Pfs Differential Flow Meter Bulletin

7/28/2019 Pfs Differential Flow Meter Bulletin

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DOCUMENT NUMBER: 2005-100

2006 Primary Flow Signal, Inc. All Rights Reserved

Primary Flow Signal, Inc.- WORLD HEADQUARTERS800 Wellington Avenue Cranston, RI 02910, USA http://www.primaryflowsignal.com

toll free: 1-877-737-3569 phone: 401-461-6366 fax: 401-461-4450

DIFFERENT IAL FLOW

METER SELECT ION GUIDEPRODUCT BULLETI

Purpose:

Format:

The purpose of this guide is to provide an objective method of selecting the type of differential flow meter that best suits a particularapplication. The comparative information presented is based on 25 years of field experience as well as a wide range of technicalpapers and codes which offer valuable guidance and insight into the performance and characteristics of differential devices.

Each section focuses on a particular flow meter type. Within the section, key characteristics and performance attributes areenumerated. Notes are provided for each section that further elaborate and qualify certain statements, and should be consideredintegral to the presentation and to any conclusions the reader makes with respect to the flow meters considered.

ORIFICE NoLimit

50 to 70percent

+/- 0.50 to+/-1.50**

+/-0.67 ***

Must begreater than

10,000

App roach andDownstream

Required

0.20 through0.75

Acc uracy isadversely affected

by any changein bore edge****

Non-abrasive, clearlow viscosity liquid

or gas

LOW

*Per ASME Fluid Meters;**Depending on bore size (smaller bo res 70%, larger bo res less than 70%);***If in compliance with AGA 3 r equirements;****The accuracy of an orifice plate is in fluenced by any change to the sharpness of its bore edge. This demands regular fieldinspection and replacement if change is noted. Approach and discharge straight piping must comply wit h ASME Fluid Meterrequirements, including need for flow straighteners, if indicated;

MeterType

Line SizeRange

(inches)

Headloss% of

Differential

BasicAcc uracy(% of Total)

Minimumpipe Reynolds

number

RequiredStraightPiping

BetaRange

UsefulService

Life

ServiceFunctional

Limits

CostRange

ORIFICE NoLimit

50 to 70percent

+/- 0.50 to+/-1.50**

+/-0.67 ***

Must begreater than

10,000

App roach andDownstream

Required

0.20 through0.75




or gas

LOW

*Per ASME Fluid Meters;**Depending on bore size (smaller bores 70%, larger bores less than70%);***If in compliance with AGA 3 requirements;****The accuracy of an orifice plate is influenced by any change to thesharpness of its bore edge. This demands regular field inspection andreplacement if change is not ed. Approach and disc harge straight pipingmust co mply with A SME Fluid Meter requirements, including need for flowstraighteners, if indicated;

MeterType

Line SizeRange

(inches)

Headloss% of

Differential



number


BetaRange

UsefulService

Life

ServiceFunctional

Limits

CostRange

WEDGEPFS Wedge-

typeTM

WEDGEPFS Wedge-

typeTM

thru

24.0 *

thru

24.0 *

30 to 60percent

30 to 60percent

+/- 2.0 to+/-4.0**

+/- 2.0 to+/-4.0**

Must begreater than

500

Must begreater than

500

Approac h andDownstream

Required


Required

0.20 through0.5 H/D***


Long

Long

Ideal for harsh,high viscosity,liquid, slurry or

gas service


gas service

LOW****

LOW****

*Larger line sizes are available but must be laboratory flow calibrated.**Accuracy stated is standard, non-laboratory flo w calibrated value. Accuracy of +/- 0.50% is possible with laboratory flowcalibration (must include up and down stream piping.)***H/D is the ratio between wedge segment opening (H) and the inside diameter of the meter body (D).****The relative capital cost of dif ferential produci ng flo w meters c an vary. Selection criteria recommending the Wedge metermust emphasize its superior ability to m easure harsh, abrasive, high viscosity, and otherwise difficult service conditions.

*Larger line sizes are available but must be laboratory flow calibrated.**Accuracy stated is standard, non-laboratory flow calibrated value. Accuracy o f +/- 0.50% is possible w ithlaboratory flow calibration (must include up and down st ream piping.)***H/D is the ratio between wedge segment opening (H) and the inside diameter of the meter body (D).****The relative capital cost of differential producing flow m eters can vary. Selection crit eria recommending theWedge meter must emphasize its sup erior ability to measure harsh, abrasive, high visc osity, and otherwisedifficult service conditions.

WEDGEPFS Wedge-

typeTM

ELBOW

thru

24.0 *

1.0to any

line size

30 to 60percent

N/A*

+/- 2.0 to+/-4.0**

+/- 4.0 **

Must begreater than

500

Must begreater than

10,000


Required

Approac h(Upstream)Required


N/A

Long

Long


gas service

Clear liqu idand gas.

LOW****

VERYLOW

*Larger line sizes are available but must be laboratory flow calibrated.** Accuracy stated is standard, non-laboratory flow calibrated value. Accuracy of +/- 0.50% is possible wi th laboratory flow calibration (must includeup and down stream piping.)*** H/D is the ratio between wedge segment opening (H) and the inside diameter of the meter body (D).**** The relative capital c ost of differential producing flow meters can vary. Selection criteria recommending the Wedge meter must emphasize itssuperior ability to m easure harsh, abrasive, high vis cosity, and otherwise difficu lt service conditions .

* The Elbow meter utilizes the headloss created by flowpassing throug h the elbow as a differential pressure signal.This limits th e elbow meter application to flow rate range(s)that can accurately be covered by the secondary instrument(DP transmitter) particularly as regards the low enddifferential pressure. Typically an Elbow m eter useful rangeis 3 or 4 to 1 on flow.

** Per ASME. Better accuracy ca with speciall y machinedelbows and laboratory flow calibration. Repeatability is goodat 0.2% or better.


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DIFFERENT IAL FLOW


ORIFICE

WEDGEPFS Wedge-

typeTM

NoLimit

thru

24.0 *

50 to 70percent

30 to 60percent

+/- 0.50 to+/-1.50**

+/-0.67 ***

+/- 2.0 to+/-4.0**

Must begreater than

10,000

Must begreater than

500

Approach andDownstream

Required


Required

0.20 through0.75




Long Ideal for harsh,high viscosity,liquid, slurry or

gas service

LOW

LOW****

*Per ASME Fluid Meters;**Depending on bore size (smaller bor es 70%, larger bor es less than 70%);***If in compliance with AGA 3 requirements;****The accuracy of an orifice plate is inf luenced by any c hange to the sharpness of its bore edge. This demands regular fieldinspection and replacement if change is noted. Approach and discharge straight pipi ng must comply w ith ASME Fluid Meterrequirements, including need for flow straighteners, if indicated;

*Larger line sizes are available but must be laboratory flow calibrated.**Accuracy stated is standard, non-laboratory flo w calibrated value. Accuracy of +/- 0.50% is possib le with laboratory flowcalibration (must include up and do wn stream piping.)***H/D is the ratio between wedge segment opening (H) and the inside diameter of the meter body (D).

****The relative capital cos t of differential producing flow meters c an vary. Selection criteria recommending th e Wedge metermust emphasize its superior ability to measure harsh, abrasive, high viscosity, and otherwise difficult service cond itions.

Line SizeRange

(inches)

Headloss% of

Differential



number


BetaRange

UsefulService

Life

CostRange

FLOWNOZZLE

CLASSICALVENTURI

Greaterthan2.0

4.0thru

48.0 *

40 to 95percent*

12 to 30percent**

+/- 0.25 to+/-2.00**

+/-1.0 to+/-2.0

Must begreater than

10,000

Must begreater than

100,000

Approach andDownstreamRequired***

Approach on lyRequired

0.20 through0.80***

0.40 through0.80

Medium tolong

Medium***Periodic Tap andannular chambermaintenance i s

required.

Clear liqu ids,gas and steam

MED.to

HIGH

HIGH

*Per ASME, ISO 5167 and MFC-3M-85.** Headloss is a function of Beta ratio; the smaller the Beta thehigher the headloss.*** ASME Classical Venturi meters, by des ign, have annularchambers, and all prior test data referring to these designsincludes the performance effects of t hese chambers. Since theannular chambers are subject to plu gging in contaminatedprocess fluid applications, clear liquids and gases present thebest use of this meter design. Because corrosion may produ ceplugging effects to the annular chamber and impulse taps overtime, as well, useful service life is co ntingent upon material

selection. Periodic maintenance work to remove detritus andplugging is recommended.

Line SizeRange

(inches)

Headloss% of

Differential



number


BetaRange

UsefulService

Life

CostRange

ServiceFunctional

Limits

Clear Liquids, Gasand steam****

ServiceFunctional

Limits

*Headloss is a function o f bore size. If nozzle is part of a meter run in cluding straightening vane(asrequired by some codes) loop headloss will b e on high side.**Per ASME includin g ASME PTC-6.***Consult ASME and ISA for specific design requirements as function of Beta ratio.****One prominent use of the ASME Nozzle and ASME Nozzle meter run is for steam turbine efficiencytesting as specified by ASME PTC-6.

that a number o f international codes govern use and design of flow nozzles, ASME, ISA andothers. While they cover similar meter embodiments, design parameters and , andstated performance in key areas may differ.

Noterequirements

MeterTypeMeterType

(Continued)(C)2005-Primary Flow Sig nal, Inc.-All right s reserved.

This 24.0 ClassicalVenturi is beingrefurbished in PFSWarwick, RI facility.Only the entrancevestibule and throatsection are shown. Thecomplete flow meter isnearly twice the length

WEDGEPFS Wedge-

typeTM

thru

24.0 *

30 to 60percent

+/- 2.0 to+/-4.0**

Must begreater than

500


Required


Long Ideal for harsh,high viscosity,liquid, slurry or

gas service

LOW****

*Larger line sizes are available but must b e laboratory flow calibrated.**Accuracy stated is standard, non-laboratory f low calibrated value. Accuracy of +/- 0.50% is p ossible with laboratory flowcalibration (must include up and do wn stream piping.)***H/D is the ratio between wedge segment opening (H) and the inside diameter of the meter body (D).****The relative capital cos t of differential producing flow meters c an vary. Selection criteria recommending th e Wedge metermust emphasize its superior ability to measure harsh, abrasive, high viscosity, and otherwise difficult service cond itions.

MODIFIEDSHORTFORM

VENTURI

0.50to any

line size

3.50 to10.0

+/- 0.50 * Must begreater than

75,000

App roach(Upstream)Required

0.20 through0.80

Very Long Clear liquid,gas, steam, andcontaminatedline fluid(s).**

MED.

* Modified short form Venturi meters can be madeof any machinable material and in any lin e size. Thebasic accuracy is substantiated by prior laboratoryflow calibrations and there is no effect onperformance as a function o f line size or Beta ratio.+/-0.25% accuracy (or better) is achievable through

individual laboratory flow calibration.

** Modified Short Form Venturi meters can beequipped with sealed diaphragm sensors toeliminate plugging con cerns by suspended solidsin process fluid. Options are available for i n-placecalibration of secondary instrumentation withoutnecessity for line shut-down o r equipment removal.


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DIFFERENT IAL FLOW


ORIFICE

WEDGEPFS Wedge-

typeTM

NoLimit

thru

24.0*

50 to 70percent

30 to 60percent

+/- 0.50 to+/-1.50**

+/-0.67 ***

+/- 2.0 to+/-4.0**

Must begreater than

10,000

Must begreater than

500

Appro ach andDownstream

Required

Appro ach andDownstream

Required

0.20 through0.75


Acc urac y i sadversely affected

by any changein b ore edge****

Long


or gas


gas service

LOW

LOW****

*Per ASME Fluid Meters;**Depending on bore size (smaller bores 70%, larger bores l ess than 70%);***If in co mpliance with AGA 3 requi rements;****The accuracy of an orif ice plate is influ enced by any change to the sharpness of its bore edge. Thisdemands regular field inspecti on and replacement if change is noted. Approach and discharge straightpiping m ust comply wi th ASME Fluid Meter requirements, including need for flow st raighteners, if indicated;

*Larger line sizes are available but must be laboratory flo w calibrated.**Accuracy stated is standard, non-laboratory flo w calibrated value. Accuracy of +/- 0.50% is possib le withlaboratory flow calibration (must include up and down stream piping.)***H/D is the ratio between wedge segment opening (H) and the ins ide diameter of the meter body (D).****The relative capital cost of differential produ cing fl ow meters can vary. Selection crit eria recommendingthe Wedge meter must em phasize its superior abil ity to measure harsh, abrasive, high viscosit y, andotherwise difficult service conditions.

MeterType

Line SizeRange

(inches)

Headloss% of

Differential

BasicAccur acy(% of Total)


number


BetaRange

UsefulService

Life

ServiceFunctional

Limits

CostRange

HBX-1

HBX-2ELBOW

0.50to any

line size

0.25t0 any

line size

18 to 25percent

Standardelbow

+/- 0.50*

+/- 2.0*

Must begreater than

6,600

Must begreater than

5,000

Appro ach o nlyRequired

Very sh ortAppro ach

onlyRequired

0.20 through0.80

Any**

Very Long

Very Long

Clear liquids, gasesand steam.

Ideal for l iquid,gas, steam andcontaminated

service

LOW

VERYLOW

*The PFS-X1 was designed to pro vide Venturi meter accuracy, repeatability and l ong service l ife butincludi ng low fl ow rate capability (down t o 6,600 pipe Reynolds number) which cannot be easily achievedusing st andard Venturi meter designs.

**The significant beneficial feature of t he PFS-X1 is that it is not limi ted to 75,000 pipe Reynolds numberlow limi t for const ant accuracy as is the case for the Modified Short Form Venturi desi gn. This results in asignificantly lower flow range-ability of this design while still enjoying high, stable and linear accuracyperformance envelope.

*Laboratory flow c alibration wi ll impro ve meter accuracy to +/-0.25%.

** Reduced bore is specifically designed to develop high diff erentials.NOTE: a variety of tap orientations are utilized depending on the type of service int ended.

MeterType

Line SizeRange

(inches)

Headloss% of

Differential

BasicAccur acy(% of Total)


number


BetaRange

UsefulService

Life

ServiceFunctional

Limits

CostRange

(Continued) (C)2005-Primary Flow Signal, Inc.-All righ ts r eserved

PFS Self Checking Option-Short form Venturi and HBX-1 meters can beequipped with a self checking system that comparestwo independent pressure sources and alarms if thechange exceeds a range limit. The alarm then signalseither a transmitter malfunction or unacceptablechange to the internal geometry of the flow meterrequiring maintenance or corrective action. Thisprevents long term undetected accuracy degradationin critical applications. 64:1applications, and triple

ABRASIVE LINE

FLUID NOT APROBLEM!Novel rectangularVenturi design byPrimary Flow Signal,Inc.

Features removableand replaceablesegment for harsh andabrasive service

PFSFlowMaster-fully integrated secondary metering system

Primary Flow Signal, Inc. Has developed a wide variety of secondary instrumentationmetering systems which can be used with a broad range of differential producer typeflow meter primaries. The selection of equipment that is factory installed, tested andcalibrated is dependent upon the specificrequirements of each application. Single range systems are most frequently used for8:1 flow range applications. Dual range systems are used on 64:1applications, andtriple range systems can be effectively used up to 500:1 applications.

inside a properly sized NEMA 4X enclosure,


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DIFFERENT IAL FLOW


Pfs Differential Flow Meter Bulletin

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