01.BAC HBii Maintenance of Crossflow Towers

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Baltimore Aircoil Company

TheValue of Maintaining EvaporativeCooling EquipmentCooling Tower Maintenance and upgrades whats in it for you? Howabout savings in time,money, energy and longer life?

An evaporative heat rejection device enables building owners andoperators to take advantage of the operating cost savingsinherent in water-cooled systems. A well-maintained tower enablesthe entire cooling system to perform at optimum efficiency byconserving both energy and water.

A cooling tower is selected to provide a fluid (usually water) to asystem at a specific design temperature and specific flow rate(GPM). If the delivered temperature of the fluid to the system ishigher than desired, system performance suffers.

Owners gain operating cost benefits when they implement a regular,comprehensive cooling tower maintenance program.

Todays building owners are constantly challenged to keep operating costs down and are anxious to learnways to get the most out of their systems with the least expense. Therefore, owners are motivated topurchase system equipment that is energy-efficient, reliable, and maintenance-friendly. When properlymaintained, water-cooled systems meet these objectives.

The cooling tower is often the forgotten component of the system when it comes to maintenance. Its agood example of the phrase out of sight, out of mind. A newly installed cooling tower reliably delivers thedesign fluid temperature and flow rate. However, since its heat transfer operation creates a hurricane-likeenvironment and is a natural air-washer, the cooling tower needs routine inspection and maintenance tocontinue performing as designed.

A Cost-Saving OpportunityOwners and operators who have a workingknowledge of cooling tower preventive maintenanceand upgrade technology will get the most out oftheir cooling towers. Their efforts can yield benefi-cial results, including: keeping them running smoothly and reliably increasing cooling tower life expectancy maintaining and potentially improvingperformance

This article will take a look at routine maintenanceand suggest ways to improve cooling towerperformance.

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...because temperature matters

Cooling Tower BasicsIn an open circuit cooling tower, warm water fromthe heat source is evenly distributed via a gravityor pressurized nozzle system directly over a heattransfer surface called fill or wet deck, while airis simultaneously forced or drawn through thetower, causing a small percentage of the water toevaporate. The evaporation process removesheat and cools the remaining water, which iscollected in the towers cold water basin andreturned to the heat source (typically awater-cooled condenser or other heatexchanger).

Similarly, in a closed circuit cooling tower or evaporativecondenser, the heat is rejected indirectly from a fluid orvapor flowing through the coil section by sprayingre-circulated water over the coil section, againevaporating a small percentage of the water in theprocess.

The temperature at which the cooled fluid is returned tothe system measures tower performance. Thistemperature can vary depending upon the actual coolingload, water flow, airflow, and the entering air conditions.

Preventive MaintenancePerforming routine preventive maintenance is paramount for consistently achieving the desired temperatureand flow rate, and plays an important role in maximizing cooling tower operating life. Today, thosemanufacturers conscious of the importance of maintenance offer many features which simplify theseprocedures, saving time and money.

To perform properly, all tower components must be kept clean and free of obstructions. The following sectionsdescribe standard maintenance procedures for optimized operation. These procedures can prevent loss ofefficiency in the heat transfer section by maintaining proper water and air flow, as well as preventing corrosionin the cooling tower.


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Maintenance frequency will depend largely upon the condition of the circulating water, the cleanliness of theambient air used by the tower, and the environment in which the tower is operating. More detailedinformation is provided by BACs Operating and Maintenance Manual.

StrainerFundamentally important to the performance of a cooling tower is a method to minimize contact between air& water-borne debris and the system components. This is accomplished with strainers. Strainers in thetower provide a means of keeping debris out of the condenser water loop. Strainers in the cold water basinoutlet prevent debris from reaching the pump. Some towers feature low-pressure drop pre-strainersupstream of the hot water basin to prevent clogging of distribution nozzles. This added feature eliminates theneed to access the distribution nozzles. Both strainers should be routinely inspected and cleaned asnecessary. Some tower designs allow external access to the strainers, which enables maintenance to takeplace without the need to turn off the unit.

Water DistributionThe water distribution system should evenly distribute water over the fill section or coil section via either agravity distribution system or a pressurized spray system. If the water distribution is found to be uneven, thenozzles need to be checked. Clogged nozzles should be cleaned in accordance with the manufacturersrecommendations.

Inspecting cold water basin strainer Hot water basin strainer cleaning

Pressurized spray water distribution

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In a gravity distribution system, the nozzles can be externally accessed, visually inspected and cleaned byremoving the hot water basin covers on the fan deck. Most pressurized spray distribution systems usenozzles and branches held in place by snap-in rubber grommets, which allow easy removal to clean andflush debris.

ColdWater BasinSince some debris will eventually make its way into the cooling tower, the unit design should facilitate debrisremoval. A well-designed cold water basin is sloped toward the strainer to keep dirt (which can acceleratecorrosion) from accumulating throughout the cold water basin. The basin should be kept clean byoccasionally flushing the dirt out of the system through the tower drain. Another way to accomplish this is toinstall basin sweeper piping in conjunction with water filtration or separator devices. Water filtration savesmaintenance costs by reducing the dirt in the cooling water system, which in turn reduces the time required toclean the cold water basins. It also reduces water treatment cost, as water treatment chemicals tend to workmore effectively in clean water. Foreign particles in dirty water can absorb treatment chemicals, thusrequiring the distribution of even more chemicals to properly treat the tower water.

Make-upThough most of the water in the system is recirculated, some water must be added to replace what is lost byevaporation and bleed. Bleed is the defined as the water that is discharged to prevent the accumulation ofsolids in the recirculated water. The make-up water system provides the means to replace the water via amechanical float ball and valve assembly or an electronic water level probe assembly (with solenoid valve),which measures water depth in the cold water basin. The make-up water supply pressure should typically bemaintained between 15 psig and 50 psig to ensure proper valve shut-off and avoid chatter. If the supplypressure is higher than 50 psig, install a pressure reducing valve.

Cold water basin with sweeper piping

Hot water basin with gravity water distribution

Basin sweeper piping


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The operating water level of the cooling tower will vary with system thermal load (evaporation rate), thebleed rate employed, and the make-up water supply pressure. Some tower designs offer access to themake-up assembly external to the cooling tower, which allows easy basin water depth inspection andadjustment without the need to turn off the unit. The tower water level should be set in accordance with theBACs recommendations to ensure no air enters the pump suction, but not so high that water is wastedthrough the overflow when the tower is shut down.

BleedTo prevent the accumulation of solids in the recirculating water, the tower should be equipped with a bleedline (including a metering connection and globe valve) connected to a nearby drain. In a closed circuitcooling tower or evaporative condenser with a circulating pump, a metering valve to control the bleed rateshould be provided at the pump discharge. While a manually adjusted bleed valve is the simplest system,getting the proper bleed rate can be a problem, as cooling tower loads vary throughout the day. Aconductivity meter connected to a solenoid valve solves this problem by maintaining the proper cycles ofconcentration at all times. Also, it is recommended that a separate meter is installed to measure bleedvolume, since less water is discharged to drain than supplied to the cooling tower. This can reduce sewerwater charges.

The bleed rate should be adjusted to prevent an excessive build-up of impurities in the re-circulating water.This is largely dependent upon the local water quality and the evaporation rate. Constant bleed andreplacement with fresh water will prevent the accumulation of impurities. To obtain specificrecommendations, contact a competent water treatment professional for your area.

Mechanical water level control

Electronic water level control

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Mechanical Drive SystemThe mechanical fan drive system has severalcomponents, which should be checkedregularly. Many of these componentsoperate at high speed. Follow properlock-out/tag-out procedures, including lockingout all motor disconnect switches beforeworking on the mechanical system.

Cooling tower fans are typically driven by beltor gear drive systems. Both require routinemaintenance to ensure reliable, trouble-freeperformance. Belt drive systems arepopular, yet reliable, offer single pointadjustment, and have no limit on turndowncapabilities for variable speed applications.If a problem does occur,a simple change ofthe belt is usually all that is required,and replacement components are readily available.

Gear drives provide reliable operation, when properly maintained. If a problem occurs, resolution may bemore involved if a gear box rebuild or replacement is required. Some manufacturers offer both systems tomeet user needs or preferences. To ensure proper operation of a belt drive system, tighten drive belts tomanufacturers specifications. In gear drive systems, the oil level and quality, as well as shaft alignmentshould be checked regularly in accordance with the manufacturers recommendations.

When starting up a new unit, lubrication for the fan shaft bearings is typically not necessary, since most unitsleave the factory already greased. However, for seasonal start-up, purge the fan shaft bearings with newgrease (per manufacturers recommendations). Fan shaft bearings should be lubricated after every 2,000hours of operation or every three months (whichever occurs sooner). Motor bearings should be lubricated asrecommended by the manufacturers instructions. For maximum life, it is best to install motors with a coolingtower duty rating.

The Importance of Clean OperationCooling tower components must be kept clean and free of obstructions. Neglecting the cooling tower will leadto higher than desired return water temperatures to the system, which will result in higher energy usage fromtwo perspectives. First, the system (chiller) will consume more energy because it must operate at a higherthan necessary condensing pressure (head) to satisfy the load. Due to the higher fluid temperatures providedby the cooling tower. As little as 2F higher temperature can result in 6% more energy being consumed bythe chiller. Second, the tower must operate longer at higher fan horsepower while trying to attain the designcold water temperature.

Common Problems: Causes, Effects, and SolutionsRegardless of how often routine maintenance is performed, like any other mechanical component, problemswith cooling towers may sometimes materialize unexpectedly. These include elevated leaving watertemperatures, drift, and corrosion. Should any of these problems occur, follow the actions listed and contactthe cooling tower manufacturers representative or water treatment supplier for assistance.

Check Cooling Load: If the actual cooling load exceeds the design load for which the tower was selectedthe leaving water temperature will exceed the design specification.

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Check Water Flow & Distribution: Visuallyinspect the water distribution system to ensurethe spray distribution nozzles are clean andcorrectly installed and are distributing auniform spray pattern over the fill. Incounterflow towers, measure the pressure atthe cooling tower inlet connection and compareit to the design pressure provided by BAC.For towers with a gravity distribution system,the operating level in the hot water basin(typically between 2 and 5 inches) can becorrelated to a specific flow rate.

Check Air Flow: Cooling towers should be located where an unimpeded supply of fresh air is available tothe air inlets. The cooling tower air discharge should also be at least as high as any surrounding walls toreduce the possibility of hot, moist discharge air being recirculated into the air inlets, creating artificiallyelevated entering wet-bulb and leaving water temperatures. To insure full design air flow, the cooling towerdrive system must be adjusted according to the BACs Operating and Maintenance Manual.

The cooling tower and surrounding area should be examined for air flow restrictions which may causeblockage of the air inlets. Check for clogging or improper distribution of water across the tower fill andcheck for proper operation of capacity control dampers in centrifugal fan towers to ensure proper air flow.The dampers, airfoil blades located in the discharge of the fan housing, help achieve tight temperaturecontrol and energy savings by matching cooling tower airflow to actual load requirements.

Though you may encounter dampers in older existing units, todays towers tend to take advantage ofvariable frequency drive technology (VFDs) to control capacity. VFDs help save energy, do a better job offollowing the load, and help reduce wear and tear on the drive system.

Inspecting spray distribution nozzles

Incorrect orientation of towerand neighboring walls

Proper orientation of towerand neighboring walls

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Check Ambient Conditions: Cooling towers are selected to produce the required leaving water temperatureat the design cooling load and entering wet-bulb temperature. Whenever the actual entering wet-bulbtemperature is higher than design conditions, the leaving water temperature will also be higher. The resultis decreased energy efficiency.

Drift occurs as air flows through the cooling tower and carries water droplets out of the tower. Drift eliminatorsare installed in the discharge stream to remove water droplets from the air. In a properly maintained system,efficient eliminators will reduce drift loss to a negligible percentage of the design flow rate.

If excess drift occurs, check drift eliminators for proper installation, spacing, and overall condition. Examinethe fill for even spacing, to insure there is no clogging or blockage, and check water and air flow as describedabove. Repair or replace eliminators as necessary.

Corrosion is always a concern with cooling towers because of their ability to wash the air of impurities. Theseimpurities cause scale, corrosion, and eventually damage to system components after long-term exposure.

If a constant bleed of the system is ineffective to combat scale or corrosion, chemical treatment may benecessary. A successful chemical or water treatment program should satisfy the specific guidelines set by themanufacturer, provide effective microbiological control, and be compatible with the systems materials ofconstruction as an integral part of the total water treatment program.

Potential airborne impurities and biological contamination (such as Legionella) should be controlled throughthe use of biocides, and such treatment should be initiated at system start-up and continued regularly.ASHRAE has taken proactive steps to understand and deal with Legionella through its popular publication,ASHRAE Guideline 12 2000, entitled Minimizing the Risk of Legionellosis Associated with Building WaterSystems. Contact ASHRAE to secure a copy of this important document. To obtain specificrecommendations of water treatment programs, contact a competent water treatment supplier.

Performance ImprovementsOlder, structurally sound cooling towers can be retrofitted with upgrade kits to: conserve energy restore or improve performance facilitate maintenance

To conserve energy, two-speed motors, variable frequency drives (VFDs) or the ENERGY MISER FanSystem can be added to the mechanical drive system. VFDs offer a wide range of speeds to closely paralleloperating requirements, and pony motors provide the added benefit of redundancy in the event of a motorfailure. A popular energy conservation approach employs a pony motor system with a VFD controlling thelower horsepower motor.

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To improve performance on water distribution systems, kits are available to replace older, smaller nozzles ortroughs with large-orifice, clog-free design. Retrofit fill kits now exist that easily replace the original fill thatmay be clogged with scale or airborne debris. Access platforms can also be added to existingcooling towers to facilitate maintenance.

Conclusion

Paying regular attention to the forgotten system component, the cooling tower, through a regular,comprehensive maintenance program can save time, money and energy while increasing the towers lifeexpectancy. A well-maintained tower is a candidate for retrofit kits designed to enhance performance andlengthen its life. Owners and operators save money through preventative maintenance technology. If youare not regularly performing routine maintenance on your cooling tower, implement a comprehensivemaintenance program today.

For more information on how to get started, contact your local BAC Representative.

Access platforms and ladder

ENERGY-MISER Fan System

Installing retrofit kit

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Series 3000, Series 1500 and FXTCrossflow Cooling Towers

Baltimore Aircoil Company Crossflow Cooling Towers have been designed to give long, trouble-free servicewhen properly installed, operated, and maintained. To obtain optimum performance and maximum servicelife, it is important that a program of regular inspection and maintenance be developed and carried out. Thismanual is published as a guide to establishing such a program

Included in this manual are the recommended maintenance services for start-up, operation, and shutdownand the approximate frequency for each. Note that the recommendations on frequency of service areminimums and where operating conditions are severe, the services should be performed more often. Foreach required service, follow the procedures outlined under the "Maintenance Procedures" section of thismanual. The cooling towers are illustrated in each appropriate section with the major points of inspectionand service identified.

If you need additional information about the operation or maintenance of this equipment that is not coveredin this manual, contact your local BAC Representative. Their name and telephone number are on a labellocated adjacent to the access door. The model and serial number of the unit are also located in this area.You can also visit our web site at www.BaltimoreAircoil.com or contact us at 800-896-8097.

Model Number: _______________________ Serial Number: _________________________

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Table of Contents.........................................................................................Page

General Maintenance Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N11

Safety Precautions &Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N12

Construction Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N13-N15

Recommended Maintenance Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N16

Operation and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N17

Initial and Seasonal Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N17

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N18

Seasonal Shut-down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N18

General Maintenance Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N18

HotWater Basins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N18

ColdWater Basins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N19

Make-UpValves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N20

Fan Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N21

Fan Shaft Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N21

Motor Bases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N22

BALTIDRIVE Power Train Drive System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N23

Fan Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N25

Gear Drive Series 3000 only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N25

Corrosion Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N28

Winter Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N29

Water Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N30

Biological Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N32

General Maintenance Information

The services required to maintain a cooling tower are primarily a function of the quality of the air and water inthe locality of the installation:

Air:The most harmful atmospheric conditions are those with unusual quantities of industrial smoke, chemicalfumes, salt or heavy dust. Such airborne impurities are carried into the cooling tower and absorbed by therecirculating water to form a corrosive solution.

Water:The most harmful conditions develop as water evaporates from the cooling tower, leaving behind thedissolved solids originally contained in the make-up water. These dissolved solids may be either alkaline oracidic and, as they are concentrated in the circulating water, can produce scaling or accelerated corrosion.

The extent of impurities in the air and water determines the frequency of most maintenance services and alsogoverns the extent of water treatment which can vary from a simple continuous bleed and biological control toa sophisticated treatment system. (See sections on "Water Treatment and Biological Control.")

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Safety Precautions

WARNING: Before performing any maintenance or inspection, or performing service on or near fans,drives, motors or inside the unit, make certain that all power has been disconnected and locked in theoff position.

WARNING: The top horizontal surface of the unit is not intended for use as a walking surface orworking platform. If access to the top of the unit is desired, the purchaser/end-user is cautioned to useappropriate means complying with applicable safety standards of governmental authorities.

WARNING: When the fan speed of the unit is to be changed from the factory set speed, includingchanges achieved by the use of a variable fan speed device, steps must be taken to avoid operation ator near the fans critical speed which could result in fan failure and possible personal injury ordamage. Consult with your local BAC Representative on any such applications.

WARNING: The recirculating water system may contain chemicals or biological contaminants, includingLegionella, which could be harmful if inhaled or ingested. Personnel exposed directly to the dischargeairstream and the associated drift mists, generated during operation of the water distribution systemand/or fans, or mists produced by high pressure water jets or compressed air (if used to cleancomponents of the recirculating water system), must wear respiratory protection equipment approvedfor such use by governmental occupational safety and health authorities.

Safety PrecautionsOnly qualified personnel may operate, maintain, and repair this equipment. All such personnel must bethoroughly familiar with the equipment, the associated system and controls, and procedures in this manual.Use proper care, procedure, and tools when handling, lifting, installing, operating, maintaining, and repairingthis equipment to prevent personal injury and/or property damage.

CAUTION: StorageBAC units are typically installed immediately after shipment, and many operate year round. However, if theunit is to be stored for a prolonged period of time either before or after installation, certain precautionsshould be observed. For instance, covering the unit with a clear plastic tarpaulin during storage can trapheat inside the unit, potentially causing damage to the fill and other plastic components. If units must becovered during storage, an opaque, reflective tarp should be used. Consult with your local BACRepresentative for additional recommendations on long-term storage. For normal seasonal shutdowns, referto the applicable section in this manual.

CAUTION: All electrical, mechanical, and rotating machinery are potential hazards, particularly for thosenot familiar with there design, construction and operation. Accordingly, use appropriate lockout proceduresand adequate safeguards (including the use of protective enclosures where necessary) should be taken withthis equipment both to safeguard the public from injury and to prevent damage to the equipment, itsassociated system, and the premises.

CAUTION: This equipment should never be operated without all fan screens, access panels, andaccess doors in place. For the protection of authorized service and maintenance personnel, install alockable disconnect switch located within sight of the unit on each fan and pump motor associated with thisequipment.

Freeze Protection: Mechanical and operational methods must be employed to protect these productsagainst damage and/or reduced effectiveness due to possible freeze-up. Please refer to the product catalogor contact the local BAC Representative for recommended protection alternatives.

Warranties: Please refer to the Limitation of Warranties applicable to and in effect at the time of thesale/purchase of these products. Described in this manual are the recommended services for start-up,operation, and shut down and the approximate frequency for each of BACs Crossflow Cooling Towers.


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Figure 1a

Figure 1b

Fan Guard

Top WaterInlet

BALTIDRIVE Power TrainFan System

BACross Fillwith Integral Drift

Eliminators

Make-up ValveAdjustable Float

Fan Deck

Hot WaterBasin & Cover

Air InletLouvers

Cold WaterBasin

Casing

SuctionStrainer

Water OutletConnection

Series 3000 Construction details:

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Series 1500 Construction Details:

Fan and Fan Guard Hot Water Basinand Cover

Water Inlet withPrestrainer

Air Inlet Louvers

BACross Fillwith Integral Drift

Eliminators

Make-up ValveAdjustable Float and

Suction Strainer

Cold Water Basin

Figure 2a

Figure 2b


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Figure 3a

Drives

Motor

Air InletCylinder

Axial Fan

Fan ShaftAnd Bearings

Water OutletConnection

Strainer

AdjustableFloat

Water Make-UpValve Assembly

Access Door

BACross Fill IntegralDrift Eliminators

Hot Water Inlet

Hot WaterDistribution Basin

Plastic MeteringOrifices

FXT Construction Details:

Figure 3b

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WARNING: Before performing any maintenance or inspection, make certain thatall power has been disconnected and locked in the off position.

Notes:1. Recommended service intervals are for typical installations. Different environmental

conditions may dictate more frequent servicing.

2. When operating in ambient temperatures below freezing, the cooling tower should beinspected more frequently (see Winter Operation).

3. Tension on new belts must be readjusted after the first 24 hours of operation andquarterly thereafter.

Table 1. Recommended Maintenance Services for Crossflow Cooling Towers (1)

Type Service Start-Up Monthly Quarterly Annually Shutdown

Inspect general condition of the tower (2) and checkunit for unusual noise of vibration

X X

Inspect and clean as necessary:

Cold and hot water basins/spray nozzles X X

Air inlet louvers X X

Check and adjust water level in basins X X

Check operation of make-up valve X X

Check and adjust bleed rate X X

Optional BALANCE CLEANChamber Inlet Strainer(Series 3000)

X X X

Mechanical equipment system:

Check Belt Condition X X

Adjust Belt Tension (3) X X

Lubricate Fan Shaft Bearings X X X

Lubricate Motor Base Adjusting Screw X X X

Check and Lubricate Optional Gear Drive See gear drive section for detailed instructions and schedule

Check Drive Alignment X

Check General Condition of the Fan x

Check & Unplug Fan Drain Holes (Hollow Blade Fans) x

Check Fan for Uniform Pitch x

Check Fan for Rotation without Obstruction X X

Check Fan Motor for Proper Rotation X

Check Motor Voltage and Current X X X

Clean Fan Motor Exterior X X

Drain Basins and Piping X X

Inspect Tower Finish X


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Operation and MaintenanceInitial and Seasonal Start-up:

Prior to initial start-up or after a shut-down period, the cooling tower must be thoroughly inspected andcleaned:

1. Clean all debris, such as leaves and dirt, from inside the tower, the air inlets and the hot water basins.2. Remove, clean and install the inlet pre-strainer on Series 1500, and the inlet strainer on Series 3000

Cooling Towers provided with the optional BALANCE CLEAN Chamber.3. Drain the cold water basin (with basin strainers in place) and flush to remove accumulated dirt.4. Remove the suction strainer, clean and reinstall.5. Turn the fan(s) by hand to insure rotation without obstruction.6. Bump the fan motor(s) and check for proper fan rotation.7. At seasonal start-up, check and adjust the belt tension on the fan drive system. Note, during initial

start-up, the belt tension may not require adjustment since the drive has been properly tensioned at thefactory prior to shipment.

8. Check float operated make-up valve to be sure it is operating freely.9. Lubricate the fan shaft bearings prior to seasonal start-up.10. At start-up, when the cold water basin is completely drained, fill the cold water basin with fresh water to

the overflow level. For new installations, initiate the biocide water treatment program at this time (Seesection on "Biological Control"). At seasonal start-up, and following a shutdown period of more than 3days, resume the biocide treatment program or administer a shock treatment of appropriate biocides priorto operating the cooling tower fans to eliminate accumulated biological contaminants (See section on"Biological Control").

11. Set the float on the make-up valve to close the valve when the float is approximately 1/2" below theoverflow level.

12. Balance flow to the hot water basin(s) by adjusting the flow balancing valves (provided by others oroptionally supplied by BAC) on Series 3000, Series 1500 and FXT Cooling Towers. This is not requiredon Series 3000 Cooling Towers equipped with the optional EASY CONNECT Piping Arrangement withthe BALANCE CLEAN Chamber. However, multi-cell arrangements will require flow balancing betweencells to obtain even water distribution.

13. Open the valve in the tower bleed line and adjust bleed.14. Check the voltage and current of all three legs of the fan motor. The current should not exceed the

nameplate rating. Note: Current should be measured during warm ambient conditions and with a heatload on the tower. After prolonged shutdowns, the motor insulation should be checked with an insulationtester prior to restarting the motor.

WARNING: No service work should be performed on or near the fans, motors, and drives or inside theunit without first ensuring the fan and pump motors have been disconnected and locked out.

CAUTION: Rapid on-off cycling can cause the fan motor to overheat. It is recommended that the controls beset to allow a maximum of 6 on-off cycles per hour. When using a 2-speed motor, the starter should include a15-second time delay when switching from high speed to low speed.

Inverter duty fan motors, furnished in accordance with NEMA Standard MG.1 Part 31, are required forapplications using variable frequency drives for fan motor control.

AFTER 24 HOURS: After 24 hours of operation under thermal load, the following services should beperformed:

1. Check the tower for any unusual noise or vibration.2. Check the operating water level in the hot and cold water basins and adjust balancing valves.3. Adjust make-up valve.4. Readjust the belt tension.

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Operation:During operation, the tower should be inspected, cleaned, and lubricated on a regular basis. The requiredservices and the minimum recommended frequency for each are summarized in Table 1 on page N16 of thisbulletin.

Seasonal Shutdown:The following services should be performed whenever the cooling tower is to be shutdown for more than3 days:

1. Drain the cold water basin and all piping that will be exposed to freezing temperatures.2. Clean and flush the hot and cold water basins with the basin strainers in place. Leave the cold waterbasin drain open so rain and melting snow will drain from the tower. For Series 3000 Cooling Towers withthe optional BALANCE CLEAN Chamber, clean and flush the inlet strainer.

3. Clean the basin strainers and reinstall.4. Cover the fan discharge opening to keep out dirt and debris on Series 3000 and Series 1500 CoolingTowers.

5. Lubricate the fan shaft bearings and motor base adjusting screw.6. Close the shut-off valve in the make-up water line (supplied by others) and drain all exposed make-upwater piping.

7. Inspect the integrity of the corrosion protection system on the steel portion of the tower. (See section on"Corrosion Protection").

8. On Series 1500 Cooling Towers, inspect the anti-skid tape on the internal walkway and replace asnecessary if deterioration or lifting is observed.

9. Secure the fan motor starting device in the off position. If inspection or repair requires service personnelto work around either the fan or drives during shutdown, a personal safety hazard exists if this precautionis not taken.

WARNING: No service work should be performed on or near the fans, motors, and drives or insidethe unit without first ensuring the fan and pump motors have been disconnected and locked out.

General Maintenance ProceduresHotWater BasinThe system water enters the cooling tower through the hot water basin(s) Figure 4a. At design flow, theoperating level should not be less than two (2) inches or greater than five (5) inches deep. Quarterly, ormore often as required, remove any dirt or debris which may clog the nozzles. Seasonally clean and flushthe hot water basin with fresh water.

HotWater Basin and Integral Pre-Strainer (Series 1500):The hot water basin, the integral pre-strainer and the nozzles must be kept clean Figure 4b. The Series1500 water inlet is furnished with a removable pre-strainer at the inlet to prevent debris from entering the hotwater basin. This strainer should be periodically cleaned as shown in the Recommended MaintenanceSchedule. This is accomplished by removing the access panel on top of the unit and then removing thestrainer basket.

Figure 4a - Series 3000 hot water basinFigure 4b - Series 1500 hot water basin

and pre-strainer


N19


Optional BALANCE CLEAN Chamber (Series 3000):The water to be cooled enters the tower through a single connection and passes through the BALANCECLEAN Chamber. This device is equipped with an internal strainer. The bottom of the BALANCE CLEANChamber is a capped cleanout connection. This can be used to periodically purge the BALANCE CLEANChamber of dirt and debris as indicated in the Recommended Maintenance Schedule. This is accomplishedby un-bolting and temporarily removing the chamber bottom plate and inspecting the strainer for dirt anddebris, see Figure 5.

ColdWater Basin and Suction Strainer:As the water circulating though the tower is cooled, it collects in the cold water basin and passes through thesuction strainer into the system. The operating water level is controlled by the make-up valve and should bemaintained at the operating water level shown in Table 2.

The operating water level in the cold water basin will vary with system thermal load (evaporation rate), thebleed rate employed, and the make-up water supply pressure. Because the typical winter load is less thanthe summer load, the winter evaporation rate is frequently less than the summer evaporation rate. With thisreduced evaporation rate in winter, the water level in the cold water basin will increase unless the float isre-adjusted. The operating water level should be checked monthly and the float re-adjusted as necessary tomaintain the recommended operating level.

The water level in the cold water basin of units designed for remote sump operation is a function of thecirculating water flow rate, along with quantity, location, size and configuration of the water outlet piping.Units designed for remote sump applications are not supplied with a water make-up assembly and the basinoperating level is not adjustable during operation.

The cold water basin should be inspected regularly. Any trash or debris which may have accumulated in thebasin or on the strainers should be removed and, if necessary, the float adjusted to maintain the designoperating level. (See Table 2, "Cold Water Basin Operating Levels").

Table 2: ColdWater Basin Operating Levels

The entire cold water basin should be drained, cleaned, and flushed quarterly, or more often if necessary,with fresh water to remove the silt and sediment which normally collects in the basin.

Figure 5 Strainer for optionalBALANCE CLEAN Chamber

Series 3000Model Number

Height of Water inthe Cold WaterBasin (in.)

Series 1500Model Number


FXTModel Number


3420A - 3501A3552A - 31301A

8 3/49 3/4 All Models 7

6 - 1116 - 3338 - 536

4 1/256

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It is important to note that the same maintenance applies to galvanized steel basins, basins protected by theBALTIBOND Corrosion Protection System, and stainless steel basins. If not removed periodically, sedimentcan become corrosive and cause deterioration of the protective finish of metallic basins. When flushing thebasin, the strainers should be left in place to prevent the sediment from re-entering the tower system. Afterthe basin has been flushed, the strainers should be removed, cleaned, and replaced before refilling thebasin with fresh water.

WARNING: Openings and/or submerged obstructions may exist in the bottom of the cold water basin.Use caution when walking inside this equipment.

Make-UpValve:A float-operated mechanical water make-up assembly is furnished as standard equipment on the coolingtower (unless the unit has been ordered with the optional electric water level control package or is equippedfor remote sump application). The mechanical make-up assembly is located within easy reach from theaccess door at the connection end of the unit on FXT and Series 3000 Cooling Tower. The mechanicalmake-up valve is easily accessible from the louver face of the Series 1500 Cooling Tower. The standardmake-up assembly consists of a bronze make-up valve connected to a float arm assembly and is actuatedby a large diameter polystyrene-filled plastic float. The float is mounted on an all-thread rod held in place bywing nuts. The operating water level in the cold water basin can be adjusted by repositioning the float andall-thread rod using the wing nuts provided.

The make-up assembly should be inspected monthly and adjusted as necessary. The valve itself should beinspected annually for leakage and the valve seat replaced if necessary. The make-up water supplypressure should be maintained between 15 and 50 psig for proper operation of the valve.

To set the initial basin water level, adjust the wing nuts so that the make-up valve is completely closed whenthe water level in the cold water basin is 1/2" below the overflow connection. Under design thermal load andwith average water pressure (15 to 50 psig) at the valve, this setting should produce the operating waterlevels stated in Table 2.

Note that if the thermal load is less than the design load at the time of unit start-up, the procedure mayproduce operating levels greater than these shown in table 2. It may be necessary to re-adjust the float inorder to attain the recommended operating level. The unit cold water basin should be closely monitored andwater level adjusted as necessary during the first 24 hours of operation.As an option, an electric water level control package is available in lieu of the mechanical make-upassembly. The package consists of a probe-type liquid level control assembly and a slow-closing solenoidvalve. Stainless steel electrodes, factory-set at predetermined lengths, extend from an electrode holder intothe cold water basin. These electrodes should be periodically cleaned to prevent accumulations of scale,corrosion, sludge or biological growth which could interfere with the electrical circuit.

Series 3000, Series 1500 & FXTmechanical make-up valve


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With the electric water level control package, the water level is maintained at the recommended operatinglevel regardless of the system thermal load. Therefore, it is not necessary, nor is it recommended, that theoperating level be adjusted. During the start-up of units equipped with the electric water level control package,the control unit should be bypassed in order to fill the unit 1/2" below the overflow connection.

Operation at the recommended water level will ensure that the unit basin contains sufficient water volume toprevent air entrainment in the circulating pump during system start-up and to provide sufficient excess basincapacity to accept the total system pull-down volume. ("Pull-down volume" is defined as that quantity of watersuspended in the tower during operation plus that contained in the hot water basin, fill, external piping, andany heat exchangers which could drain to the tower cold water basin when the circulating pump is shut down.)Fan Motors:The standard fan motors used on BAC Cooling Towers are Cooling Tower Duty Motors, either a TEAO (TotallyEnclosed, Air Over), or a TEFC (Totally Enclosed, Fan Cooled) configuration, with permanently lubricated ballbearings and special moisture protection on the bearings, shaft, and windings. The only servicing requiredduring operation is to clean the outside surface of the motor at least quarterly to ensure proper motor cooling.Additionally, after prolonged shutdowns, the motor insulation should be checked with an insulation tester priorto restarting the motor.

Series 1500 & Series 3000: The fan motor(s) is totally enclosed, air-over (TEAO), single-speed, single-wind-ing, reversible "squirrel cage", ball bearing type, designed specifically for evaporative heat rejection service.Series 3000 (Option): The fan motor(s) is totally enclosed, fan-cooled (TEFC) ball bearing type,single-speed, single-winding, and suitable for outdoor service. A TEFC motor(s) is standard when the coolingtower is provided with gear drive and externally mounted motor(s).

FXT: The fan motor(s) is totally enclosed, fan-cooled (TEFC), single-speed, single-winding, suitable foroutdoor service.

WARNING: When the fan speed of the cooling tower is changed from the factory-set speed, includingchanges achieved by the use of a variable fan speed control device, steps must be taken to avoidoperating at or near the fans "critical speed", which could result in fan failure and possible injury ordamage. On most fan drive systems, it is not uncommon for one or more resonant speeds to exist.Consult with your local BAC Representative on any such applications.

Fan Shaft Bearings:The fan shaft is supported by two pillow block ball bearings, each equipped with a lubrication fitting and aslinger/locking collar to keep out moisture. The bearings should be lubricated as follows:

Initial Start-Up: Normally, no lubrication is required since the bearings have been lubricated at the factoryprior to shipment. However, if the cooling tower has been stored at the job site for more than one year,bearings should be lubricated with new grease before initial operation. When lubricating, purge the old greasefrom the bearing by gradually adding grease until a bead of new grease appears at the seal on the undersideof the bearing.

Seasonal Start-Up: Purge both bearings with new grease prior to start-up.

Operation: Lubricate bearings every 2,000 hours of operation or once every three months, whicheveroccurs first.

Seasonal Shutdown: Purge bearings with new grease prior to any prolonged storage or downtime.

CAUTION: The fan shaft bearing should be lubricated only with a hand grease gun. Do not use high pressuregrease guns since they may rupture the bearing seals. Lubricate the bearings with only one of the followingwater resistant greases which are suitable for ambient temperatures ranging from 65F (-53.9C) to +250F(121.1C) .

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Amoco - Rycon Premium #3 Chevron - SRIMobil - Mobil #28 Mobil - SHC 32Shell - Alvania 3 Shell - Dolium "R"Texaco - Regal AFB 2

Locking Collars (FXT Cooling Towers)Each eccentric locking collar should be checked every six months to ensure that the inner bearing race issecured to the fan shaft. The locking collar can be set using the following procedure. (See Figures 6 & 7).

1. Loosen the set screw.2. Using a drift pin or centerpunch, tap the collar (in the hole provided) tangentially in the directionof rotation while holding the shaft.

3. Retighten the set screw.

Adjustable Motor Base:The motor base slides and adjusting screws (see Figures 8, 9, 10, 11, 12 & 13) should be coated twicea year using a good quality grease such as those recommended for lubricating the fan shaft bearings.

Figure 6 Figure 7FXT Bearing with locking collar

Figure 8- Adjustable Motor BaseFXT Models 26-68.

Figure 9- Adjustable Motor BaseFXT Models 74-142 and 230-284.

Figure 10- Adjustable Motor BaseFXT Models 160-268 and 320-536.


N23


Fan Belt Adjustment (3000, 1500 and FXT):Models FXT-26 thru FXT-536 use V-belts, Series 1500 and Series 3000 use powerbands. Belt tension shouldbe checked and adjusted at least quarterly, or as needed. To properly adjust the belt tension, position the fanmotor so that the belt will deflect 1/2 when moderate pressure (approximately 15 lbs.) is applied midwaybetween the sheaves.

NOTE: There should be no "chirp" or "squeal" when the fan motor is started.

The position of the fan motor can easily be changed by adjusting the rod which extends from the frame to themotor base. Loosen the locknut on top of the frame and rotate the nut under the frame with a wrench asnecessary. Then retighten the locknut (see Fig. 12 and 13).

NOTE: Direct drive units (FXT-6 thru FXT-20) do not employ fan shaft bearings, adjustable motor bases, fandrives or belts. The fans are driven directly by the motor and there is never a need for any adjustment.

BALTIDRIVE Power Train (SERIES 1500 and SERIES 3000):The BALTIDRIVE Power Train consists of a specially designed belt, with corrosion-resistant fan motorsheaves (see Figures 11 and 12). The solid-backed, multi-groove, neoprene/polyester belt provides thepremium quality necessary for cooling tower service. The corrosion-resistant sheaves extend the life of thebelt by minimizing any possibility of rust or corrosion. These components provide a highly reliable system withlow maintenance requirements. The only service required on the BALTIDRIVE Power Train is to periodicallycheck the condition of the belt and, when necessary, adjust the tension. The recommended service intervalsare specified below:

Initial Start-Up:No servicing is required prior to initial tower start-up since the drive has been tensioned and aligned at thefactory.

Seasonal Start-Up:Re-adjust the tension on the belt.

Operation:After the initial tower start-up or the installation of a new belt, the tension must be readjusted after the first 24hours of operation. Thereafter, the condition of the belt should be checked monthly and the tension adjustedas necessary, but at least once every three months.

Figure 11 Series 1500adjustable motor base

Figure 12 Series 3000adjustable motor base

Figure 13 FXTfan belt adjustment

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To check the belt tension, place a straight edge along the belt from sheave to sheave as shown in Figure15a or use a tape measure as shown in Figure 15b to measure belt deflection. Apply a moderate force byhand (approximately 40 lbs) evenly across the width of the belt in the center of the span between thesheaves. If the belt deflects between 1/4" and 3/8" as shown in Figures 15a and 15b, the belt is adequatelytensioned.

If belt tensioning is required, proceed as follows:

1. Loosen the lock nut on the motor base adjusting screw.2. Turn the motor base adjusting screw clockwise to tension the belt, or counterclockwise to relieve belttension. During adjustment of belt tension, the drives should be rotated several times by hand toevenly distribute the tension throughout the belt.

3. When the belt is properly tensioned, retighten the locking nut on the motor base adjusting screw.NOTE: There should be no "chirp" or "squeal" when the fan motor is started.

The drive alignment should be checked annually to ensure maximum belt life. This can be done by placing astraight edge across the driver and driven sheaves as shown in Figure 16a for standard drives and in Figure16b for ENERGY-MISER Fan System drives. When the drives are properly aligned, the straight edge willcontact all four points as indicated. There should be no more than 1/16" deviation from four points ofcontact. If realignment is necessary, loosen the motor sheave and align it with the fan sheave. Allowapproximately 1/4" for draw-up as the bushing screw is retightened.

Figure 15a Figure 15bBelt Tension

Figure 16a Standard Drive Alignment Figure 16b ENERGY-MISER Fan SystemDrive Alignment


N25


Fan Assembly:

1. If the unit is already in operation, check while the fan is running for any unusual noise or vibration.2. With the fan off and the motor locked out and tagged, check the general condition of the fan:

a. Inspect for any loose or missing bolts in the fan shaft bushing, the fan hub and the fan shaftbearings.

b. Check the fan blades for looseness, first by twisting the blade by hand and then by moving theblade tip up and down.There should be no play or slippage whatsoever.

c. Inspect along each blade for excessive scale build-up that could cause vibrationd. Check each blade, in the area of the shank, for any signs of cracking. If cracking isfound, the fan should be locked out immediately. Contact you local BAC Representative forassistance.

3. Tip Clearance Check the clearance between the tip of the blade and the fan cowl. This should bebetween 3/8 and 1-1/8.

4. Drain Holes On hollow blades, the drain hole in the blade tip should be unobstructed. (Hint: Use apiece of wire to probe the hole).

5. Blade Pitch Check to ensure that the blades are all at the same pitch. If uncertain, measure the pitchwith an inclinometer. All blades should be within +/- 1/2.

6. Rotation Turn the fan by hand to ensure that it moves freely with no rough spots, binding or othermalfunctions that could cause vibration or fan motor overload. While rotating the fan, check the bladetracking. All blades should track within a 1" band at any single point around the cowl.

7. Direction of Rotation On initial start up, or if the fan motor has been rewired for some reason, bumpthe fan motor and note the direction of rotation. It should rotate in the direction indicated by the arrowon the fan cowl.

8. Operation On initial start up, run the fan in the manual position for several minutes and check for anyunusual noises or vibration.

Gear Drive System (Series 3000):Inspection: All gear drives are shipped with oil installed. The initial oil level should be at or near the middle ofthe oil level sight gage, and should be maintained so that the oil level is always visible in the sight gagewindow when the unit is idle or not energized and the oil is at ambient temperature. See Figure 17 forlocations of the gear drive fittings. Prior to start-up, check all fittings on the gear drive to ensure that there areno visible leaks. The standard oil provided in BAC gear drive systems is mineral oil. Synthetic lubricants arealso available as an option. Refer to the unit nameplate for the oil type provided with the gear drive system.

Gear drive units with internally mounted motors are properly installed and aligned at the factory. All fastenersare factory tightened, but should be checked after installation. For units supplied with externally mountedmotors, install and align the motor and driveshaft in accordance with the customer assembly instructionsincluded with the unit. It is recommended that alignment and all external fasteners be rechecked after twoweeks of operation.

Figure 17 Single reduction gear drive

Breather Plug

Oil Sight Glass

Drain Plug

Name Plate

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Operation: No special break-in procedures, other than rechecking alignment and external fasteners, arenecessary except as noted under the Lubrication section.

Excessive noise or vibration at initial operation is an indication of one or more of the following:

1. Misalignment2. Imbalance of the fan or other rotating parts3. Improperly adjusted fan blades4. Operation at mechanical equipment resonant speed

WARNING: If noise or vibration persists, shut the unit down and correct the cause before furtheroperation.

On installations with two speed motors, when slowing from high speed, allow a minimum 15 second timedelay for the fan to slow down before energizing the low-speed winding.

CAUTION: When reversing the direction of rotation, allow the fan to come to a complete stop before restart-ing the motor.

Variable Frequency Drive Operation:

CAUTION: On installations with variable speed motors, do not operate standard gear drives below 450 RPMmotor speed (gear input speed). Modifications to the lubrication system or special gear oil pumps arerequired for operation at input speeds lower that 450 RPM.

CAUTION: Continued operation at a resonant speed condition will result in torsional vibrations within thegear which can be damaging to all components of the system. The most common indicator of torsionalvibrations is an unusual rumbling or grinding noise from the gear drive at a sharply defined speed. Thenoise will disappear when the speed is increased or decreased. This noise is not indicative of a defect butresults when the vibratory torque exceeds the drive torque causing the gear teeth to separate and clashtogether very rapidly. On variable speed applications, operation close to a resonant speed should beavoided and transition through a resonant speed range should be swift.At start-up, the variable frequency drive should be increased through the range from 0 RPM to maximummotor speed. As the speed is increased, the gear drive system should be observed to note the onset ofany unusual rumbling or grinding at specific speeds. These resonant speeds (+/- 10%) should be "lockedout" by the variable speed drive. Please refer to the variable frequency drive manufacturersrecommended start-up procedure for further information.

Lubrication: Use only rust and oxidation inhibited gear oils in accordance with AGMA (American GearManufacturers Association), Standard 9005-D94. For general operating conditions, AGMA lubricant numberand corresponding ISO Grade should be as shown in Table 3 for mineral oils and Table 4 for syntheticlubricants (reference the cooling tower nameplate to determine if synthetic lubricant was furnished). Foroperation under extremely hot or cold ambient conditions, contact your local BAC Representative for specificrecommendations.

Start-up at an ambient temperature less than 20F (-7C ) requires either the use of lube oil heaters (formineral oils) or synthetic oil (ambient temperature to -20F (-29C)). Each unit has provisions for an internaloil reservoir heater. Heaters and synthetic oil are extra cost accessories and can be ordered with new unitsor may be ordered and installed in existing units.

The vertical and horizontal shafts are equipped with grease-lubricated dual seals. Relubrication is notrequired.


N27


Table 3: Recommended Mineral Oils

Table 4: Recommended Synthetic Lubricants

** List of brand names is for purpose of identifying types and is not to be construed as exclusiverecommendations.Synthetic Lubricants: Synthetic lubricants offer advantages such as extended service life, a broaderoperational temperature range, reduced friction, and the ability to maintain a higher film strength which canextend the service life of the gear drive. For general operating conditions, AGMA lubricant number andcorresponding ISO Grade should be as shown in Table 4. Synthetic lubricants can be made of various basestocks which are incompatible with certain gear drive components; therefore, any synthetic lubricant not listedin this manual should not be used without first consulting your local BAC representative.

Change Interval: The original oil should be replaced after 500 hours or four weeks of operation, whichevercomes first. It is recommended that the oil be drained through the drain plug when it is at operatingtemperature. Refill the drive through the air breather port with the recommended type (Tables 3 & 4) andamount of lubricant (Table 5). See Figure 17 for locations of the gear drive fittings.

Maintenance: Check oil level weekly with the unit idle. Add oil if level is below oil level indicator. Normal oper-ating oil capacity of each gear drive is given in Table 5. Specific gear model number for each unit can also befound in Table 6, or on the gear drive nameplate. Daily visual inspections and observation for oil leaks andunusual noises and vibrations are recommended. If any of these occur, the unit should be shut down and thecause found and corrected.

Periodic checks should be made to ensure the proper alignment of all system components and that all boltsand external fasteners are tight.

Special precautions are necessary during periods of inactivity. When the internal parts are not continuallybathed by the lubricant as during operation, the gear drive is susceptible to corrosion. For best results, let thedrive cool for approximately four hours after shutdown, start the fan and let run for approximately five minutes.This will coat the internal parts of the drive with cool oil. Thereafter run the fan for five minutes once a weekthroughout the shutdown period to maintain the oil film on the internal parts of the gear drive.

On seasonal shut down, it is recommended that the drive unit be completely filled with oil. This can beaccomplished by filling through the air breather port. Cover the drive with a tarpaulin or other protective covering.

Ambient Temperature at Gear Drive: 20F to 120F (-7C to 49C)AGMA Lubricant Number: 5ISO Grade: 220Manufacturer Oil Type**

Atlantic Richfield Co.Chevron Oil Co.Cities Service Oil Co.ConocoExxon Co.Gulf Oil Co.Mobil Oil Co.PennzoilPhilips Petroleum Co.Shell Oil Co.Sun Oil Co.Texaco Inc.Total

Duro 220Machine Oil AW 220Citgo Pacemaker 220Hydroclear Multipurpose R & O Oil 220Teresstic 220Harmony 220DTE Oil BBPennzbell R & O 220Magnus 220Morlina 220Sunvis 999Regal 220 R & O, Code 1531Carter 220

Ambient Temperature at Gear Drive: -20F to 150F (-29C to 66C)AGMA Lubricant Number: 5SISO Grade: 220Manufacturer Oil Type**Chevron Oil Co.ConocoExxon Co.Mobil Oil Co.Shell Oil Co.

Clarity 220 SyntheticSyncon 220 - R70 OilTeresstic SHP 220SHC 630Omala RL220

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CAUTION: Drain the excess oil before returning the gear drive to service.By following the above procedures, each BAC gear drive system will provide years of useful service.

Table 5 Normal Operating Oil Capacity Table 6 Gear Model/Unit

Corrosion ProtectionBAC cooling towers are constructed of corrosion-resistant materials. The fill is made of an inert syntheticmaterial, which requires no protection against rot, decay, rust or biological attack. Other materials used inconstruction of the equipment, which are listed below, should be inspected regularly.

Galvanized Steel ComponentsGalvanized steel components should be inspected for blemishes or corrosion. Affected areas should be wirebrushed and recoated with a cold galvanizing compound such as Zinc Rich Compound (ZRC).

BALTIBOND Corrosion Protection System ComponentsGalvanized steel components protected with the BALTIBOND Corrosion Protection System may developscratches, scrapes or blemishes. These may be touched up with a repair kit (BAC Part No. 16-133P). In theunlikely event that the damage is more extensive than simple scratches or minor blemishes, contact your localBAC Representative.

Stainless Steel ComponentsStainless steel components should be inspected for signs of blemishes or corrosion and cleaned withstainless steel wool as necessary. If more extensive corrosion is prevalent, contact your local BACRepresentative.

Fiberglass Reinforced Polyester (FRP) ComponentsSeries 3000 Cooling Towers are provided with FRP casing panels as standard. These components should beinspected for accumulation of dirt and cleaned with soap and water as necessary.

Gear Model Gallons Liters

65 0.5 2

85 1 4

110 2 8

135 3 11

155 5 19

175 5.5 21

Unit Model (HP) Gear Model Unit Model (HP) Gear Model

3240A 65 3728A 110

3272A 65 3781A 110

3299A 85 3828A 110

3333A 65 3872A 110

3333A (20) 85 3923A 110

3358A 85 3970A 135

3379A 85 3985A 110

3412 A 85 31056A 135

3436A 85 3583A 110

3455A 85 3618A 110

3482A 85 3676A 110

3527A 110 3725A 110

3473A 85 31132A 110

3501A 85 31132A (50) 135

3552A 85 31132A (75) 155

3604A 110 31213A 135

3648A 110 31213A (75) 155

3672A 110 31301A 175


N29


Winter OperationBAC cooling towers can be operated at ambient temperatures below freezing provided proper operatingmethods are established and diligently followed.

Precautions that must be taken to ensure satisfactory operation include:

Freeze protection of the water in the cold water basin and elimination of water in the optional BALANCECLEAN Chamber (Series 3000) and in all internal piping when the tower is idle.

Freeze protection must be provided for the cold water basin during shutdown since ice formation in thebasin can severely damage the cooling tower. A remote sump located indoors in a heated space is an idealmethod since the water in the tower and connecting piping will drain by gravity whenever the circulatingpump is stopped. Where a remote sump arrangement is impractical, the cold water basin heat must beprovided in the tower itself. Electric immersion heaters, steam injectors, or steam coils, controlled by athermostat in the cold water basin, may be used. Consult your BAC Representative for details. Additionally,all exposed make-up lines and water piping that does not drain at shutdown should be traced with electricheater tape and insulated.

EASY CONNECT Piping Arrangement with BALANCE CLEAN CHAMBER (Optional Series 3000):Draining the water from the BALANCE CLEAN Chamber and internal piping is essential whenever thepotential for freezing temperatures exist. This can be accomplished by utilizing the 1/2" NPT drain portlocated on the inboard side of the BALANCE CLEAN Chamber. There are 3 recommended methods fordraining the piping:1. The preferred approach is to install a normally open 1/2" solenoid valve on the 1/2" drain connection ofthe BALANCE CLEAN Chamber. This valve should be wired in the pump circuit such that it closeswhen the pump is energized. The solenoid valve must be selected to operate with a minimum pressuredifferential of zero PSI. The zero pressure differential valve is required due to the limited static headimposed on the valve from the water column.

2. A 1/2" manual valve can be installed on the 1/2" drain connection of the BALANCE CLEAN Chamber.The valve should be opened during cold weather operation. CAUTION: The valve must be closedduring warm weather to obtain full thermal performance.

3. Remove the 1/2" plug from the 1/2" drain connection of the BALANCE CLEAN Chamber during coldweather operation. CAUTION: The plug must be reinstalled during warm weather to obtain full thermalperformance.

When operating at subfreezing ambient temperatures, the cooling tower will normally produce leaving watertemperatures appreciably below design. However, low leaving water temperatures tend to promote iceformation. Therefore, when operating in subfreezing ambient temperatures, the leaving water temperaturesshould be maintained as high as possible. The recommended minimum water temperature in the cold waterbasin is 43F (6.1C). Additionally, frequent visual inspections should be performed to detect potential icingproblems.

The first step in maintaining a high leaving water temperature is to ensure the tower operates with themaximum possible heat load. Next, reduce the tower capacity by cycling fans, which modulates the air flowthrough the tower. Modulating the water flow rate to the tower is not recommended as a method for coolingtower capacity control. (CAUTION: Rapid on-off cycling can cause the fan motor to overheat. It isrecommended that controls be set to allow a maximum of 6 on-off cycles per hour.) If the tower is equippedwith two-speed motors or VFD, operation at a lower speed may be sufficient to prevent icing.

Note: When two speed motors are used, the motor starter should include a minimum 15 second timedelay when switching from high to low speed.

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However, it may also be necessary to cycle fans off periodically to prevent ice formation and/or to melt icethat accumulates on the intake louvers and face of the fill of the Series 3000 and Series 1500 CoolingTowers. Under severe conditions where fan cycling is insufficient to prevent icing, it may be necessary tooperate the fan(s) in reverse for short periods of time to remove any ice accumulation by forcing warm airthrough the fill.

WARNING: DO NOT operate the fans in reverse any longer than is necessary since extended reverseoperation may cause ice to form on the fan blades, fan cowl, or eliminators and damage the tower.

Because of this possibility, cooling towers using reverse fan operation for ice removal should be equippedwith a vibration cutout switch and the duration of reverse operation should be limited to a maximum of 30minutes. A time delay of approximately 40 seconds between forward and reverse direction should beincorporated into the motor controls. Lastly, the importance of performing frequent visual inspections androutine maintenance services during operation in subfreezing weather cannot be overemphasized. Thesemust be carried out on a routine basis to:

1. Ensure all controls for capacity and freeze protection are set properly and functioning normally.2. Prevent excessively high water levels and possible overflow of the cold water basin due to over

pumping clogged strainers, or make-up valve malfunction.3. Discover any icing conditions that may develop before they reach the point where the tower or

supports are damaged or system performance is impaired.

For more detailed information on winter operation and for recommended operating procedures on specificinstallation, contact your local BAC Representative.

Water TreatmentA proper water treatment program, administered under the supervision of a competent water treatmentspecialist, is an essential part of routine maintenance to ensure the safe operation and longevity of evapora-tive cooling equipment, as well as other system components.

In evaporative cooling products, cooling is accomplished by evaporating a small portion of the recirculatingwater as it flows through the unit. As this water evaporates, the impurities originally present in the waterremain behind and, if not controlled, the concentration of dissolved solids will increase rapidly. This can leadto corrosion, scale or biological fouling which may negatively affect heat transfer as well as the longevity ofthe unit and other system components.

Corrosion Red rust on steel components and "white rust" on galvanized surfaces will affect thelongevity of the unit.

Scale formation Scale not only reduces heat transfer and system efficiency, but may lead to underdeposit corrosion.

Biological Fouling Slime and algae formations may reduce heat transfer, promote corrosion, andharbor pathogens such as Legionella.

Each of these aspects of water quality is discussed in greater detail below. Since the quality of the ambientair and make-up water varies significantly from job site to job site, BAC strongly recommends obtaining theservices of a competent water treatment specialist prior to the initial start-up of the evaporative coolingequipment. Additionally, to protect against the risk of Legionella contamination, the cooling equipmentshould never be operated without adequate biological control.


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Corrosion and Scale ControlTo control corrosion and scale, the water chemistry of the recirculating water must be maintained within certainparameters. The specific measures required vary from system to system and are dependent on the chemistryof the make-up water, the metallurgy of the piping and heat transfer devices exposed to the recirculatingwater, and the temperatures at which the system will be operating. Bleed/blowdown, the continuous flow of asmall portion of the recirculating water to a drain, is used to control the concentration of dissolved solids. Onrare occasions this may be adequate to control scale and corrosion. More often, however, chemical scale andcorrosion inhibitors are necessary, which raise the allowable level of dissolved solids without the risk of scaleand corrosion.

Chemically treated water should be kept within the guidelines given in Table 7. In cases where bleed/blowdown alone is being employed for corrosion and scale control, without chemical treatment, your watertreatment specialist may recommend more conservative limits than those shown in Table 7.

Table 7 Quality Guidelines for Chemically Treated CirculatingWater

Chemical treatment programs must meet the following requirements:1. The chemicals must be compatible with the unit materials of construction as well as other materials used inthe system (pipe, heat exchanger, etc.)

2. Chemical scale and corrosion inhibitors, and particularly acid (if used) should be introduced into thecirculating water through automatic feeders at a point in the system where total mixing and dilution occurbefore reaching the evaporative cooling equipment. The preferred injection point for chemical scale andcorrosion inhibitors is on the discharge side of the system circulating pump(s). These chemicals should notbe batch fed directly into the units cold water basin or water distribution system, as this can severelydamage areas directly contacted.

3. When chlorine is added to the system, free residual chlorine should not exceed 1 ppm, except as noted instart-up and shut-down section. Exceeding this limit may accelerate corrosion.

*PassivationWhen new systems are first commissioned, special measures should be taken to ensure that galvanized steelsurfaces are properly passivated to provide maximum protection from corrosion. Passivation is the formation of aprotective, passive, carbonate layer on galvanized steel surfaces. To ensure the galvanized steel surfaces arepassivated, the pH of circulating water should be kept between 7.0 and 8.2 for four to eight weeks after start-up,or until new zinc surfaces turn dull gray in color. If white deposits form on galvanized steel surfaces after the pHis returned to normal service levels, it may be necessary to repeat the passivation process.

NOTE: Stainless steel units and units protected by the BALTIBOND Corrosion Protection System do notrequire passivation.

Property of Water Recommended Level

pH 6.5 to 9.0*

Hardness as CaCO3 30 to 750 ppm2

Alkalinity as CaCO3 500 ppm maximum2

Total Dissolved Solids 1500 ppm maximum

Conductivity 2400 micromhos3

Chlorides250 ppm maximum as Cl

410 ppm maximum as NaCl

Sulfates 250 ppm maximum

Silica 150 ppm maximum

Opera

tingandMainten

ance

Manuals

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Biological ControlThe warm, oxygen and nutrient rich environment inside evaporative cooling equipment provides an idealenvironment conducive to the growth of algae, slime, and other micro-organisms. Uncontrolled, this canreduce heat transfer, promote corrosion, and promote the growth of potentially harmful organisms such asLegionella. To avoid biological contamination and minimize the risk of Legionella, initiate the biocidetreatment program at start-up and continue on a regular basis thereafter in accordance with the treatmentsuppliers instructions. Bleed/blowdown or chemical treatment used for corrosion and scale control alone isnot adequate for control of biological contamination.

Solid or granular biocides should be introduced through a chemical "pot" feeder installed in parallel with thesystem circulating pump(s). Dilute liquid biocides may be added directly to the cold water basin. If ozonewater treatment is used, at no point should concentrations exceed 0.5 ppm.

Start-up, Initial and Following a Shutdown PeriodTo minimize the risk of biological contamination during a shut-down period of three days or more, it isrecommended that the entire system (evaporative cooling equipment, system piping, heat exchangers, etc.)be drained. To resume operation of a drained system and at initial start-up, clean all debris from the coldwater basin and fill the system with fresh water. Then execute one of the following biocide treatmentprograms while operating the circulating pump(s) and prior to operating the unit fans:

1. Resume treatment with the biocide that was used prior to shut-down. Then run the pump only whilemaintaining the maximum recommended biocide residual for a sufficient period of time (residual and timewill vary with the biocide) as recommended by the water treatment supplier. Only after this treatmentperiod is completed should the fan(s) be started.

2. Check the pH of the circulating water and, if necessary, adjust it to 7.0 to 7.6. Then, running the pumponly, treat the system with sodium hypochlorite to maintain a level of 4 to 5 mg/l (ppm) free chlorine(as Cl2) over a six (6) hour period. Test kits that can be used to measure the free residual of chlorine arecommercially available. Only after this treatment period is completed should the fan(s) be started

.

When it is not practical to drain the system during shut-down periods, a by-pass line with shut-off valvesshould be installed to permit the recirculating water to be circulated throughout the system, including the unitbasin, while bypassing the fill section of the evaporative cooling equipment (fans should remain off). Thesystem should be treated per one of the two methods described above prior to restarting the unit.

01.BAC HBii Maintenance of Crossflow Towers

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