalhorizontal installation. The pump should neverbe installed below the horizontal plane (shadedarea in drawing).

The pump should be installed in such a way thatthe water level is never below the suctioninterconnector of the pump during operation.

It is recommended to use the Grundfos controlunit type CU 3 or another type of dry-runningprotection. Also, a flow sleeve is recommendedfor proper motor cooling in all horizontalinstallations. All Grundfos submersible pumpsand motors are designed for continuousoperation.

Start-Up RulesThe Large SP pump should be started only whenthe suction interconnector is completelysubmerged in the liquid.

When the pump has been connected correctly and it is submerged in the liquid to be pumped, it should be startedwith the discharge valve closed off to approximately 1/3 of its maximum volume of water.

If there are impurities in the water, the valve should be opened gradually as the water becomes clearer. The pumpshould not be stopped until the water is completely clean, as otherwise the valve may choke up.

As the valve is being opened, the drawdown of the water level should be checked to ensure that the pump alwaysremains submerged.

The dynamic water level should always be above the suction interconnector of the pump. See Figure 6-7.

Figure 6-6: Pumping Orientation

Figure 6-7: Pump Installation Depth

Code Description

L1 Min. installation depth below dynamic water level.Min. 1 metre is recommended.

L2 Depth to dynamic water level.

L3 Depth to static water level.

L4 Drawdown. This is the difference between the dynamic andthe static water levels.

L5 Installation depth.


Sect

ion

6

To ensure long and safe pump life it is important that the following rules be followed.

Minimum inlet pressure is indicated in the NPSH-curves in the single-stage curves in Performance. The minimumsafety margin of the NPSH-curves should always be 1.0 mWC.

To ensure sufficient cooling of the motor, the pump must not be run continuously at a flow rate lower than 0.1 xnominal flow rate.

The pump should not be operated against a closed valve for more than 30 seconds as this may heat the pumpedliquid and damage both pump and motor.

Due to the risk of upthrust and cavitation the pump must not run continuously at a flow rate higher than 1.3 xnominal flow rate.

To ensure cooling and lubrication of bearings and seal rings, the pump must not be started until it is fullysubmerged in the liquid.

The pump must be installed in such a way that it does not lower the water level below the pump inlet.

It is recommended to use the Grundfos type CU 3 control unit or some other type of dry-running protection.

The maximum installation depth below water level is stated in the table below.

Section 6B Sizing and Selection Examples6-14

Table 6-7: Max. Motor Depth

Motor type Depth below water level

(m) (bar) (MPa)

*MS 402 150 15 1.5*MS 4000 600 60 6*MS 6000 600 60 6Franklin 350 35 3.5Mercury 350 35 3.5

*MS - Grundfos Motor


Section 7

Section 7A Technical Appendices



SECTION 7: TECHNICAL APPENDICES AND REFERENCE LIST

7A TABLES

• Pipe Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2• ANSI Flange Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10• Friction Loss in Pipe/Fittings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-12• Equivalent Pipe Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-23• Pipe Flow Estimating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-24• Unit Conversion Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-27

7B REFERENCE LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-31

7-1


Sect

ion

7

Section 7A Technical Appendices7-2

Tab

le 7

-1:

Sta

nd

ard

T &

C S

tee

l P

ipe

Da

ta C

om

mo

nly

Use

d f

or

Pu

mp

ing

Ap

plic

ati

on

s (C

olu

mn

/Ris

er,

Su

cti

on

an

d D

isc

ha

rge

Pip

e)

No

m.

Dia

met

erW

all

Pip

e W

t.C

ou

pli

ngs

Int.

Pres

sure

Rat

ings

(ps

i)M

ax.

Size

OD

IDT

hk

.T

&C

/PE

Sch

.T

hre

ads

OD

Len

gth

Cp

lg.

Wt.

Vo

l.W

ork

Bu

rst

Sett

ing

(in

.)(i

n.)

(in

.)(i

n.)

(lb

s./f

t.)

No

.p

er i

nch

(in

.)(i

n.)

(lb

s.)

(gal

./ft

.)P

res.

Pre

s.(f

t.)

1/8

.405

.270

.068

0.25

/*40

27.5

627/

8.0

3.0

0316

8010

,000

-1/4

.540

.364

.088

0.42

/*40

18.6

851

.04

.005

1630

9,80

0-

3/8

.675

.494

.091

0.57

/*40

18.8

481

1/8

.07

.010

1350

8,08

0-

1/2

.840

.623

.109

0.90

/0.8

940

141.

021

3/8

.12

.016

1290

7,78

0-

3/4

1.05

.824

.113

1.30

/1.1

340

141.

281

5/8

.21

.028

1080

6,46

0-

11.

321.

05.1

341.

80/1

.68

4011

1/2

1.58

1 7/

8.3

5.0

4510

106,

070

-1 1

/41.

661.

38.1

402.

30/2

.27

4011

1/2

1.95

2 1/

8.5

5.0

7884

05,

060

-1 1

/21.

901.

61.1

452.

75/2

.72

4011

1/2

2.22

2 3/

8.7

6.1

0676

04,

580

-2

2.38

2.07

.154

3.75

/3.6

540

11 1

/22.

712

5/8

1.23

.174

650

3,89

012

502 1

/22.

882.

47.2

045.

83/5

.79

408

3.28

2 7/

81.

76.2

4970

04,

240

1250

33.

503.

07.2

177.

70/7

.58

408

3.95

3 1/

82.

55.3

8462

03,

700

1250

3 1

/24.

003.

55.2

269.

21/9

.11

408

4.59

3 5/

84.

33.5

1456

03,

390

-4*

4.50

4.03

.237

11.0

/10.

840

85.

043

5/8

5.41

.661

520

3,16

011

005*

5.56

5.05

.259

15.0

/14.

640

86.

304

1/8

10.8

1.04

460

2,78

011

006

6.63

6.07

.280

19.5

/19.

040

87.

364

5/8

15.8

1.50

420

2,53

010

008*

8.63

8.07

.277

25.6

/24.

730

89.

426

1/8

26.6

2.65

320

1,92

090

08

8.63

7.98

.322

29.4

/28.

640

89.

426

1/8

26.6

2.60

370

2,24

0-

10*

10.7

510

.19

.279

32.8

/30.

1-

811

.86

1/8

33.9

4.24

255

1,55

080

010

10.7

510

.14

.307

34.2

/32.

230

811

.86

1/8

33.9

4.19

280

1,71

0-

10

10.7

510

.02

.366

41.9

/40.

540

811

.86

1/8

33.9

4.10

340

2,04

0-

12*

12.7

512

.09

.330

45.5

/43.

830

814

.06

1/8

43.8

5.96

250

1,55

070

012

12.7

512

.00

.375

51.1

/49.

6ST

D8

14.0

6 1/

843

.85.

8729

01,

760

-14*

14.0

013

.25

.375

*/54

.630

--

--

7.16

270

1,61

070

016*

16.0

015

.25

.375

*/62

.630

--

--

9.49

230

1,41

0-

Note

s:1.

Pip

e an

d C

ouplin

g (2

1/2

” -

12”)

can

be

furn

ished

with

8 p

itch s

trai

ght th

read

s or

NPT tap

er thre

ads.

Tap

ered

thre

ad b

eing

the

most

popula

r fo

r su

bm

ersi

ble

colu

mn/r

iser

applic

atio

ns

as they

are

more

res

ista

nt ag

ainst

unsc

rew

ing.

2.Pip

ing

grea

ter

than

12”

dia

met

er is

norm

ally

fla

nge

d.

3.Conve

rsio

n F

orm

ula

: 1

” = 2

5.4

mm

, 1

.0 lb. = 0

.454

kg

4.W

ork

ing

pre

ssure

bas

ed o

n a

SF

= 6

, an

d a

ten

sile

yie

ld s

tren

gth o

f 30

,000

psi

(A-5

3, g

rade

A)

5.Se

lect

colu

mn (

dro

p/r

iser

) pip

e si

ze to p

rovi

de

an u

pw

ard f

low

vel

oci

ty in the

range

of

4.0

- 15

.0 f

ps.

A v

alue

of

5 fp

s is

rec

om

men

ded

and

can b

e ca

lcula

ted u

sing

the

follo

win

g fo

rmula

:

* Confo

rms

to A

NSI

B58

.1 (

AWW

A E

- 1

01)

Vel

oci

ty =

gp

m (

.410)

/ (I

D)


Section 7

Section 7A Technical Appendices 7-3

Table 7-2: Pipe Data for commonly used Mild Steel & Stainless Steel - Standard and Line Pipe

Nom.Size

OD(in.)

APIStd.

IDENTIFICATION

Standard(STD)

X-Strong(XS)

Sch.Num.

WallThk.(in.)

Avg.ID

(in.)

Int.Area

(sq. in.)

PipeWt.

(lbs./ft.)

Int.Vol.

(gal./ft.)

WorkPres.

(Kpsi)

Sy = 30 Kpsi Tensile Yield

BurstPres.

(Kpsi)

CollapsePres.

(Kpsi)1/8(.405) 5L

5LSTDXS

10S4080

0.0490.0680.095

0.3070.2690.215

0.0740.0560.036

.1863

.2447

.3145

.0038

.003

.0019

1.201.682.33

7.3010.114.1

10.815.822.6

1/4(.540) 5L

5LSTDXS

10S4080

0.0650.0880.119

0.4100.3640.302

0.1320.1040.071

.3297

.4248

.5351

.0069

.0054

.0037

1.211.632.20

7.229.8013.2

10.815.321.2

3/8(.675) 5L

5LSTDXS

10S4080

0.0650.0910.126

0.5450.4930.423

0.2330.1900.140

.4235

.5676

.7388

.0121

.0099

.0073

1.001.351.86

5.808.0811.2

8.3312.417.7

1/2(.840)

5L5L

STDXS

5S10S4080

0.0650.0830.1090.147

0.7100.6740.6220.546

0.3950.3560.3030.234

.5383

.6710

.85101.088

.0206

.0185

.0158

.0122

0.771.001.291.75

4.645.937.7810.5

6.3610.211.716.5

3/4(1.050)

5L5L

STDXS

5S10S4080

0.0650.0830.1130.154

0.9200.8840.8240.742

0.6640.6130.5330.432

.6838

.85721.1311.474

.0345

.0319

.0277

.0225

0.620.941.081.46

3.715.636.468.80

4.806.569.4813.5

1(1.315)

5L5L

STDXS

5S10S4080

0.0650.1090.1330.179

1.1851.0971.0490.957

1.1020.9450.8640.719

.86781.4041.6792.172

.0573

.0491

.0449

.0374

0.490.831.011.36

2.964.976.078.17

3.446.988.8512.5

1 1/4(1.660)

5L5L

STDXS

5S10S4080

0.0650.1090.1400.191

1.5301.4421.3801.278

1.8381.6331.4951.282

1.1071.8062.2732.997

.0955

.0848

.0777

.0666

0.390.650.841.15

2.353.945.066.90

2.415.217.0910.3

1 1/2(1.900)

5L5L

STDXS

5S10S4080

0.0650.1090.1450.200

1.7701.6821.6101.500

2.4602.2222.0351.767

1.2742.0852.7183.631

.1284

.1154

.1058

.0918

0.340.570.761.05

2.053.444.586.31

1.894.286.259.27

2(2.375)

5L 5LX

5L 5LX5L 5LX

STDXS

5S10S4080

0.0650.1090.1540.218

2.2452.1572.0671.939

3.9583.6543.3552.952

1.6042.6383.6535.022

.2056

.1898

.1743

.1534

0.270.460.650.92

1.642.753.895.51

1.165.007.811.23

2 1/2(2.875)

5L 5LX

5L 5LX5L 5LX

STDXS

5S10S4080

0.0830.1200.2030.276

2.7092.6352.4692.323

5.7635.4534.7874.238

2.4753.5315.7937.661

.2994

.2833

.2487

.2202

0.280.420.700.96

1.732.504.245.76

1.262.615.638.33

3(3.500)

5L 5LX

5L 5LX5L 5LX

STDXS

5S10s4080

0.0830.1200.2160.300

3.3343.2603.0682.900

8.7308.3467.3926.605

3.0294.3327.57610.25

.4562

.4336

.3840

.3431

0.230.340.620.85

1.422.063.705.14

0.741.894.807.19

3 1/2(4.000)

5L 5LX

5L 5LX5L 5LX

STDXS

5S10S4080

0.0830.1200.2260.318

3.8343.7603.5483.364

11.5411.109.8878.888

3.4674.9609.11012.51

.5997

.5768

.5136

.4617

0.200.300.560.79

1.241.803.394.77

0.550.164.176.56

4(4.500)

5L 5LX

5L 5LX5L 5LX

STDXS

5S10S4080

0.0830.1200.2370.337

4.3344.2604.0263.826

14.7514.2512.7311.50

3.9155.61310.7914.98

.7664

.7404

.6613

.5972

0.180.260.520.75

1.101.603.164.49

0.351.053.756.15

5(5.563)

5L5L

STDXS

5S10S4080

0.1090.1340.2580.375

5.3455.2955.0474.813

22.4322.0220.0018.19

6.3497.77014.6220.78

1.1661.1441.039.9449

0.190.240.460.67

1.171.442.784.04

0.480.853.135.32


Sect

ion

7


Table 7-2: Pipe Data for commonly used Mild Steel & Stainless Steel - Standard and Line Pipe (cont.)

Nom.Size

OD(in.)

APIStd.

IDENTIFICATION

Standard(STD)

X-Strong(XS)

Sch.Num.

WallThk.(in.)

Avg.ID

(in.)

Int.Area

(sq. in.)

PipeWt.

(lbs./ft.)

Int.Vol.

(gal./ft.)

WorkPres.

(Kpsi)


BurstPres.

(Kpsi)

CollapsePres.

(Kpsi)6(6.625)

5L 5LX

5L 5LX5L 5LX

STDXS

5S10S4080

0.1090.1340.2800.432

6.4076.3576.0655.761

32.2431.7428.8926.07

7.5859.28918.9728.57

1.67481.64881.50081.3541

0.160.200.420.65

1.001.212.533.91

0.250.482.715.11

8(8.625)

5L 5LX5L 5LX5L 5LX5L 5LX5L 5LX

STD

XS

5S10S2030406080

0.1090.1480.2500.2770.3220.4060.500

8.4078.3298.1258.0717.9817.8137.625

55.5154.4851.8551.1650.0347.9445.66

9.91413.4022.3624.7028.5535.6443.39

2.88362.83042.69342.65772.59882.49022.3721

0.120.170.290.320.370.470.58

0.731.011.741.922.242.823.48

0.100.301.361.672.193.244.38

10(10.750)

5L 5LX5L 5LX5L 5LX5L 5LX

STDXS

5S10S2030406080S*80

0.1340.1650.2500.3070.3650.5000.5000.594

10.48210.42010.25010.13610.0209.7509.7509.562

86.2985.2782.5180.6978.8574.6674.6671.81

15.1918.7028.0432.2440.4854.7454.7464.33

4.48114.42994.28654.19174.09633.87853.87853.7304

0.120.150.230.280.340.460.460.55

0.750.921.391.712.042.792.793.31

0.100.200.741.261.893.133.134.07

12(12.750)

5L 5LX5L 5LX5L 5LX

5LX5L 5LX

5L 5LX5L 5lX

STD

XS

5S10S2030

40S*40

80S*6080

0.1560.1800.2500.3300.3750.3750.4060.5000.5000.5620.688

12.43812.39012.25012.09012.00012.00011.93811.75011.75011.62611.374

121.50120.56117.86114.80113.09113.09111.93108.43108.43106.16101.60

22.1824.2033.3843.7749.5649.5653.5356.7156.7173.1688.51

6.34346.20006.12255.96365.87525.87525.81465.63295.63295.51475.2782

0.120.140.190.250.290.290.320.390.390.440.54

0.730.851.171.551.761.761.912.352.352.643.24

0.100.160.410.951.361.361.682.402.402.923.96

14(14.000) 5L 5LX

5LX5L 5LX5L 5LX5L 5LX

5L 5LX

STDXS

5S10S*102030

6080

0.1560.1880.2100.3120.3750.5000.5940.750

13.68813.62413.58013.37613.25013.00012.81212.500

147.15145.78144.84140.52137.88132.73128.92122.72

-27.7336.7145.6854.5772.0984.91106.1

-7.57307.52427.29877.16296.8956.69726.3750

0.110.130.150.220.270.360.420.53

6.680.810.901.341.612.142.543.21

0.800.130.200.641.162.092.723.86

16(16.000) 5L 5LX


STDXS

5S10S*102030406080

0.1650.1880.2500.3120.3750.5000.6560.844

15.67015.62415.50015.37615.25015.00014.68814.312

192.85191.72188.69185.68182.65176.71169.44160.88

-35.7642.0552.3662.5882.77107.5136.5

-9.5969.80229.64479.48859.18008.80218.4321

0.100.110.150.190.230.310.470.52

0.620.710.941.171.411.872.463.16

0.600.100.250.480.741.573.243.76

18(18.000) 5L 5LX

5L 5LX5L 5LX5L 5LX5L 5LX5L 5LX5L 5LX5L 5LX

STD

XS

5S10S*1020

30

406080

0.1650.1880.2500.3120.3750.4380.5000.5620.7500.938

17.67017.62417.50017.37617.25017.12417.00016.87616.50016.124

245.22243.95240.53237.13233.71230.30226.98223.68213.82204.19

-35.7647.3959.0370.5982.0693.45104.8138.2170.8

-12.67212.49512.31712.14111.96511.79111.61811.27510.607

0.090.100.130.170.200.240.270.310.410.52

0.550.630.831.041.251.461.661.872.503.13

0.540.600.170.300.560.851.161.572.613.76


Section 7


Table 7-2: Pipe Data for commonly used Mild Steel & Stainless Steel - Standard and Line Pipe (cont.)

Nom.Size

OD(in.)

APIStd.

IDENTIFICATION

Standard(STD)

X-Strong(XS)

Sch.Num.

WallThk.(in.)

Avg.ID

(in.)

Int.Area

(sq. in.)

PipeWt.

(lbs./ft.)

Int.Vol.

(gal./ft.)

WorkPres.

(Kpsi)


BurstPres.

(Kpsi)

CollapsePres.

(Kpsi)20(20.000) 5L 5LX

5L 5LX5L 5LX

5L 5LX

STDXS

5S10S*102030406080

0.1880.2180.2500.3750.5000.5940.8121.031

19.62419.56419.50019.25019.00018.81218.37517.938

302.46300.61293.65291.04283.53277.95265.21252.72

39.7846.2752.7378.60104.1122.9166.4208.9

15.71215.61315.51415.11914.72914.43913.77713.128

0.090.100.120.190.250.300.400.51

0.560.650.751.121.501.782.433.09

0.440.800.130.410.951.472.513.65

24(24.000) 5L 5LX


STDXS

5S10S*20

30406080

0.2180.2500.3750.5000.5620.6880.9691.219

23.56423.50023.25023.00022.87622.62422.06221.562

436.10433.74424.56415.48411.01402.00382.28365.15

-63.4194.62125.5140.8171.2238.1296.4

-22.53222.05521.58321.35120.88319.85918.969

0.090.100.160.200.230.280.400.50

0.550.630.941.251.401.722.423.05

0.440.600.250.560.741.262.513.55

30(30.000)


STDXS

5S10

2030

0.2500.3120.3750.5000.625

29.50029.37629.25029.00028.750

683.49677.76671.96660.52649.18

79.4398.93118.7157.5196.1

35.50635.20834.90734.31333.724

0.080.100.130.160.20

0.500.620.751.001.25

0.310.600.100.300.56

36(36.000)


STDXS

10

203040

0.3120.3750.5000.6250.750

35.37635.25035.00034.75034.500

982.90975.91962.11948.42934.82

118.9142.7189.6236.1282.4

51.05950.70049.87049.26848.562

0.080.100.140.170.20

0.520.630.831.041.25

0.440.600.170.300.56

NOTES:1. The data listed covers pipe manufactured to specifications noted in Table 7-6.2. Data based on information compiled by American Society of Mechanical Engineers.3. “S” Suffix to schedule number denotes wall thickness which pertains only to stainless steel pipe. Stainless

steel pipe schedule numbers with dimensions and schedule numbers the same as steel pipe are not suffixed.4. Dimensions and weights shown in the tables are theoretical and are subject to standard mill tolerances.5. Pipe weights are figured on the basis of one cubic inch of steel weighing 0.2833 lb. (489.5 lb./cu. ft.).6. The outside diameter of a given size of pipe is the same regardless of the weight per foot. Variations in

weight or wall thickness affect the inside diameter only.7. Standard pipe sizes 1/8 in. to 12 in. are known by nominal inside diameter (ID). Pipe sizes 14 in. and over

are known by the outside diameter (OD).8. Sch. 40 is the same as “standard wall” up to 10-inch size. Sch. 80 is the same as “Extra Strong” up to 8-inch

size.9. Data for piping with a greater wall thickness than schedule 80 has been intentionally omitted based on its

limited application and use in the Water Supply Industry. None scheduled, or otherwise identified wallthickness are not shown.

10. Burst pressure calculations are based on Barlow’s formula; Pb = 2t (Sy)/OD 11. Collapse pressure calculations are based on Stewart’s formula;

Pc = 2008 (Sy) (t/OD), for t/OD < .023Pc = 3.467 (Sy) (t/OD) - Sy (.055), for t/OD > .023

12. Working pressure (WP) calculations are based on a safety factor (SF) of 6 and does not take into accountmill tolerances, temperature or threading. To find WP at another SF, divide burst pressure rating by desiredSF. Both Burst pressure (Pb) and Collapse pressure (Pc) are theoretical and contain no service factor.

*Does not conform to USA B36.10-1959


Sect

ion

7


Table 7-3: Light Wall Welded Steel Pipe (Gauge Pipe)

Pipe Size Wall Thk. Wall Thk. Wt./ft.(in.) (GA) (lbs./ft.) (lbs./ft.)

3 OD 141210

.083

.109

.134

2.43.34.2

Pipe Size Wall Thk. Wall Thk. Wt./ft.(in.) (GA) (lbs./ft.) (lbs./ft.)

10 3/4 OD 1210

.109

.13412.215.6

12 OD 1210

3/16”1/4”

.109

.134

.188

.250

13.617.523.731.4

12 3/4 OD 1210

.109

.13414.518.6

14 OD 1210

.109

.13415.920.4

16 OD 1210

.109

.13418.223.4

18 OD 1210

.109

.13420.526.3

20 OD 1210

.109

.13422.829.3

22 OD 1210

.109

.13425.132.2

24 OD 1210

.109

.13427.435.1

26 OD 1210

.109

.13429.738.1

28 OD 1210

.109

.13432.041.0

30 OD 1210

3/16”

.109

.134

.188

34.244.059.7

32 OD 1210

3/16”

.109

.134

.188

36.547.063.7

34 OD 1210

3/16”

.109

.134

.188

38.849.967.7

36 OD 1210

3/16”-

.109

.134

.188-

41.152.971.7

-

3 1/2 OD 141210

.083

.109

.134

2.83.95.0

4 OD 141210

.083

.109

.134

3.24.55.7

4 1/2 OD 141210

.083

.109

.134

3.65.06.4

5 OD 141210

3/16”

.083

.109

.134

.188

4.05.67.29.6

6 OD 141210

3/16”

.083

.109

.134

.188

4.86.88.611.6

6 5/8 OD 141210

.083

.109

.134

5.47.59.6

7 OD 141210

3/16”

.083

.109

.134

.188

5.77.910.113.6

8 OD 141210

3/16”

.083

.109

.134

.188

6.59.011.615.6

8 5/8 OD 1210

.109

.1349.812.5

10 OD 1210

3/16”1/4”

.109

.134

.188

.250

11.314.519.726.0


Section 7


Table 7-4: Designation of U.S. Pipe Sizes to the Metric System

Customary Proposed Customary Proposed Customary ProposedInches Millimeters Inches Millimeters Inches Millimeters

1/4 8 3 1/2 90 24 6003/8 10 4 100 30 7501/2 15 6 150 36 9003/4 20 8 200 42 1,0501 25 10 250 48 1,200

1 1/4 32 12 300 54 1,3501 1/2 40 14 350 60 1,500

2 50 16 400 72 1,8002 1/2 65 18 450 78 1,950

3 80 20 500 84 2,100

Note: It is the intention of most authorities for the United States to eventually convert all IPS measurements tothe metric system. The following metric equivalents to conventional U.S.- IPS pipe sizes have been proposed.These are in agreement with British and German standards.


Sect

ion

7


Tab

le 7

-5:

Co

mm

on

Pip

e S

pe

cif

ica

tio

n f

or

Ste

el

Tu

bu

lars

use

d i

n t

he

Wa

ter

Su

pp

ly a

nd

Oil I

nd

ust

ry

Spec

ific

atio

n a

nd

Size

Ran

gew

her

e in

dic

ated

Sco

pe

Typ

eG

rad

esTen

sile

sW

all

To

lera

nce

OD

To

lera

nce

A-5

31/

8” -

26”

Blk

& G

alv

Wel

ded

& S

MLS

Suita

ble

for

wel

din

g an

d form

ing

oper

atio

ns

CW

.N

ot in

tended

for

close

coili

ng

or

seve

reco

ld form

aing.

Pip

e re

quired

for

close

coili

ng

should

be

spec

ified

in o

rder

.

CW

- T

ype

F

ERW

- T

ype

E

SMLS

- T

ype

S

CW

- T

ype

F

ERW

& S

MLS

Gra

des

A&

B

MIN

. P.

S. I.

GRAD

EY

IELD

TEN

SILE

F25

,000

45,0

00G

R-A

30,0

0048

,000

GR-B

35,0

0060

,000

Min

. w

all sh

all not be

more

than

12.

5% u

nder

nom

. w

alls

1/2”

to 1

1/2

” + 1

/64”

- 1-

32”

2” &

ove

r-+/-

1%

of

OD

A-1

061/

8” -

26”

SMLS

for

hig

h tem

per

ature

ser

vice

.Su

itable

for

ben

din

g, f

langi

ng

and

sim

ula

r fo

rmin

g oper

atio

ns

SMLS

Only

Gra

des

A, B, C

MIN

. P.

S. I.

GRAD

EY

IELD

TEN

SILE

A30

,000

48,0

00B

35,0

0060

,000

C40

,000

70,0

00

Min

. w

all sh

all not be

more

than

12.

5% u

nder

nom

. w

all

2” to

4” +

/- 1

/32”

5” to

8” +

1/1

6” -

1/3

2”10

” to

18”

+ 3

/32”

- 1

/32”

18”

& O

ver

+ 1/

8” -

1/3

2”

A-1

201/

8” -

16”

Blk

& G

alv

Wel

ded

& S

MLS

pip

e fo

rord

inar

y use

not in

tended

for

close

coili

ng,

ben

din

g or

hig

h tem

per

ature

serv

ice

CW

ERW

SMLS

NO

NE

Spec

ifie

dM

in. w

all sh

all not be

more

than

12.

5% u

nder

nom

inal

wal

l

NO

NE S

PECIF

IED

1/2”

to 1

1/2

+ 1

/64”

- 1-

32”

2” &

ove

r-+/-

1%

of

OD

A-1

352”

- 3

0”Ele

ctric

resi

stan

ce W

elded

for

conve

ying

liquid

, ga

s or

vapor

ERW

Only

Gra

des

A&

BM

IN. P.

S. I.

GRAD

EY

IELD

TEN

SILE

A30

,000

48,0

00B

35,0

0060

,000

Min

. w

all sh

all not be

more

than

12.

5% u

nder

Nom

. w

all

For

all si

zes:

+/-

1%

of

OD

A-5

89Typ

e I

6” -

16”

Typ

e II

1” -

12”

Typ

e III

1” -

2”

Typ

e IV

3.50

0” -

8.6

25”

SMLS

& W

elded

Wat

er p

ipe

Typ

e I

Drive

Pip

e

Typ

e II W

ater

Wel

l Rea

med

and D

rifted

Typ

e III

Drive

n W

ell Pip

e

Typ

e IV

Wat

er W

ell Cas

ing

Typ

e I

SMLS

or

WELD

ED

Typ

e II

SMLS

, ERW

or

CW

Typ

e III

SMLS

, ERW

or

CW

Typ

e IV

SMLS

, ERW

or

CW

Typ

e I

A o

r B

Typ

e II A

or

CW

Typ

e III

A o

r CW

Typ

e IV

A o

r CW

MIN

. P.

S. I.

GRAD

EY

IELD

TEN

SILE

CW

25,0

0045

,000

A30

,000

48,0

00B

35,0

0060

,000

Min

. w

all sh

all not be

more

than

12.

5% u

nder

Nom

. w

all

1 1/

2” &

under

+ 1

/64”

- 1

/32”

2” &

ove

r+/-

1%

of

OD

API

5LW

elded

and S

MLS

Lin

e Pip

eCW

ERW

SMLS

CW

- G

rade

25

ERW

& S

MLS

Gra

des

A &

B

MIN

. P.

S. I.

GRAD

EY

IELD

TEN

SILE

A-2

525

,000

45,0

00A

30,0

0048

,000

B35

,000

60,0

00

2 7/

8” &

sm

aller

+ 2

0% -

12.5

%3

1/2”

OD

+18

% -

12.5

%4”

- 18

” +15

% -1

2.5%

20” &

larg

er +

17.

5% -

10%

+ 15

% -

12.5

%

19.00

& u

nder

+ .01

6” -

.031”

2 3/

8” t

o 4”

OD

= +/

- 1%

4 1/

2” &

ove

r +/-

.75%

+ .75

%API

5LX

Wel

ded

and S

MLS

Hig

h T

est Li

ne

Pip

eERW

& S

MLS

X-4

2 X-4

6X-5

2X-6

0

MIN

. P.

S. I.

GRAD

EY

IELD

TEN

SILE

X-4

242

,000

60,0

00X-4

646

,000

63,0

00X-5

252

,000

66,0

00X-6

060

,000

75,0

00

Feder

alW

WP-4

06Com

par

able

to A

-120

Com

par

able

to A

-120

Feder

alW

WP-4

06Com

par

able

to A

-120

Com

par

able

to A

-120


Section 7


Table 7-6: Specification for Wrought Steel and Stainless Steel Pipe

ANSI ASTM or APIDesignation Designation Title

B36.1 ASTM A53 Welded and Seamless Steel Pipe

B36.2 ASTM A72 Welded Wrought Iron Pipe

B36.3 ASTM A106 Seamless Carbon-Steel Pipe for High-Temperature Service

B36.20 ASTM A120 Black and Hot-Dipped Zinc-Coated (Galvanized)Welded and Seamless Steel Pipe for Ordinary Uses

B36.4 ASTM A134 Electric-Fusion (Arc)-Welded Steel Plate Pipe, Sized 16 in. and over

B36.5 ASTM A135 Electric-Resistance-Welded Steel Pipe

B36.9 ASTM A139 Electric-Fusion (Arc)-Welded Steel Pipe, Sized 4 in. and over

B36.11 ASTM A155 Electric-Fusion-Welded Steel Pipe for High-Temperature Services

B36.16 ASTM A211 Spiral-Welded Steel or Iron Pipe

B36.26 ASTM A312 Seamless and Welded Austenitic Stainless Steel Pipe

B36.40 ASTM A333 Seamless and Welded Steel Pipe for Low-Temperature Service

B36.42 ASTM A335 Seamless Ferritic Alloy Steel Pipe for High-Temperature Service

B36.47 ASTM A358 Electric-Fusion-Welded Austenitic Chromium-Nickel Alloy Steel Pipefor High-Temperature Service

B36.48 ASTM A369 Ferritic Alloy Steel Forged and Bored Pipe for High-TemperatureService

B36.43 ASTM A376 Seamless Austenitic Steel Pipe for High-Temperature Central-StationService

B36.49 ASTM A381 Metal-Arc Welded Steel Pipe for High-Pressure Transmission Service

API 5L Line Pipe

API 5LX High-Test Line Pipe

Source: American Society of Mechanical Engineers, (ANSI B36.10-59)

Table 7-7: Typical Composition of Stainless and Mild Steel Piping Material

CHEMICAL Piping Material Ladle Analysis

COMPONENT * SS 304 * SS 316 * SS 904L A53 (Mild Stl.)

CARBON (C) 0.08 0.08 .02 0.25 - 0.30MANGANESE (Mn) 2.00 2.00 2 0.05 - 1.20PHOSPHOROUS (P) 0.04 0.045 - 0.05SULFUR (S) 0.03 0.03 - 0.06 SILICON (Si) 0.75 1.00 1 -CROMIUM (Cr) 18.0 - 20.0 16.0 - 18.0 21 -NICKEL (Ni) 8.0 - 11.0 10.0 - 14.0 26 -MOLYBDENUM (Mo) - 2.0 - 3.0 4.5 -IRON (Fe) REMAINDER REMAINDER REMAINDER REMAINDER

Note: 300 Series Stainless Steel pipe are typically manufactured to ASTM A312 or A358 specifications* Austenitic Stainless Steel


Sect

ion

7


Table 7-8: ANSI 150 and 300 lb. Steel Flange Dimensions

Nom. Dia. of Flange Flange thk. Bolt Circle Dia.dia. (OD) inches. (t) inches. (BC) inches. No. of Bolts Bolt Size

(in.) 150 lb. 300 lb. 150 lb. 300 lb. 150 lb. 300 lb. 150 lb. 300 lb. 150 lb. 300 lb.

1/2 3 1/2 3 3/4 7/16 9/16 2 3/8 2 5/8 4 4 1/2 1/23/4 3 7/8 4 5/8 1/2 5/8 2 3/4 3 1/4 4 4 1/2 5/81 4 1/4 4 7/8 9/16 11/16 3 1/8 3 1/2 4 4 1/2 5/8

1 1/4 4 5/8 5 1/4 5/8 3/4 3 1/2 3 7/8 4 4 1/2 5/8

1 1/2 5 6 1/8 11/16 13/16 3 7/8 4 1/2 4 4 1/2 3/42 6 6 1/2 3/4 7/8 4 3/4 5 4 8 5/8 5/8

2 1/2 7 7 1/2 7/8 1 5 1/2 5 7/8 4 8 5/8 3/43 7 1/2 8 1/4 15/16 1 1/8 6 6 5/8 4 8 5/8 3/4

3 1/2 8 1/2 9 15/16 1 3/16 7 7 1/4 8 8 5/8 3/44 9 10 15/16 1 1/4 7 1/2 7 7/8 8 8 5/8 3/45 10 11 15/16 1 3/8 8 1/2 9 1/4 8 8 3/4 3/46 11 12 1/2 1 1 7/16 9 1/2 10 5/8 8 12 3/4 3/4

8 13 1/2 15 1 1/8 1 5/8 11 3/4 13 8 12 3/4 7/810 16 17 1/2 1 3/16 1 7/8 14 1/4 15 1/4 12 16 7/8 112 19 20 1/2 1 1/4 2 17 17 3/4 12 16 7/8 1 1/8

14 OD 21 23 1 3/8 2 1/8 18 3/4 20 1/4 12 20 1 1 1/8

16 OD 23 1/2 25 1/2 1 7/16 2 1/4 21 1/4 22 1/2 16 20 1 1 1/418 OD 25 28 1 9/16 2 3/8 22 3/4 14 3/4 16 24 1 1/8 1 1/420 OD 27 1/2 30 1/2 1 11/16 2 1/2 25 27 20 24 1 1/8 1 1/424 OD 32 36 1 7/8 2 3/4 29 1/2 32 20 24 1 1/4 1 1/2

Notes: 1. SAE Grade 5 or better fasteners are recommended for 150 - 300 lb. flange service.2. Steel flange configurations for attachment are slip-on, welding neck, socket weld or threaded. Flanges

are manufactured in a variety of mating faces, with the flat or raised face being the most common forwater supply service.

3. Ductile Iron flange dimensions for 250 psi service are the same as steel for 150 psi service.4. ANSI flanges are available rated for 150,300, 400, 600, 900, 1500 and 2500 psi service. 5. Pressure ratings:

a. 250 psi DI flanges are continuously rated at 400 psi for cool water service (<100°F) in 12” andsmaller sizes.

b. 150 and 300 psi steel flanges have a continuously rating of 275 and 720 psi respectively for coolwater service.

6. Flanged column pipe for suspended pump applications do not generally match ANSI standard inconsideration of space and strength requirements.


Section 7


Table 7-9: ANSI 150 lb. Flange Guide - Gasket and Machine Bolt Dimensions

PIPE No. Mach. Bolt Gasket Dimensions

SIZE Bolts Dimension Ring Full Face

2 4 5/8 X 2 3/4 2 3/8 X 4 1/8 2 3/8 X 6

2 1/2 4 5/8 X 3 2 7/8 X 4 7/8 2 7/8 X 7

3 4 5/8 X 3 3 1/2 X 5 3/8 3 1/2 X 7 1/2

3 1/2 8 5/8 X 3 4 X 6 3/8 4 X 8 1/2

4 8 5/8 X 3 4 1/2 X 6 7/8 4 1/2 X 6 7/8

5 8 3/4 X 3 1/4 5 9/16 X 7 3/4 5 9/16 X 10

6 8 3/4 X 3 1/4 6 5/8 X 8 3/4 6 5/8 X 110

8 8 3/4 X 3 1/2 8 5/8 X 11 8 5/8 X 13 1/2

10 12 7/8 X 3 3/4 10 3/4 X 13 3/8 10 3/4 x 16

12 12 7/8 X 4 12 3/4 X 16 1/8 12 3/4 X 19

Note: All dimension are in inches where applicable.


Sect

ion

7


Table 7-10: Friction Loss for Water in New Sch. 40 Steel Pipe @ 60°F (Frict. loss in ft. per 100 ft. - Vel. in ft. per sec.)

1/8” (0.26 ID) 1/4” (0.36 ID) 3/8” (0.49 ID) 1/2” (0.62 ID) 3/4” (0.82 ID) 1” (1.04 ID)

gpm Vel. Frict. Vel. Frict. Vel. Frict. Vel. Frict. Vel. Frict. Vel. Frict. gpm

0.10.20.30.40.50.60.70.80.91.01.21.41.51.61.82.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.510.012141516182025303540455060

0.571.131.692.262.823.393.954.525.085.656.77******************************************************************************************************

1.362.729.7016.224.233.844.857.471.687.0122******************************************************************************************************

0.310.62***

1.23***

1.85***

2.47***

3.083.704.32***

4.935.556.177.719.2510.812.313.915.4*********************************************************************

0.410.81***

3.70***

7.60***

12.7***

19.126.735.3***

45.256.469.0105148200259326396*********************************************************************

0.841.01***

1.34***

1.68******

2.52******

3.364.205.045.886.727.568.409.2410.1***

11.8***

13.4***

15.1***

16.8***************************************

1.261.74***

2.89***

4.30******

8.93******

15.022.631.842.654.968.483.5100118***158***205***258***316***************************************

1.06******

1.58******

2.112.643.173.704.224.755.285.816.346.867.397.928.458.989.5010.010.612.714.8*********************************

1.86******

2.85******

4.787.1610.013.317.121.329.830.936.542.448.755.562.770.378.386.995.9136183*********************************

0.60******

0.90******

1.20***

1.81***

2.41***

3.01***

3.61***

4.21***

4.81***

5.42***

6.027.228.429.029.6310.812.015.118.1***************

0.26******

0.73******

1.21***

2.50***

4.21***

6.32***

8.87***

11.8***

15.0***

18.8***

27.032.643.550.056.370.386.1134187***************

0.37***************

0.74***

1.11***

1.48***

1.86***

2.23***

2.60***

2.97***

3.34***

3.714.455.20***

5.946.687.429.2711.113.014.816.718.622.3

0.11***************

0.38***

0.78***

1.30***

1.93***

2.68***

3.56***

4.54***

5.65***

6.869.6212.8***

16.520.625.138.754.673.395.0119146209

0.10.20.30.40.50.60.70.80.91.01.21.41.51.61.82.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.510.012141516182025303540455060


Section 7


Table 7-10: Friction Loss for Water in New Sch. 40 to Steel Pipe @ 60°F(Frict. loss in ft. per 100 ft. - Vel. in ft. per sec.) (continued)

1 1/4” (1.38 ID) 1 1/2” (1.61 ID) 2” (2.07 ID) 2 1/2” (2.47 ID) 3” (3.07 ID) 4” (4.07)


5101214161820253035404550607080901001201401601802002202402602803003504004505005506006507007508008509009501000110012001400

1.072.152.573.003.433.864.295.376.447.528.589.6610.712.915.017.219.321.525.730.0***************************************************************************

0.521.772.483.284.205.256.349.6613.618.523.529.536.051.068.889.2112138197267***************************************************************************

0.791.581.892.212.522.843.153.944.735.526.307.107.889.4611.012.614.215.818.922.125.228.431.5******************************************************************

0.250.831.161.531.962.422.944.506.268.3810.813.516.423.231.340.551.062.288.3119158199241******************************************************************

0.480.961.151.341.531.721.91***

2.873.353.824.304.785.746.697.658.609.5611.513.415.317.219.121.022.924.926.828.7***************************************************

0.070.250.350.460.590.730.87***

1.822.423.103.824.676.598.8611.414.217.424.733.243.054.166.380.095.0111128146***************************************************

0.670.800.941.071.211.34***

2.012.352.683.023.354.024.695.366.036.708.049.3810.712.113.414.716.117.418.820.123.526.830.233.5***************************************

0.100.150.200.250.310.36***

0.751.001.281.571.942.723.634.665.827.1110.013.517.421.926.732.238.144.551.358.579.2103132160***************************************

0.43************

0.87***

1.30***

1.82***

2.172.60***

3.47***

4.345.216.086.947.818.689.5510.411.312.213.015.217.419.621.723.926.028.230.4***

34.7*********************

0.04************

0.13***

0.27***

0.55***

0.660.92***

1.57***

2.393.374.515.817.288.9010.712.614.716.919.226.333.943.052.563.875.788.6101***131*********************

0.50***

0.76***

1.01***

1.261.511.762.022.272.523.023.534.034.545.045.546.056.557.067.568.8210.111.312.613.915.116.417.618.920.221.422.723.925.227.730.235.3

0.04***

0.07***

0.12***

0.180.250.330.420.520.610.861.161.491.892.272.703.193.724.284.896.558.4710.513.015.718.621.725.328.932.837.041.446.050.961.472.097.6

5101214161820253035404550607080901001201401601802002202402602803003504004505005506006507007508008509009501000110012001400


Sect

ion

7


Table 7-10: Friction Loss for Water in New Sch. 40 to Steel Pipe @ 60°F(Frict. loss in ft. per 100 ft. - Vel. in ft. per sec.) (continued)

5” (5.05 ID) 6” (6.07 ID) 8” (7.98 ID) 10” (10.02ID) 12” (11.94 ID) 14” (13.12 (ID)


40608010012014016018020022024026028030035040045050055060070080090010001100120013001400150016001700180019002000250030003500400045005000600070008000900010000

0.640.961.281.601.922.252.572.893.213.533.854.174.494.815.616.417.228.028.819.6211.212.814.416.0***

19.2***

22.5***

25.7***

28.8***

32.1*********************************

0.040.080.140.210.290.390.480.600.730.871.031.191.371.582.112.723.414.164.945.887.9310.212.915.8***

22.5***

30.4***

39.5***

49.7***

61.0*********************************

1.111.331.551.782.002.222.442.662.893.113.333.894.445.005.556.116.667.778.889.9911.112.213.314.415.516.717.818.920.021.122.227.7******************************

0.090.120.160.200.250.300.360.410.480.540.620.851.091.361.661.972.333.134.045.086.237.498.8710.412.013.715.617.519.621.824.137.2******************************

1.151.281.411.541.671.801.922.242.572.893.213.533.854.495.135.776.417.057.708.348.989.6210.310.911.512.212.816.019.222.425.7*********************

0.070.080.100.110.130.150.170.220.280.340.420.500.590.791.011.271.551.862.202.562.963.383.834.294.815.315.918.9012.817.522.0*********************

1.221.421.631.832.032.242.442.853.253.664.074.484.885.295.706.106.516.927.327.738.1410.212.214.216.318.320.324.4************

0.060.070.090.120.140.170.200.250.330.410.490.590.700.810.941.071.211.381.521.681.862.864.065.467.078.9111.015.9************

1.431.581.722.012.292.582.873.153.443.734.014.304.594.875.165.455.737.178.6010.011.512.914.317.220.122.9******

0.060.070.080.110.140.180.210.250.290.340.390.440.500.570.640.700.781.191.682.252.923.654.476.398.6311.2******

1.902.142.372.612.853.083.323.563.804.034.274.514.745.937.128.309.4910.711.914.216.619.021.423.7

0.090.110.130.160.180.210.240.280.310.350.390.430.480.731.041.401.812.272.794.005.376.988.7910.8

40608010012014016018020022024026028030035040045050055060070080090010001100120013001400150016001700180019002000250030003500400045005000600070008000900010000


Section 7


Table 7-10: Friction Loss for Water in New Sch. 40 Steel Pipe @ 60°F(Frict. loss in ft. per. 100 ft. - Vel in ft. per sec.) (continued)

16” (15.00 ID) 18” (16.88 ID) 20” (18.81) 24” (22.62ID) 30” (29.00 ID)* 36” (35.00 ID)*


1000150020002500300035004000450050006000700080009000

10,00012,00014,00016,00018,00020,00025,00030,00035,00040,00050,000

1.822.723.634.545.456.357.268.179.0810.912.714.516.318.221.825.429.0*********************

0.070.140.250.380.540.720.921.151.412.012.693.494.385.387.6910.413.5*********************

2.873.594.305.025.746.457.178.6110.011.512.914.317.220.122.925.828.7***************

0.140.210.300.400.510.640.781.111.491.932.422.974.215.697.419.3311.5***************

2.312.893.464.044.625.195.776.928.089.2310.411.513.816.218.520.823.128.934.6*********

0.080.120.170.230.300.370.460.650.861.111.391.702.443.294.265.356.5610.214.6*********

2.392.793.193.593.994.795.596.387.187.989.5811.212.814.416.020.023.927.9******

0.070.090.120.150.180.260.340.440.550.670.961.291.672.102.584.045.687.73******

1.94***

2.432.913.403.894.374.865.836.807.778.749.7112.114.617.019.4***

0.03***

0.050.080.100.130.160.200.280.370.480.600.731.131.612.172.83***

1.581.892.212.522.843.153.784.415.045.676.307.889.4611.012.615.8

0.020.030.040.040.060.070.090.130.160.200.250.380.540.720.941.45

1000150020002500300035004000450050006000700080009000

10,00012,00014,00016,00018,00020,00025,00030,00035,00040,00050,000

Note:

1. Table based on Darcy-Weisback formula; with no allowance for age, differences in diameter, or any otherabnormal condition of interior surface. Any Factor of Safety must be estimated from the local conditions andthe requirements of each particular installation. For general purposes, 15% is a reasonable Factor of Safety.

2. The friction loss data is based on seamless Sch. 40 steel pipe. Cast iron (CI) pipe has a slightly larger ID thansteel pipe in the 3” to 12” dia. range, which generally makes no practical difference with respect to watersupply pumping problems.

3. Ductile Iron (DI) has a larger ID than both Sch. 40 steel and CI pipes for the same nominal diameter. FrictionLosses in DI pipe can be approximated by multiplying the tabulated value by .75 in the 4” to 12” size rangeand .60 for 14” and larger sizes.

4. Velocity head values are not included in the table, as they are normally not considered as a component ofTotal Head (TH) calculations to solve water supply pumping problem. Velocity and Velocity head can becalculated using the following formulas:

Vel. (fps) = gpm (.410)/(ID)2 = gpm (.321)/Area (in.2); where: Area (in2) = π (ID)2/4Vel. Head (ft.) = (Vel.)2 /2g = (Vel.)2/64.4

5. Velocity within column (vertical drop/riser pipe) should be kept within the range of 4 - 15 fps (5.0 fps is optimum).Velocity within horizontal distribution piping should be kept within the range of 1 - 6 fps (3.0 fps is optimum).

6. Tabulated friction loss values are calculated based on water at 60°F and a kinematic viscosity = 0.00001217 ft/sec. (31.2 SSU). Correct tabulated values for fluid temperatures other than 60°F as following:

Temp (°F) 32 40 50 60 80 100 150 200 212Correction factor 1.20 1.10 1.00 1.00 1.00 .95 .90 .85 .80

* The ID value specified for 30” and 36” sizes are for Sch. 20 pipe. Sch. 40 pipe is not available in diametersgreater than 24”


Sect

ion

7


Table 7-11: Friction Loss for Water in New Type L Copper Tubing and Sch. 40 PVC Pipe(Frict. loss in ft. per 100 ft. - Vel. in ft. per sec.)

Tubing Pipe

1/2” .545” ID .622” ID

gpm Vel. Frict. Vel. Frict.

Tubing Pipe

3/4” .785” ID .824” ID


0.51.01.5

0.691.382.06

0.752.454.93

0.521.041.57

0.401.282.58

123

0.661.331.99

0.441.442.91

0.601.211.81

0.351.162.34

2.02.53.0

2.753.444.12

8.1111.9816.48

2.092.613.13

4.246.258.59

456

2.653.313.98

4.817.119.80

2.423.023.62

3.865.717.86

3.54.04.5

4.815.506.19

21.6127.3333.65

3.664.184.70

11.2514.2217.50

789

4.645.305.96

12.8616.2820.06

4.234.835.44

10.3213.0716.10

5.06.07.0

6.878.259.62

40.5256.0273.69

5.226.267.31

21.0729.0938.23

101112

6.927.297.95

24.1928.6633.47

6.046.647.25

19.4122.9926.84

8.09.010.0

11.012.413.8

93.50115.4139.4

8.359.4010.4

48.4759.7972.16

131415

8.619.279.94

38.6144.0749.86

7.858.459.05

30.9635.3339.97

12.014.016.0

12.614.7

115.6157.4

161718

10.6011.2511.92

55.9762.3969.13

9.6510.2510.85

44.8650.0055.40

Tubing Pipe

1” 1.03” ID 1.05” ID


Tubing Pipe

1 1/4” 1.27” ID 1.38” ID


234

0.781.171.56

0.410.821.35

0.721.081.45

0.350.701.14

567

1.281.531.79

0.741.011.32

1.091.311.53

0.510.700.91

567

1.952.342.72

2.002.753.60

1.812.172.53

1.692.323.04

8910

2.042.302.55

1.672.062.48

1.751.962.18

1.151.421.71

8910

3.113.503.89

4.565.616.76

2.893.253.61

3.854.745.71

121520

3.063.835.10

3.425.078.46

2.623.274.36

2.353.495.81

121416

4.675.456.22

9.3312.2715.56

4.345.055.78

7.8810.3613.13

253035

6.387.658.94

12.5917.4423.00

5.466.557.65

8.6511.9815.79

182025

7.007.789.74

19.2023.1834.56

6.507.229.03

16.2019.5529.15

404550

10.211.512.8

29.2436.1543.71

8.749.8310.9

20.0624.8029.98

303540

11.6813.6115.55

47.9663.3180.58

10.8412.6514.45

40.4353.3767.90

607080

15.317.920.4

60.7880.38102.5

13.115.317.5

41.6655.0770.16

7-17Section 7A Technical Appendices


Section 7

Table 7-11: Friction Loss for Water in New Type L Copper Tubing and Sch. 40 PVC Pipe(Frict. loss in ft. per 100 ft. - Vel. in ft. per sec.) (continued)

Tubing Pipe

1 1/2” 1.51” ID 1.61” ID


Tubing Pipe

2” 1.98” ID 2.07” ID


8910

1.441.621.80

0.730.901.08

1.271.431.59

0.550.670.81

161820

1.661.872.07

0.660.820.98

1.531.721.92

0.550.680.82

121520

2.162.703.60

1.492.213.68

1.912.393.19

1.121.652.75

253035

2.593.113.62

1.462.012.65

2.392.873.35

1.221.682.21

253035

4.515.416.31

5.487.589.99

3.984.785.58

4.095.657.45

404550

4.144.665.17

3.364.155.01

3.834.304.80

2.803.464.17

404550

7.218.119.01

12.6815.6718.94

6.377.167.96

9.4511.6814.11

607080

6.217.258.28

6.959.1611.65

5.756.707.65

5.797.639.70

607080

10.812.614.4

26.3034.7444.24

9.5611.212.8

19.5925.8732.93

90100110

9.3110.411.4

14.4117.4320.71

8.619.5710.5

12.0014.5117.24

90100110

16.218.019.8

54.7866.3478.90

14.415.917.5

40.7679.3458.67

120130140

12.413.414.5

24.2528.0432.07

11.512.513.4

20.1823.3326.69

Tubing Pipe

2 1/2” 2.46” ID 2.47” ID


Tubing Pipe

3” 2.95” ID 3.07” ID


202530

1.341.682.02

0.350.520.72

1.311.631.96

0.330.490.67

203040

0.941.411.88

0.150.310.51

0.871.301.74

0.130.250.42

354045

2.352.693.02

0.941.191.47

2.292.612.94

0.881.121.38

506070

2.352.823.29

0.761.051.38

2.172.613.04

0.630.871.15

506070

3.364.034.70

1.772.463.24

3.263.924.57

1.662.303.03

8090100

3.764.234.70

1.752.162.61

3.483.914.35

1.451.802.17

8090100

5.376.046.71

4.125.086.15

5.225.886.53

3.854.755.74

110120130

5.175.646.11

3.103.634.19

4.795.215.65

2.573.013.47

110120130

7.388.058.73

7.308.549.87

7.197.848.49

6.827.929.22

140150160

6.587.057.52

4.795.426.09

6.096.526.95

3.974.505.05

140150160

9.4010.110.8

11.2812.7814.36

9.149.7910.45

10.5411.9413.42

170180190

7.998.468.93

6.807.548.32

7.397.828.25

5.646.256.89

170180190

11.412.112.8

16.0317.7919.62

11.111.812.4

14.9816.6118.33

200220240

9.4010.311.3

9.1310.8512.70

8.709.5610.40

7.568.9910.52

200220240

13.414.816.1

21.5425.6130.01

13.114.415.7

20.1223.9328.03

260280300

12.213.214.1

14.6916.8119.06

11.312.213.0

12.1713.9315.79


Sect

ion

7


Table 7-11: Friction Loss for Water in New Type L Copper Tubing and Sch. 40 PVC Pipe(Frict. loss in ft. per 100 ft. - Vel. in ft. per sec.) (continued)

Tubing Pipe

3 1/2” 3.43” ID 3.55” ID


Tubing Pipe

4” 3.91” ID 4.63” ID


607080

2.092.442.78

0.510.670.85

2.002.332.66

0.460.600.77

100110120

2.682.943.21

0.680.800.94

2.552.813.06

0.600.710.83

90100110

3.133.483.82

1.051.271.50

3.003.333.67

0.951.141.35

130140150

3.483.744.01

1.081.231.40

3.313.573.83

0.961.101.25

120130140

4.184.524.87

1.762.032.32

4.004.334.66

1.581.832.09

160170180

4.284.554.81

1.571.751.94

4.084.334.58

1.391.561.73

150160170

5.215.565.91

2.622.953.29

5.005.335.66

2.362.662.96

190200220

5.085.355.89

2.142.352.79

4.845.105.61

1.912.092.48

180190200

6.266.606.95

3.644.024.41

6.006.336.66

3.283.623.97

240260280

6.426.957.49

3.263.774.31

6.126.637.14

2.903.363.84

220240260

7.658.359.05

5.246.137.09

7.338.008.66

4.725.526.39

300350400

8.029.3610.7

4.886.468.23

7.658.9210.2

4.355.757.33

280300350

9.7410.412.2

8.119.1912.16

9.3310.011.7

7.308.2810.95

450500550

12.013.414.7

10.2012.3614.71

11.512.814.1

9.0811.0013.09

400450500

13.915.617.4

15.5119.2323.32

13.315.016.7

13.9717.3220.99

600650700

16.017.418.7

17.2419.9622.86

15.316.617.9

15.3517.7720.35

Note: 1. The friction losses listed under the pipe heading is approximately valid for Regular Weight Copper andBrass Pipe, in addition to Sch. 40 PVC Pipe

2. Table based on Darcy - Weisback formula3. No allowance has been made for age, difference in diameter, or any abnormal condition of interior

surface. Any factor of safety must be estimated from the local conditions and the requirements of eachparticular installation. It is recommended that for most commercial design purposes a safety factor of15 to 20% be added to the values in the tables.


Section 7


Table 7-12: Friction Loss for Water in New Class 200 ~ SDR 21 ~ IPS PVC Pressure Pipe (Frict. loss in ft. per 100 ft.)

gpm 4” (4.07 ID) 5” (5.03 ID) 6” (5.99 ID) 8” (7.81 ID) 10” (9.73 ID) 12” (11.58 ID) gpm

1501601701801902002202402602803003203403603804004204404604805005506006507007508008509009501000105011001150120012501300

135014001450150016001700180019002000

1.351.361.411.571.731.902.282.673.103.564.044.565.105.676.266.98

.81

.951.101.261.431.621.822.022.222.452.692.923.183.443.70

.34

.40

.46

.54

.61

.69

.77

.86

.951.041.141.861.351.461.581.892.222.582.963.363.784.244.715.216.55

.09

.10

.12

.14

.17

.19

.21

.24

.26

.28

.31

.34

.37

.41

.48

.52

.61

.71

.81

.931.041.171.301.441.581.731.882.052.212.392.57

2.763.23.163.35

.10

.10

.11

.12

.14

.15

.18

.21

.24

.28

.32

.36

.40

.44

.49

.54

.59

.65

.70

.76

.82

.88

.951.011.081.151.301.451.621.791.97

.077

.083

.096

.110

.125

.141

.158

.175

.194

.213

.233

.254

.276

.298

.322

.346

.371

.397

.423

.451

.508

.568

.632

.698

.767

.840

1501601701801902002202402602803003203403603804004204404604805005506006507007508008509009501000105011001150120012501300

135014001450150016001700180019002000

Notes: 1. Table based on Hazen-Williams equation - C = 1502. Losses below bold line indicates velocities in excess of 5 fps, Velocities which exceed 5 fps are not

recommended.3. Friction losses listed above can be used for approximating friction loss in C900 PVC pipe of the same

nominal diameter and similar pressure rating by multiplying the tabulated figures by 1.10. Use frictionloss tables specific to C900 pipe for greater accuracy.

Conversion Factors

ConversionSDR No Class Factor

21 200 1.0026 160 .91

32.5 125 .8441 100 .78551 80 .7564 63 .71

To find friction head loss in IPSPVC pipe having a standarddimension ratio other than 21,the values in the table shouldbe multiplied by the appropriateconversion factor shown below:


Sect

ion

7


Table 7-13: Friction Loss for Water in Concrete Irrigation Pipe(Frict. loss in ft. per 100 ft.)

Flow Nominal Pipe Diameter (in.) Flow

cfs gpm 6 8 10 12 14 16 18 20 24 30 36 gpm

0.1.2.3.4.5

4590135180225

.03

.11

.26

.46

.72

.01

.02

.06

.10

.16

4590135180225

.6

.7

.8

.91.0

270315360405449

1.041.401.842.342.88

.23

.32

.41

.52

.64

.07

.10

.13

.16

.20

.03

.04

.05

.06

.08

.02

.03

.04

270315360405449

1.21.41.61.82.0

539628718808898

4.205.607.409.3011.50

.921.251.632.072.54

.28

.38

.51

.65

.80

.11

.15

.20

.24

.30

.05

.07

.08

.11

.14

.02

.03

.04

.05

.07.03.04 .02

539628718808898

2.22.42.62.83.0

9871,0771,1671,2571,346

14.0016.50

3.083.654.305.005.73

.951.141.331.551.78

.37

.44

.51

.59.68

.16

.19

.23

.26

.30

.08

.10

.11

.13

.15

.04

.05

.06

.07

.08

.03

.03

.04

.04

.05 .02

9871,0771,1671,2571,346

3.23.43.63.83.0

1,4361,5261,6161,7061,795

6.537.358.259.22

2.022.282.562.853.15

.77

.88

.981.081.22

.34

.39

.44

.49

.54

.17

.19

.22

.24

.27

.09

.10

.12

.13

.15

.05

.06

.07

.08

.09

.02

.02

.03

.03

.03

1,4361,5261,6161,7061,795

4.55.05.56.06.5

2,0202,2442,4692,6932,917

3.974.915.967.078.27

1.531.882.282.713.18

.68

.841.021.211.42

.34

.42

.50

.60

.71

.19

.23

.27

.32

.38

.11

.13

.16

.19

.22

.04

.05

.06

.07

.08

2,0202,2442,4692,6932,917

7.07.58.08.59.0

3,1423,3663,5913,8154,039

3.694.244.825.446.10

1.651.892.152.432.72

.82

.941.071.211.35

.44

.51

.58

.65

.73

.25

.29

.33

.37

.42

.10

.11

.13

.14

.15

.03

.04

.04

.05

.05

3,1423,3663,5913,8154,039

9.510.011.012.013.0

4,2644,4884,9375,3865,835

6.807.53

3.033.364.074.845.68

1.511.672.022.402.82

.82

.901.081.291.52

.47

.52

.63

.74

.88

.18

.20

.24

.29

.34

.06

.06

.07

.09

.10

.02

.02

.03

.03

.04

4,2644,4884,9375,3865,835

14.015.016.017.018.0

6,2846,7327,1817,6308,079

6.59 3.273.754.274.825.40

1.772.032.302.602.93

1.021.171.321.491.68

.39

.45

.51

.58

.65

.12

.14

.16

.18

.20

.05

.05

.06

.07

.08

6,2846,7327,1817,6308,079

20.022.024.026.028.0

8,9779,87410,77211,66912,567

6.678.07

3.594.335.196.087.01

2.072.512.883.494.04

.79

.961.141.341.56

.25

.30

.36

.41

.48

.09

.11

.14

.16

.19

8,9779,87410,77211,66912,567

30.032.034.036.038.0

13,46514,36315,26016,15817,056

4.625.335.996.71

1.792.042.292.572.86

.56

.63

.71

.80

.89

.21

.24

.27

.31

.34

13,46514,36315,26016,15817,056

Notes: 1. cfs = cu. ft. per sec., gpm = gal. per min. / gpm = gal. per min. 2. Friction loss based on full pipe. 3. Flow in “Miner’s Inch” miners inch = 9 gpm. 4. Table based on Hazen - Williams equation - C = 100


Section 7


Table 7-14: Friction Losses Through Pipe Valves and Fittings(Straight Pipe in Feet - Equivalent Length)

1/8”1/4”3/8”

.14

.21

.27

.851.251.80

5.07.09.0

192636

91216

568

2.03.04.0

.46

.60

.75

.741.01.4

.65

.861.15

.50

.70

.90

SIZE OFPIPE

(inches)WIDEOPEN

GATE VALVE1/4

CLOSED1/2

CLOSED3/4

CLOSED

GLOBEVALVE-WIDEOPEN

ANGLEVALVE-WIDEOPEN

CHECKVALVE-WIDEOPEN

ORDINARYENTRANCE

TO PIPELINES

STD.90°

ELBOW

MEDIUMSWEEP

90°ELBOW

LONGSWEEP

90°ELBOW

1/2”3/4”1”

.33

.46

.61

2.102.93.4

12.014.018.0

445970

182329

91215

5.06.07.0

.901.41.6

1.62.32.7

1.502.02.5

1.101.52.0

1 1/4”1 1/2”

2”

.79

.931.21

4.85.67.0

24.028.036.0

96116146

384658

202329

9.011.015.0

2.53.03.5

3.64.55.4

3.54.05.0

2.52.93.6

2 1/2”3”4”

1.391.692.40

8.410.014.0

41.052.070.0

172213285

6986116

354357

17.021.027.0

4.05.06.5

6.58.512.0

6.07.09.5

4.45.57.2

6”8”10”

3.404.405.70

20.026.533.5

105136172

425555703

175225285

86115141

39.53.65.

9.514.16.

17.22.27.

15.19.23.

11.215.318.2

12”14”16”

6.808.209.10

40.648.553.0

196233274

8159781110

336395435

166195220

78.92.106.

18.21.26.

33.37.43.

27.31.36.

20.223.327.5

1/8”1/4”3/8”

.40

.50

.65

1.62.33.0

2.03.04.0

.50

.70

.90

1.62.33.0

.40

.50

.65

.30

.40

.50

.16

.22

.29

.741.01.4

.46

.62

.83

.16

.22

.29

SIZE OFPIPE

(inches)45°

ELBOW

SQUARE90°

ELBOW

CLOSEDRETURNBENDS

STD.TEE

STD.TEE

dD

1/4

dD

1/2

dD

3/4

dD

1/4

dD

1/2

dD

3/4

1/2”3/4”1”

.801.01.5

4.05.06.0

5.06.07.0

1.101.52.0

4.05.06.0

.801.01.5

.60

.801.0

.36

.48

.62

1.62.32.7

1.21.41.6

.36

.48

.62

1 1/4”1 1/2”

2”

1.72.02.5

8.09.513.0

9.011.014.0

2.52.93.6

8.09.513.0

1.72.02.5

1.41.62.0

.83

.971.30

3.64.55.4

2.32.73.5

.83

.971.30

2 1/2”3”4”

3.04.05.0

15.018.023.0

16.019.025.0

4.45.57.2

15.018.023.0

3.04.05.0

2.52.94.0

1.501.802.40

6.58.012.0

4.04.86.4

1.501.802.40

6”8”10”

8.011.014.0

34.044.057.0

40.050.060.0

11.215.318.2

34.044.057.0

8.011.014.0

5.97.610.2

3.604.505.70

17.022.027.0

10.514.216.5

3.604.506.80

12”14”16”

16.018.020.0

66.079.088.0

72.084.099.0

20.223.327.5

66.079.088.0

16.018.020.0

12.314.315.4

6.708.209.30

33.037.043.0

18.422.325.5

7.509.0010.20

ABRUPT CONTRACTION ABRUPT ENLARGEMENT

Use the smaller diameter in the column for pipe size.

d=

Smaller diameter

D Larger diameter

Note: 1. 1/8” to 12” nominal sizes are based on standard steel pipe, 14” to 24” sizes are ID pipe.2. Friction losses are based on screwed connection from 1/8” to 4” sizes and flanged connections from 6” to 24”


Sect

ion

7


Figure 7-1: Typical Check Valve Friction Loss Chart

Figure 7-2: Typical Surface Plate / 90° Discharge Elbow Friction Loss Chart

SURFACE PLATE / 90° DISCHARGE FRICTION LOSS CHART


Section 7


Figure 7-3: Steel Pipe Friction Loss & Velocity Chart

Note: Above chart indicates average values for standard weight steel pipe. Hazen - Williams roughness constant(C) = 140.

Table 7-15: Equivalent Pipe Capacity Comparison

Smaller Pipe Size(Number of smaller pipes required to provide carrying capacity equal to a larger pipe)

3/4” 1” 2” 3” 4” 6” 8” 10”

2”3”4”6”8”10”12”14”16”18”20”

133984247530957

61839115247447724

1,090

126183971115174247338447

1261324395984115153

126111827395371

12369131824

11246811

112346

NOTE: Comparing the ratio of the square of diameters will provide the capacity equivalent relationship (ie. howmany 12” lines will be required to equal the capacity of a 16” line? - (16 ) / (12 ) = 1.77 or 2 - 12” lines

MainSize


Sect

ion

7


Table 7-16: Estimating Flow from Horizontal or Inclined Pipes

D Pipe Size (in.) Distance X, When Y= 12”

Nom. Act. (ID) 12 14 16 18 20 22 24 26 28 30 32

22 1/2

345681012

2.0072.4693.0684.0265.0476.0657.98110.0212.00

4260931592503623279801415

497010818629242273211451650

56801232123344828371310189

639013923937654294214752125

70100154266417602104716352360

77110169292459662115018002595

84120185318501722125519652830

91130200345543782136021303065

98140216372585842146522903300

105150231398627902157024553540

112160246425668962167526203775

D Pipe Size (in.) Distance X, When Y= 4”

Nom. Act. (ID) 4 6 8 10 12 14 16 18 20

11 1/41 1/2

22 1/2

34568

1.0491.3801.6102.0672.4693.0684.0265.0476.0057.984

5.79.813.322.031.048.083.0*********

8.514.720.033.047.073.0125195285***

11.319.626.544.062.097.0166260380665

14.224.533.255.578.0122208326476830

17.029.040.066.094.01462503905701000

20.034.046.577.01091702924566701160

22.739.053.088.01251963345207601330

60.099.01442203755908601500

1562444156509501660

Notes: 1. X = Distance; in inches, the stream travels parallel to the pipe for a 12-inch vertical drop2. D = Pipe inside diameter (in.)3. Pipe sizes based on standard weight (sch.40) steel

Flow: gpm = 0.818 X D


Section 7


Table 7-17: Estimating Flow from Partially Filled Pipes

Nom. Dia. K Nom. Dia. K Nom. Dia. K(D) (D) (D)

F/D % P F/D % P F/D % P

2 1/42 1/42 1/22 3/4

3.34.15.16.2

66 1/46 1/26 3/4

29.431.934.537.2

1010 1/410 1/210 3/4

81.785.990.194.4

33 1/43 1/23 3/4

7.38.610.011.5

77 1/47 1/27 3/4

40.042.945.949.0

1111 1/411 1/211 3/4

98.9103108113

44 1/44 1/243/4

13.114.716.518.4

88 1/48 1/28 3/4

52.355.659.062.5

1212 1/2

1313 1/2

118128138149

55 1/45 1/25 3/4

20.422.524.727.0

99 1/49 1/29 3/4

66.269.973.777.7

1414 1/2

1516

160172184209

5101520253035

.981

.948

.905

.858

.805

.747

.688

40455055605670

.627

.564

.500

.436

.375

.312

.253

7580859095100

.195

.142

.095

.052

.019

.000

Flow: gpm = X x K x P

Note: Calculate ratio F/D in %. Measure distance X in (inches) parallel to pipe for 12-inch vertical drop.(D) Nominal pipe dia. in inches, (F) Distance to water exiting end of pipe in inches.


Sect

ion

7


Table 7-18: Estimating Flow from Vertical Pipe or Casing

Nominal Diameter (D) - Standard Pipe - Inches

2 3 4 5 6 7 8 10

Flow Rate (gpm)

33 1/2

3538

7785

135149

217328

311341

425465

569626

9501055

44 1/2

4144

9298

161172

252270

369396

503540

687733

11151200

55 1/2

4749

104109

182192

286301

420444

575606

779825

12801350

66 1/2

5254

115121

202211

316331

469490

638667

872913

14151475

78910

57616569

126135144153

219236251265

345370396418

509548585321

700751802850

949102510951155

1530164017401840

1214161820

76838995101

169184197209221

294319342364386

463502540575607

685740796845890

9331020109011601225

12751380148015601645

20102170232024602600

25303540

113124135145

249273298318

433476516551

680746810865

998109511751270

1375150516301745

1840201021602320

2900318034203680

Flow: gpm = 5.68 x C x D2 x H

H(in.)

Note: 1. Pipe used for basis of calculation is standard weight (sch. 40) steel2. C = Constant Varying 0.87 to 0.97 for 2 to 6 inch diameter pipe and values of H to 24 inches

Table 7-19: Unit Conversion Tables


Section 7

Section 7A Technical Appendices

Acceleration gravity 9.80665 meter/second2

Acceleration gravity 32.2 feet/second2

Acceleration gravity 9.80665 meter/second2

Acceleration gravity 32.2 feet/second2

acre 4,046.856 meter2

acre 0.40469 hectareacre 43,560.0 foot2

acre 4,840.0 yard2

acre 0.00156 mile2 (statute)acre 0.00404686 kilometer2

acre 160 rods2

acre feet 1,233.489 meter2

acre feet 325,851.0 gallon (US)acre feet 1,233.489 meter3

acre feet 325,851.0 gallonacre-feet 43560 feet3

acre-feet 102.7901531 meter3

acre-feet 134.44 yards3

ampere 1 coulombs/secondampere 0.0000103638 faradays/secondampere 2997930000.0 statamperesampere 1000 milliamperesampere/meter 3600 coulombsangstrom 0.0001 micronsangstrom 0.1 millimicrons atmosphere 101.325 kilopascalatmosphere 1.0332 kg/cm2

atmosphere 0.10133 megapascalatmosphere 14.7 pound force/inch2

atmosphere 101325.0 newtons/meter2

atmosphere 760 torrsatmosphere 1.01325 barsatmosphere 33.8995 feet of H2O @ 40°Fatmosphere 1033.29 cm of H2O @ 4°Catmosphere 76 cm of Hg @ 0°Catmosphere 29.530 inches of Hg @ 32°Fatmosphere 760 mm of Hg @ 0°Cbars .98692 atmospherebars .1 kilopascalbars 14.50377 pound force/inch2

bars 1019.72 grams force/cm2

bars 75.0062 cm of Hg @ 0°Cbars 29.530 feet of H2O @ 40°Fbars 76 inches of Hg @ 0°Cbars 14.5038 psibarrels of oil(US) 42.0 gallons (US)barrels of oil(US) 5.61458 feet3

barrels of oil(US) 163.6592 litersboard feet 144 inch3

board feet 0.08333 foot3

board feet 2359.74 cm3

british thermal unit (BTU) 777.649 foot pound-force british thermal unit (BTU) 1,055.056 joulebritish thermal unit (BTU) 25020.1 foot poundalsbritish thermal unit (BTU) 251.996 calorie,gbritish thermal unit (BTU) 0.2520 kg-caloriebritish thermal unit (BTU) 0.000292875 kw-hoursbritish thermal unit (BTU) 0.00001 thermsbritish thermal unit (BTU) 0.000393 hp-hoursbritish thermal unit (BTU) 1054.35 watt-secondsbritish thermal unit (BTU) 10.544 x 103 ergsbritish thermal unit (BTU) 0.999331 BTU (IST)

BTU/min 0.01758 kilowattsBTU/min 0.02358 horsepowerbyte 8.000001 bitscalorie, g 0.00397 british thermal unitcalorie, g 0.00116 watt-hourcalorie, g 4184.00 x 103 ergscalorie, g 3.08596 foot pound-forcecalorie, g 4.184 joulescalorie, g 0.000001162 kilowatt-hourcalorie, g 42664.9 gram-force cmcalorie, g/hr 0.00397 btu/hrcalorie, g/hr 0.0697 wattscandle/cm2 12.566 candle/inch2

candle/cm2 10000.0 candle/meter2

candle/inch2 144.0 candle/foot2

candle power 12.566 lumenscarats 3.0865 grainscarats 200.0 milligramscelsius 1.8 C°+ 32 fahrenheitcelsius 273.16 + C° kelvincentimeter 0.39370 inchcentimeter 0.03281 footcentimeter 0.01 metercentimeter 10 millimetercm grams -force 0.0000723 foot pound-forcecm of Hg 0.1934 pound/inch2

cm/sec 0.0328 feet/seccm/sec 1.9685 feet/mincm/sec 0.0006 km/mincm/sec 0.0194 knotscm/sec 0.000373 miles/hourcm/sec/sec 0.0328 feet/sec/seccm/sec/sec 0.01 meters/sec/secchains 66.0 feetchains 20.117 metercircles 360 degreescircles 400 gradescircles 6.2832 radianscircles 12.0 signscircular inches 0.7854 inch2

centimeter2 0.15500 inch2

centimeter2 0.00108 foot2

centimeter2 127.324 circular mmcentimeter2 100.0 mm2

centimeter2 0.0001 meter2

centimeter2 155000.0 mils3

centimeter3 0.06102 inch3

centimeter3 0.00042 board feetcentimeter3 0.000035315 feet3

centimeter3 0.000001 meters3

centimeter3 0.27051 dramscentimeter3 0.06102 gallons (US)centimeter3 0.001 litercentimeter3 0.03381 ouncescentimeter3 0.00211 pintscentimeter3 0.00106 quartscentipose 0.001 pascal-secondcentistokes 0.000001 meter2/secondcoulombs 1.0 amp-hours coulombs 0.000010364 faradays coulombs 2997900000 statcoulombsdays 24.0 hours

UNIT x FACTOR = UNIT UNIT x FACTOR = UNIT

7-27

Table 7-19: Unit Conversion Tables (continued)


Sect

ion

7


days 1440. minutesdays 0.00273 yearsdays 86400 secondsdecimeter 10. centimetersdecimeter 3.937 inchdecimeter 0.32808 feetdecimeter3 61.02 inch3

degrees 60.0 minutesdegrees 3600.0 secondsdegrees 0.01111 quadrantsdegrees 0.01745 radiansdegrees 1.111 gradesdynes 0.00001 newtonsdynes/cm2 0.000001 barselectron volts 1.6021 x 10-12 ergsergs 9.4845 x 10-11 british thermal unitergs 1.0 x 10-7 joulesergs 7.376 x 10-8 foot pound-forceergs 2.3885 x 10-8 grams-calorieergs 0.278 x 10-10 watt-hoursergs 1.0 dynes-cmergs/sec 1.341 x 10-10 horsepowerfahrenheit (F°-32)/1.8 celsiusfahrenheit 0.55556 celsiusfahrenheit 459.72 + F° rankinfarads 100000 statamperes farads 1.00049 statfaradsfarads 100000 microfaradsfathoms 6.0 feetfathoms 1.828 metersfathoms 2 yardsfeet of H2O 2.98898 kilopascalfeet of H2O 0.4336 pound force/inch2

feet/second 0.508 cm/secondfeet/second 0.00508 meter/secondfeet2/second 0.000001 meter2/secondfoot 304.80 millimetersfoot 30.480 centimeterfoot 0.30480 meterfoot 0.015151 chains foot 0.000189 milesfoot 0..166667 fathomsfoot - poundals 3.9968 x 10-5 british thermal unitfoot - poundals 0.010072 cal, gramfoot - poundals 0.03108 foot pound-forcefoot - poundals 0.042133 joulefoot - pound force 1.35582 joulefoot - pound force 0.00128 british thermal unitfoot/hour (linear) 0.508 Cm/minutefoot/min .00508 meter/secfoot/sec .3048 meter/secfoot pound force 1.35582 newton meterfoot2 92,903.04 millimeter2

foot2 929.0304 centimeter2

foot2 0.09290 meter2

foot2 0.11111 yard2

foot2 0.00002 acrefoot2 3.5873 x 10-8 mile2

foot3 0.00781 cords of woodfoot3 12.0 board feetfoot3 1728.0 inches3

foot3 28316.8 centimeter3

foot3 0.02832 meter3

foot3 28.32 liter (liq.)foot3 59.842 pint (liq.)foot3 29.922 quart (liq.)foot3 7.48052 gallon (liq.)foot3 0.03704 yardfoot3/hour .0283168 meter3/hourfoot3/hour 0.0167 feet3/minutefoot3/hour 7.4805 gallons/hourfoot3/minute 0.283168 meter3/minutefoot3/minute 471.95 centimeter3/secondfoot3/second 448.8306 gallon/minutefoot3/second 0.02832 meter3/secondfoot3/second 28.31658 liter/secondfoot3/second 120.0 foot3/hourfoot3/pound 120.0 centimeter3/gramfoot3 H2O 28.31413 Kilogramfoot3 H2O 62.42197 poundfoot3 H2O 28.31413 Kilogramfoot3 H2O 62.42197 poundfurlongs 660.0 feetfurlongs 20116.8 centimetersfurlongs 201.17 metersfurlongs 7920 inchesfurlongs 220.0 yards gallon (US liq.) 8.0 pintgallon (US liq.) 4.0 quartgallon (US liq.) 3.0689 x 10-6 acre feetgallon (US liq.) 0.00379 meter3

gallon (US liq.) 3.785 litergallon (US liq.) 0.13368 foot3

gallon (US liq.) 8.33 poundsgallon H2O 3.78625 kilogramgallon H2O 3.78625 kilogramgallon H2O 8.34725 poundgallon/minute 0.00006 meter3/secondgallon/minute 0.06309 liter/secondgallon/minute 0.00144 million gallons/daygallon/minute (gpm) 0.00223 foot3/second (cfm)gallons/inch/mile/day 0.03259 liter/mm/km/daygallons/inch/mile/day 0.03259 liter/mm/km/daygausses 10000.0 gamma gausses 6.4516 lines/inch2

gausses 6.452 x 10-8 webers/inch2

gram/centimeter3 1,00.00 kilogram/meter3

grades 0.0025 circlesgrades 0.0025 circumfrenceesgrades 0.9 degreesgrades 54 minutesgrades 0.0025 revolutionsgrades 3240 secondsgrains 0.32399 caratsgrains 0.01667 drams (troy)grains 0.03657 drams (avdp)grains 64.7989 milligramsgrains 0.00017 pounds (troy)grains 0.00014 pounds (avdp)grams 5.0 caratsgrams 0.2572 drams (troy)grams 0.5644 drams (avdp)grams 15.432 grainsgrams 0.001 kilograms




Section 7


grams 1000.0 milligramsgrams 0.03215 ounce (troy)grams 0.03527 ounce (avdp)grams 0.00220 poundgrams force/cm2 98.0665 pascalgrams force/cm2 0.00034 pound force/inch2

hectare 10,000.00 meter2

hectare 2.47105 acrehenries 1000.0 millihenrieshenries 1.113 x 10-12 stathenhenrieshorsepower (mech) 2542.47 btu/hrhorsepower (mech) 0.746 kilowattshorsepower (mech) 64160.0 calories, gram/hrhorsepower (mech) 7.457 x 109 ergs/secondhorsepower (mech) 1980000.0 foot pound-force/hourhorsepower (mech) 0.076 horsepower (boiler)horsepower (mech) 0.9996 horsepower (electric)horsepower (mech) 1.0139 horsepower (metric)horsepower (mech) 745.7 joules/sechorsepower (mech) 0.212 tons of refrig.horsepower (mech) 745.7 wattshorsepower (boiler) 33445.7 btu/hrhorsepower (boiler) 140671.6 calories, gram/minhorsepower (boiler) 9.8097 x 1010 ergs/secondhorsepower (boiler) 13.155 horsepower (mech)horsepower (boiler) 13.1497 horsepower (electric)horsepower (boiler) 13.337 horsepower (metric)horsepower (boiler) 13.149 horsepower (metric)horsepower (boiler) 9809.5 joules/sechorsepower (boiler) 9.8095 kilowattshorsepower (electric) 2547.16 btu/hrhorsepower (electric) 178.298 calories, gram/sechorsepower (electric) 7.46 x 109 ergs/secondhorsepower (electric) 1.0004 horsepower (mech)horsepower (electric) 0.0745 horsepower (boiler)horsepower (electric) 1.01428 horsepower (metric)horsepower (electric) 0.99994 horsepower (metric)horsepower (electric) 746 joules/sechorsepower (electric) 0.746 kilowattshorsepower (metric) 2511.3 btu/hrhorsepower (metric) 632800 calories, gram/hrhorsepower (metric) 7.355 x 109 ergs/secondhorsepower (metric) 0.9863 horsepower (mech)horsepower (metric) 0.07498 horsepower (boiler)horsepower (metric) 0.9859 horsepower (electric)horsepower (metric) 0.98587 horsepower (water)horsepower (metric) 735.499 wattshorsepower (metric) 0.7355 kilowattshorsepower (water) 0.076 horsepower (boiler)horsepower (water) 1.00006 horsepower (electric)horsepower (water) 1.00046 horsepower (mech)horsepower (water) 1.0143 horsepower (metric)horsepower (water) 0.746043 kilowattsinch 25.4 millimetersinch 2.54 centimeterinch 0.08333 feetinch 0.0278 yardsinch 1000 milsinch of Hg 3.37416 kilopascalinch of Hg 0.49116 pound force/inch2

inch of Hg 0.03342 Atmosphereinch of Hg 0.03386 bars

inch of Hg 34.532 grams force/cm2

inch pound force 0.11299 newton meterinch2 645.10 millimeter2

inch2 6.4516 centimeter2

inch3 16.387 millimeter3

inch3 16.39 centimeter3

inch3 0.01639 decimeter3

joule 0.73756 foot* pound forcejoule 0.00095 british thermal unitkilogram 35.274 ouncekilogram 2.20462 poundkilogram 0.001 metric ton (tonne)kilogram 1000.0 gramskilogram force 9.80681 newtonkilogram force/cm2 98.0665 kilopascalkilogram force/cm2 14.22335 pound force/inch2

kilogram force/meter2 9.80665 pascalkilogram/meter3 0.06243 pound/foot3

kilogram/meter3 1.68554 pound/yard3

kilogram/meter3 0.00835 pound/gallonkilogram/meter3 0.00084 ton/yard3

kilogram/meter3 0.001 metric ton/meter3

kilogram/metre 0.67197 pound/footkilometer 0.62137 milekilometer 0.00000000000010 light yearskilonewton 100000000.0 dyneskilopascal 1,000. pascalkilopascal 0.01 barkilopascal 0.14504 pound force/inch2

kilopascal 0.33456 feet of H2Okilopascal 0.29637 inches of Hgkilopascal 0.001 megapascalkilopascal 0.00987 atmospherekilowatts 3414.4 btu/hrkilowatts 2655000 foot-pound force/hrkilowatts 1.34 horsepower (elec&mech)kilowatts 0.1019 horsepower (boiler)kilowatts 1.3596 horsepower (metric)knots 0.868976 kilometers/hourknots 1.688 feet/secondknots 1.1508 miles/hourleagues 18240.0 feetliter 0.03531 foot3

liter 0.001 meter3

liter 1,000. milliliter3

liter 2.113 pintliter 1.057 quartliter 0.2642 gallonliter 1. decimeter3

liter/minute 0.0353 foot3/minuteliter/minute .26417 gallon/minuteliter/second 0.035315 foot3/secondliter/second 15.851 gallon/minuteliter/mm/km/day 10.800 gallons/in/mile/dayliter/mm/km/day 10.800 gallons/in/mile/dayliter/second 0.001 meter3/secondlumens 0.0015 wattslumens/foot2 10.7639 lumens/meter2

lux 0.0929 foot-candlesmegapascal 1,000. kilopascalmegapascal 145.0377 pound force/inch2

megapascal 9.86923 atmosphere




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megapascal 10. barmeter 3.28084 footmeter 1.09361 yardmeter 0.00062 milemeter 0.1988 rodsmeter2 10.76391 foot2

meter2 1.19599 yard2

meter2 0.00025 acremeter2 0.0001 hectareMeter3 0.00081 acre feetmeter3 35.315 foot3

meter3 264.17 gallonmeter3 1.308 yard3

meter3 1,000. literMeter3 0.00081 acre feetmeter3/second 35.315 foot3/secondmeter3/second 15,850.3 gallon/minutemeter3/second 1,00. liter/secondmeter3/second 22.82447 million gallons/daymeters/second2 3.280840 feet/second2

metric ton (tonne) 2,204.6 poundmetric ton (tonne) 1.1023 ton (US)metric ton (tonne) 1,000. kilogrammetric ton/meter3 0.84277 ton/yard3

micrometers 10000.0 angstromsmile (statute) 1,609.344 metermile (statute) 1.60934 kilometermile (statute) 5,280. footmile (statute) 1,760. Yardmile2 640.0 acremiles/hour .447 meter/secmiles/hour 88.0 feet/minutemiles/hour 1.609344 meter/sec miles/hour 1.6093 kilometers/hourmiles/hour 1.852 knotsmiles/hour 1.6093 kilometers/hourmiles/hour 1.852 knotsmillimeter2 0.00155 inch2

millimeter2 0.00155 foot2

millimeter3 0.00006 inch3

milliliters 1.00 cm3

milliliters 0.06102 inch3

milliliters 0.001 litersmilliliters 0.0338 ounces (fld)milliliters 0.00211 pints (fld)millimeters 0.03937 inchesmillimeters 0.00328 footmillimeters 0.01 centimetersmillimeters 0.001 metersmillimeters 39.37 milsmillimeters 1000.0 micronsmillimeters 1000.0 micrometersmillion gallons/day 694.44 gallon/minutemillion gallons/day 0.04381 meter3/secondnewton 0.22481 pound forcenewton 0.10197 kilogram forcenewton meter 0.73756 foot pound forcenewton meter 8.85073 inch pound forcenewton/meter2 0.00015 pound force/inch2

newton/meter2 1.0 pascalohms 100000.0 micro ohmsounce 28.3495 gram

ounce 437.5 grainounce 0.02835 poundounce 0.2835 kilogramounce-force/inch2 4.3942 gram-force/cm2

ounce-force/inch2 0.0625 pound force/inch2

parts/million 0.05842 grains/gallon (US)parts/million 1.0 grams/ton (metric)parts/million 0.0001 percentpascal 1. newton/meter2

pascal 0.00750062 torrpint 0.4732 literpint 0.01671 feet3

pint 28.875 inch3

poise 0.100 pascal-secondpound 7000 grainspound 453.5924 grampound 0.45359 kilogrampound 0.00045 metric ton (tonne)pound 0.0005 tonpound 16. ouncepound 0.0005 tonpound (apoth or troy) 0.82286 pound (avdp)pound force 4.44822 newtonpound force/inch2 6,894.757 pascalpound force/inch2 6.89476 kilopascalpound force/inch2 0.00689 megapascalpound force/inch2 0.07031 kilogram force/cm2

pound force/inch2 6,894.757 newton/meter2

pound force/inch2 0.06895 barpound force/inch2 0.06805 atmospherepound force/inch2 2.307 feet of H2Opound force/inch2 2.036 inch of Hgpound of H2O 0.01602 feet3

pound/foot 1.48816 kilogram/metrepound/foot3 16.01846 kilogram/meter3

pound/foot3 0.0135 ton/yard3

pound/gallon 119.82640 kilogram/meter3

pound/yard3 0.59328 kilogram/meter3

quart 0.9463 literquart 2.0 pintradians 57.2957 degreesrods 502.92 centimetertablespoon 180 drops of liquidteaspoon 60 drops of liquidton 0.90719 metric ton (tonne)ton 907.18 kilogramton/yard3 1,186.553 kilogram/meter3

ton/yard3 1.18655 metric ton/meter3

ton/yard3 74.07407 pound/foot3

torr (Torricellis) 1.0 mm of Hgwatts 0.000948 btu/secwatts 680 lumenswatts 0.00134 horsepoweryard 0.91440 meteryard 91.44 centimeteryard 0.0005682 milesyard2 0.83613 meter2

yard2 9.0 foot2

yard2 0.00021 acreyard3 0.7646 meteryard3 27.0 foot3



Section 7

Section 7B Reference List

Hydraulic HandbookColt IndustriesKansas City, Kansas11th Edition / 1979

Cameron Hydraulic DataIngersol-Dresser PumpsLiberty Corner, NJ18th Edition / 1995

Pure Water HandbookOsmonics Minnetonka, MN1991 Edition

Handbook of PVC PipeUni-Bell PVC Pipe CorporationDallas, TX3rd Edition /1993

Peabody FlowayTurbine Data HandbookFresno, CA 3rd Edition / 1990

Layne Field ManualLayne AssociatesMemphis, TN2nd Edition / 1962

Byron Jackson Pump DivisionBorg Warner Corp.Los Angeles, CA1984 Std. Products Catalog

Hydraulic Institute StandardsHydraulic InstituteCleveland, OH14th Edition / 1983

Engineering Data BookHydraulic InstituteCleveland, OH1st Edition / 1979

Water Supply & SewageSteel / McGheeMcGraw - Hill5th Edition / 1979

Ground Water and WellsJohnson Division, UOP Inc.Saint Paul, MN1st Edition, 1975

Water on Tap: A Consumers Guide to the Nation’sDrinking WaterU.S. EPA, Office of WaterWashington, DC1997 Publication (EPA 815-K-97-002)

Water Well HandbookAnderson - Missouri Water Well & Pump ContractorsAssn., Inc.Belle, MO5th Edition / 1984

Johnston Engineering DataJohnston Pump CompanyGlendora, CAPublication 801 / 1980

Design and Construction of Small Water Systems - AGuide for ManagersAmerican Water Works Asociation1984 Edition

A Guide to Water Well Casing and Screen SelectionRoscoe Moss CompanyLos Angeles, CA 1993 Edition

Submersible Motors & ControlsFranklin ElectricBluffton, ID1997 Edition

Submersible Pump HandbookCentrilift - HughesClaremore, OK3rd Edition / 1981

Agricultural ElectrificationSurbrook / MullinSouth - Western Publishing Co.1985 Edition

Sprinkler IrrigationThe Irrigation AssociationSilver Springs, Maryland4th Edition / 1975

Water Systems HandbookWater Systems CouncilChicago, IL9th Edition / 1987

7-31

7B REFERENCE LIST


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Engineering Manual - Submersible Pumping SystemsGrundfos A/SBjerringbro, Denmark1996 Publication

Hydrology and Geology PrimerLayne - Western Company, Inc.Mission, KS1980 Publication

AC Motor Selection and Application GuideGeneral Electric CompanyFort Wayne, ID1993 Publication

Large Submersible Water Pump ManualWater Systems CouncilChicago, IL1st Edition / 1986

Pumping Industry Technical Information - Product Data(Bulletin C-876)Square D CompanyColumbia, SC1998 Publication

Control Maintenance & TroubleshootingGeneral Electric Co.1978 Training Publication

Introduction to Power Systems for Water andWastewater FacilitiesCalifornia Water Pollution Control Association1991 Training Manual

Vertical Turbine Pumps - Line Shaft and SubmersibleTypes Standard: ANSI/AWWA E101-88American Water Works AssociationDenver, CO1988 Revision

AWWA Standards for Water WellsStandard: AWWA A100-84American Water Works AssociationDenver, CO1984 Revision

AWWA Standards for Disinfection of Water WellsStandard: ANSI/AWWA C654-87American Water Works AssociationDenver, CO1st Edition / 1987

Planning for An Individual Water SystemAmerican Association for Vocational InstructionalMaterialsAthens, Georgia1993 Publication

PSI - Pump Selector for IndustryWorthington PumpMountainside, NJ1980 Edition

Irrigation System Design HandbookRain Bird Sprinkler Mfg. Corp.Glendora, CA1978 Publication



Water Systems Engineering Manual for Groundwater Supply and Special Applications

U.S.A.GRUNDFOS Pumps Corporation 17100 West 118th TerraceOlathe, Kansas 66061Phone: (913) 227-3400 Telefax: (913) 227-3500

CanadaGRUNDFOS Canada Inc. 2941 Brighton Road Oakville, Ontario L6H 6C9 Phone: (905) 829-9533 Telefax: (905) 829-9512

MexicoBombas GRUNDFOS de Mexico S.A. de C.V. Boulevard TLC No. 15Parque Industrial Stiva AeropuertoC.P. 66600 Apodaca, N.L. Mexico Phone: 011-52-81-8144 4000 Telefax: 011-52-81-8144 4010

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Grundfos A2 Water Engineering[1]

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Transcript of Grundfos A2 Water Engineering[1]