Flowmeter Selection and Sizing

-NIDHIN MANOHAR

What is a Flow meter?

An ideal flow meter is a group of linked components that will deliver a signal uniquely related to the flow rate or quantity of fluid flowing in a conduit, despite the influence of installation and operating environment.

Flowmeter used for

Indication

Quantification ( Estimation & Planning)

Custody Transfer (Billing)

Control ( Demand )

Alarm

Desirable Features of FlowmeterDesirable Features of Flowmeter● Be of intrinsically high accuracy

● Maintain its accuracy under a wide range of liquid conditions

● Have high flow detection sensitivity, even at zero flow

● Have high flow range ability, including reverse flow capacity

● Be of high reliability, requiring little or no maintenance

● Install easily without altering pipe line operating conditions

● Be of low installed cost, as compared to Turbine or PD meters

● Not be subject to wear, or change of calibration through use

● Be of fast response, to detect catastrophic leaks in seconds

● Be capable of monitoring large lengths of pipeline

● Be rugged relative to actual site environmental conditions

● Perform accurately in Multi-product pipelines

● Be capable of detecting and compensating for free gas

● Detect Empty pipe conditions instantly

● Not be affected by corrosive or abrasive liquids

● Produce minimum to zero pressure drop

● Be compatible with many different types of nondescript liquids

● Be capable of installation near bends and elbows

● Require only minimal operating power, for remote area operation

Desirable Features of FlowmeterDesirable Features of Flowmeter

● More Information about the process, including pressure and temperature.

● Flowmeters that are easier to calibrate

● Self calibrating flowmeters or flowmeters that can be calibrated with a software package

● Better diagnostics

● A predictive maintenance light

A typical Process Flow Diagram showing Overall Measurement Uncertainties expected in a Fiscal Quality measurement

Prescribed Levels of Metering Accuracy for Petroleum FluidsHydrocarbon

LiquidHydrocarbon

GasFiscal or Custody transfer Quality

measurement0.25% 1%

Field or Platform allocation 1% 3%Well allocation 5% 5%

Liquid GasFiscal Quality 0.25 1

Near Fiscal Quality 0.25 - 1.0 1.0 - 2.0Fiscal Allocation 0.5 - 5 2 - 5Fiscal Well Test

Fiscal Multiphase Metering

Typical Uncertainty in Mass Flow rate measurement (%)Measurement Approach

1010 - 20

Canada Offshore Petroleum Board Measurement Guidelines – Oct 2003

DTI Measurement Guidelines – December 2003

SELECTION OF FLOWMETERS

• Selection of a flow meter as per the requirement sometimes poses a challenge to instrumentation engineers and consultants because of

i) varying requirements of the installation

ii) availability of large no. of instruments in the market

iii) absence of comparative data

Here a general approach is considered

• FLOWMETER CLASSIFICATION :- Different classification of flowmeters

Additive / Extractive Invasive / Non InvasiveInsertion / Clamp-onMass flow / Volume flow / Point velocity

-Based on the technology employed in metering, about 50 different types of flow metering devices can be identified.

-These are usually Classified into 9 or 10 groups

Group Description1 Orifices, Venturi's and Nozzles2 Other differential pressure types

3 Positive displacement types4 Rotary turbine types5 Fluid oscillatory types6 Electromagnetic types7 Ultrasonic types8 Direct and indirect mass types9 Thermal types10 Miscellaneous types

FLOWMETER SELECTION

Preliminary selection is based on the application to which the meter is to be put. Table below shows the check list for the suitability of various flowmeters against different applications

Group Type A B C D E F G H J K L M N P Q R S TOrifice ? ? ? ? ? ?Venturi ? ? ? ? ? ? ?Nozzle ? ? ? ? ? ?VA + ? ?Target + ? ?Averaging Pitot ? ? ? ?Sonic nozzle ? ?Sliding vane + ?Oval gear + + ?Rotary piston ? + ? +Gas diaphragmRotary gasTurbine + ? ? ? +Pelton ? ? ? ?Mechanical meter + ?Insertion turbine ? ? ?Vortex ? ?SwirlmeterInsertion vortex ? ? ? ? ? ?Electromagnetic + ? ?Insertion electromagnetic ? ? ?Doppler ? ? + ? ? ?Transit time ? + ? + + ? ? + +Coriolis (direct) + ? ? ? +Twin rotor (indirect)Anemometer ? ? +Thermal mass +Tracer + + + ? +Laser ? ?

Keyis suitable; generally applicable

? is worth considering; sometimes applicable+ is worth considering;limited availability or tends to be expensive A blank indicates unsuitable; not applicableNOTE 1. Liquid applications are indicated by the following NOTE 2. Gas applications are indicated by the following : A General liquid applications (<50cP (<0.05OPa.s) J General gas applications B Low liquid flows (<0.12m3/H)(<2 L /min) K Low gas flows (<150 m3/h) C Large liquid flows (>1000m3/h)(>1.7x10 L/min) L Large gas flows (>5000 m3/h) D Large water pipes (>0.5m bore) M Hot gases (temperatures <200 deg.C) E Hot liquids (temperatures >200 deg.C) N Steam F Viscous liquids (>50 cP) (>0.05 Pa.s) Note 3. Miscellaneous applications are indicated by the following G Cryogenic liquids P Slurries and particle flows H Hygienic liquids Q Liquid liquid mixtures

R Liquid gas mixturesS Corrosive liquidsT Corrosive gases

Table 2.1 Broad areas of application

2

3

10

9

8

7

6

5

4

1

ApplicationLiquids (see note 1) Gases (see note 2) Miscellaneous (see note 3)

SELECTION PARAMETERS

• Performance considerations

• Fluid property considerations

• Installation considerations

• Environment considerations

• Economic factors

Table 2.2 Selection procedure variables1 Performance

considerationsAccuracy Repeatability Linearity Rangeability Pressure drop Output signal characteristics Response time Uncertainty Orientation Flow direction Upstream and downstream pipework Line size Location for servicing Effect of local vibration Provision of accessories like filters, straighteners, transducers etc. Hazardous atmosphere Effect of pulsations/unsteady flow

2 Fluid property considerations

Liquid or gas Temperature Pressure Density Specific gravity Viscosity Lubricity Presence of other components Chemical properties Surface tension Compressibility Real gas effects Abrasiveness Presence of other phases

3 Installation considerations

Orientation Flow direction Upstream and downstream pipework Line size Line size Location for servicing Effect of local vibration Provision of accessories like filters, straighteners, transducers etc. Hazardous atmosphere Effect of pulsations/unsteady flow

4 Environments considerations

Ambient temperature effects Humidity effects Safety factors Pressure effects Electrical interference

5 Economic Purchase price Installation costs Operation costs Pumping power and headloss Technical optmization Meter life Spares cost and availability Maintenance costs Calibration costs

Performance considerationsAccuracy : is the closeness to truth. considering application of flowmeter, eg.

Custody transfer very high accuracy is required. Should be careful about method of specifying errors by the vendors ie., whether % of Full scale Or % of reading

Repeatability : is the ability of a meter to reproduce a

measurement each time a set of conditions are reproduced and is expressed as the allowable percentage deviation from the stated value under a given set of conditions.

Is a measure of the stability of the meter

Good Accuracy

Good Repeatability Bad Accuracy

Rangeability : is the ratio of the maximum to minimum flowrates for a given performance. A judicious choice is needed for the application since rangeability differs with the meter selected. eg. Orifice plate - 3:1 to 4:1 Thermal mass flow meter/PD 100:1 to 500:1

Pressure drop at maximum flow:The pressure drop caused by the meter is important since it may affect process efficiency. In liquid applications extreme pressure drops can lead to cavitation and consequent faulty metering

Output signal characteristics :Normally a flow meter may directly or indirectly measure

Volume rate of flow Mass flow rateTotalized flow Mean flow capacityPoint velocity

These output may be in voltage, current or pulses which may have to be interfaced with flow computers, data loggers, alarm systems etc. The particular instrument selected should be compatible to these.

Group – 1

Group – 2

Group – 3

Group – 4

Group – 5

Group – 6

Group – 7

Group – 8

Group – 9

Group – 10 0.03 0.1 0.3 1.0 3.0 10 30

Uncertainty % Flow rate Typical Performance Distribution of Flow meter Groups

Group Type Linearity (%) Repeatibility (%)Rangeability X

: 1 where X

Pressure drop at

maximum flow

Flow parameter

Response time

1Orifice Venturi Nozzle

# # #

# # #

3 or 4 3 or 4 3 or 4

3-4 2

2-3

R R R

# # #

2

Variable area Target

Averaging Pitot Sonic nozzle

+/-1%FS to +/-5% FS NS #

+/-0.25%

+/-1%FS to +/-5% FS NS #

+/-0.25% R

10 3 #

100 : 1

3 3

1-2 3-4

R R

Vm R

No data NS #

NS

3

Sliding vane Oval gear

Rotary piston Gas diaphragm

Rotary gas

+/-0.1R to +/-0.3%R +/-0.25%R

+/-0.5R to +/-0.2%R No data +/-1%

+/-0.01%R to +/-0.05% R +/-0.05%R to +/-0.1% R

+/-0.2% R No data +/-0.2%

10 to 20 -

10 to 250 100 25

4-5 4

4-5 2 2

T T T T T

> 0.5 ms < 0.5 ms > 0.5 ms > 0.5 ms < 0.5 ms

4

Turbine Pelton

Mechanical meter Insertion turbine

+/-0.15 R to +/-1% R +/-.25R to +/-0.2% R

No data +/-.25 R to +/- 5% R

+/-0.02%R to +/-0.5% R +/-0.1%R to +/-0.25% R

+/-1% FS +/-0.1% R

5 or 10 4 or 10

10 or 280 10 to 40

3 4 3

1-2

R R R

Vp

5ms to 25 ms 5ms to 25 ms

50 ms 5ms to 25 ms

5Vortex

Swirlmeter Insertion vortex

+/- 1 % R <+/-2% R

+/-2%

+/-0.1%R to +/-1% R NS

+/-0.1% R

4 or 40 10 or 30 15 or 30

3 3 1

R R

Vp

0.5s minimum NS 5ms

6Electromagnetic

Insertion Electromagnetic

+/-0.5%R to +/-1% R +/-2.5%R to +/-4% R

+/-0.1% R to +/-0.2%FS +/- 0.1%R

10 to 100 10

1 1

R Vp

> 0.2 s NS

7Doppler

Transit timeNo data

+/-0.1R to +/-1% R+/-0.2% FS

+/- 0.2%R to +/-1%FS5 to 25

10 to 3001 1

Vm R

0.1s to 120s

8Coriolis Twin

rotorNS

No data+/-0.1%R to +/-0.25% R

No data10 to 100 10 to 20

2-5 3-4

R R

0.1s to 3600s 50ms

9Anemometer

Thermal massNo data

+/-0.5R to +/-2% R+/-0.2% FS

+/-0.2%FS to +/-1% R10 to 40

10 to 5002 2

Vp R

No data 0.12 to 7 s

10 Tracer LaserNo data No data

No data +/-0.5% R

Upto 1000:1 Upto 2500:1

1 1

Vm Vp

No data No data

Performance Factors in meter selection

Fluid Property ConsiderationsFluid Property Considerations

Fluid Temperature & Pressure/Vacuum Provision for CompensationMaterials should stand the temp/pressure/vacuum

Fluid Density and Specific GravityProvide for compensation (on line) ?

ViscosityGases effect is smallRangeability and performance affected

Chemical PropertiesCompatibility of materials

Compressibility

Single Phase/Multi-phase Fluid

Group Type

Orifice 400 <+650 3 x 104 L,G P

Venturi 400 <+650 1 x 105 L,G P

Nozzle 400 <+650 2 x 104 L,G NVA 700 -80 to 400 No data L,G N

Target 100 -40 to 120 3 x 104 L,G S

Averaging Pitot 400 <+540 1 x 104 L,G N

Sonic nozzle 400 <+650 2.5 x 104 G N

Sliding vane 100 -30 to +200 1 x 103 L N

Oval gear 100 -15 to + 290 1 x 102 L N

Rotary piston 170 -40 to +170 1 x 102 L N

Gas diaphragm 200 -30 to +200 2.5 x 102 G N

Rotary gas 100 -40 to +150 1 x 103 G NTurbine 3500 -268 to +530 L,G

Pelton 600 -225 to 530 1 x 104 L,G NMechanical meter 70 -25 to +200 L,G NInsertion turbine 250 -50 to +430 L,G N

Vortex 260 -200 to + 430 2 x 104 L,G PSwirlmeter 100 -40 to +110 No data L,G N

Insertion vortex 70 -30 to +150 5 x 103 L,G NElectromagnetic 300 -60 to +220 No limit L S/PInsertion electromagnetic 20 +5 to +25 No data L N

Doppler * -20 to +80 5 x 103 L S

Transit time 200 -200 to +250 5 x 103 L,G N/P

Coriolis 390 -240 to 400 1 x 102 L P

Twin rotor 400 -240 to 350 1 x 104 L NAnemometer 20 -200 to 400 No data L,G NThermal mass 300 0 to 100 No data L,G NTracer No data No data No limit L,G PLaser No data No data No limit L,G N

Key S is suitable P is possible N is not suitable * is dependent on the rating of the pipe wall

Gas (G) or Liquid (L)

Two or more

1

Maximum pressure

Temperature range

Minimum ReD

Table 2.4 Selection by fluid property constraints

2

3

10

9

8

7

6

5

4

The Effect of Pressure Deviations on a Variable-Area Flowmeter

{PRIVATE}Maximum flowrate, L/min

Fluid temperature, °F Outlet pressure, psi Fluid type: Air 2.23 70 0 1.65 70 15 1.30 70 35 2.26 90 0 2.28 110 0 2.32 150 0 Fluid type: water 4.82 70 0 4.82 70 15 4.82 70 35 4.86 90 0 4.89 110 0 4.95 150 0

As Table shows, the effect of pressure deviations can be quite significant. This table was created using data from a variable-area flowmeter that was calibrated for air at 70°F and with the outlet of the flowmeter vented to the open atmosphere (i.e. , 0 psi of outlet pressure).

Pipe work OrientationFlow Direction

Will the meter work only in one direction ?Chances or reverse flow check valve ?Bi-directional meters to be calibrated in two directions

Upstream/Downstream Pipe WorksOrientationStraight Length

Line SizesAvailability of meters of various bore sizes

Local VibrationProvide pipe supports ?Provide pulsation (fluid) dampers ?

Location of ValvesProvide valves downstream of meterProvide upstream (full bore) and downstream valves for isolation of meter – provide

bypass line.

Electrical connections – EMI/RFI EliminationHazardous atmospherePulsations in Flow

Fast response instrumentation needed ?

Installation Considerations

mmOrifice H,VU,VD,I U,B 5D/80D 2D/8D N 6 to 2600Venturi H,VU,VD,I U 0.5D/29.5D 4D N >6Nozzle H,VU,VD,I U 5D/80D 2D/8DVA VU U 0D 0D P 2 to 600Target H,VU,VD,I U 6D/20D 3.5D/4.5D N 12 to 100Averaging Pitot H,VU,VD,I U,B 2D/25D 2D/4D P >25Sonic nozzle H,VU,VD,I U >5D >0D N >=5Sliding vane H,VU,VD,I U 0D 0D L NOval gear H U 0D 0D L NRotary piston H,VU,VD,I U 0D 0D L NGas diaphragm H U 0D 0D G NRotary gas H,VU,VD,I U,B 0D/10D 0D/5D G NTurbine H,VU,VD,I U,B 5D/20D 3D/10D P 5 to 600Pelton H,VU,VD,I U 5D 5D R 4 to 20Mechanical meter H,VU,VD,I U 3D/10D 1D/5D R 12 to 1800Insertion turbine H,VU,VD,I U,B 10D/80D 5D/10D L,G >75Vortex H,VU,VD,I U 1D/40D 5D N 12 to 200Swirlmeter H,VU,VD,I U 3D 1D N 12 to 400Insertion vortex H,VU,VD,I U 20D 5D N >200Electromagnetic H,VU,VD,I U,B 0D/10D 0D/5D N 2 to 3000Insertion electromagnetic H,VU,VD,I U,B 25D 5D N >100Doppler H,VU,VD,I U,B 10D 5D L STransit time H,VU,VD,I U,B 0D/50D 2D/5D L,G N/PCoriolis H,VU,VD,I U 0D 0D L PTwin rotor H,VU,VD,I U 20D 5D L NAnemometer H,VU,VD,I U,B 10D/40D No data L,G NThermal mass H,VU,VD,I U No data L,G NTracer H,VU,VD,I U,B + + N UnlimitedLaser H,VU,VD,I U,B 0D 0D P

Key H is horizontal flow U is uni-directional flow VU is upward vertical flow B is bi-directional flow VD is downward vertical flow R is rcommended I is inclined flow N is not necessary

+ is mixng length P is possible

Table 2.5 Selection by installation constraints

2

3

10

9

8

7

6

5

4

Quoted range of d/s lengths

FilterPipe bore

range

1

Orientation DirectionQuoted range of

u/s lengthsGroup Type

Group – 1

Group – 2

Group – 3

Group – 4

Group – 5

Group – 6

Group – 7

Group – 8

Group – 9

Group – 10

GasLiquid

Bypass

Types

Insertion

Types

Insertion

Types

1 10 100 1000 10000 Line size, mm

Note:- The shaded areas represent the overlapping range of insertion and full bore meters. Size distribution of flowmeter group

• Environments considerations

Ambient temperature effects

Humidity effects

Enhances corrosion

Powers Electrical Insulation Efficiency

Safety factors

Pressure effects

Electrical interference

Orifice 4 + + 1/2Venturi 3 + + 1/2Nozzle 3 + + 1/2VA 3 A A 1Target 3 NA A 3Averaging Pitot 3 + + 2Sonic nozzle 3 A NA 1/2Sliding vane 4 A A 1/3Oval gear 4 A A 1/3Rotary piston 4 A A 1/3Gas diaphragm 4 A NA 1/3Rotary gas 4 A NA 1/3Turbine 3 A A 4Pelton 3 A A 3Mechanical meter 3 A A 3Insertion turbine 3 A A 3Vortex 2 A A 4Swirlmeter 2 A A 3Insertion vortex 1 A N 3Electromagnetic 1 A A 3Insertion electromagnetic 1 A N 3Doppler 3/4 A A 4Transit time 3/4 NA A 4Coriolis 1 A A/NA 4Twin rotor 2 No data No data 4Anemometer 3 NA NA 2Thermal mass 4 A A 2Tracer 1 N N 1Laser 1 NA NA 4

Key N is not necessary A is available NA is not available + is dependent on differential pressure measurement

Table 2.6 Selection by environmental constraints

Group

1

2

3

4

5

6

7

1) 1is low 5 is high

Temperatu

re effect 1)Intinsically safe

versionWater and

explosion proof EMI or RFI

effect 1)

8

9

10

Type

Economic ConsiderationsPurchase priceInstallation costsOperation costs

Head loss (Pumping cost)Meter life

Spares cost and availabilityMaintenance costsCalibration costs

Calibration

• All flowmeters require an initial calibration.

• Need to recalibrate depends to a great extent on how well the meter fits the application.

Orifice 2/4 1 3 2 1Venturi 4 1/4 2 3 3Nozzle 3 3 2 3 2VA 1/3 2 2 1 1Target 3 3 2 3 3Averaging Pitot 2 3 2 2 2Sonic nozzle 2 1 3/4 2 5Sliding vane 3 5 4 4 5Oval gear 3 4 4 4 5Rotary piston 3 3 3 3 4Gas diaphragm 3 3 1 2 2Rotary gas 3 4 3 3 3Turbine 3 4 3 4 4Pelton 4 3 2 4 3Mechanical meter 3 2 2 3 3Insertion turbine 2 3 A 2 3Vortex 3 3 3 3 3Swirlmeter 3 4 3 3 3Insertion vortex 2 3 2 3 3Electromagnetic 3 3 1 3 3Insertion electromagnetic 2 3 2 3 2Doppler 1/3 1 1 3 2Transit time 1/4 3 1 3 2Coriolis 3 4 4 3 3Twin rotor 3 3 3 3 3Anemometer 3 2 1 3 3Thermal mass 3 4 2 4 3Tracer 2 - 4 2 4Laser 5 - 4 5 5

Key 1 is low 5 is highNote For purchase price see fig. (a) and (b) of fig 2.6

Installation costs

Calibration costs

9

10

3

4

5

6

Table 2.7 Selection by economic factorsSpares costs

7

8

Operations costs

Maintenance costs

1

2

Group Type

Example-1Select a flowmeter for the following requirement:

a. Application : Custody Transfer Applicationb. Line size : 12 inchesc. Fluid : Natural Gasd. Operating pressure : : 20 bare. Operating Temperature : 300 +/- 50Cf. Uncertainty : 0.25% of actual flowg. Output : To interface with flow

computerh. Pipe work : No limitationi. Pressure drop at max flow : Medium

1. Groups to be considered : 1, 2, 4, 5, 10 Select L in Table – 2

2. For uncertainty 0.25% : 1, 2, 3, 4, 7 Table – 5

3. Flow rate : 6000 m3/hr in 12 inch line4. Line size : 1, 2, 3, 4, 5, 6, 7, 10

Table - 75. Pressure drop at max flow : 1, 2, 3, 4, 5, 6, 7, 8, 9,10

Table - 4

Answer : I Choice : Group 4II Choice : Group 2III Choice : Group 1

Example-2Select a flowmeter for the following requirement:a. Application : Acid Productionb. Line size : 25 mmc. Fluid : Hydrochloric Acidd. Operating pressure : 3 bare. Operating Temperature : 250 - 50Cf. Uncertainty : 1% of actual flowg. Output : To interface with flow

computerh. Pipe work : 3D upstream, 3D

downstream, Horizontali. Capital Investment : Item is not critical

1. For (a) and (c), select S in Table – 22. Groups to be considered : 1, 2, 3, 4, 5, 6, 7, 8, 103. For uncertainty 1% : 1, 3, 4, 5, 6, 7, 8 Table – 54. Flow rate : 3.5m3/s in 25 mm line5. Find velocity and re : 1, 3, 4, 6, 7, 8 Table- 86. Line size : 2, 3, 4, 5, 6, 7, 8, 97. Installation ( straight length) : 3, 6, 88. Economic Factors : 3, 6, 7, 8 Table 10

Answer : I Choice : Group 6II Choice : Group 3III Choice : Group 8

Table-2

Table-5

Table-8

Table-10

Example-3Select a flowmeter for the following requirement:

a. Application : Metro water supplyb. Line size : 1800 mmc. Fluid : waterd. Operating pressure : : 17 bare. Operating Temperature : 250 - 50Cf. Uncertainty : 1% of actual flowg. Output : To interface with flow

computerh. Pipe work : No limitationi. Capital Investment : Item is not critical

1. Groups to be considered : 1, 2, 4, 5, 6, 7, 9, 10 select D in Table – 2

2. For uncertainty 1% : 1, 2, 3, 4, 5, 6, 7, 8 ,9 Table – 53. Flow rate : 3700 l/s in 1800 mm line4. Find velocity and re : 1, 2, 3, 4, 5, 6, 7, 8, 9,10 Table- 85. Line size : 1, 2, 4, 6, 7, 106. Pressure drop at max flow : 1, 2, 3, 4, 5, 6, 7, 8, 9,10 7. Economic Factors : 1, 2, 3, 6, 7, 9 Table 10

Answer : I Choice : Group 6II Choice : Group 1III Choice : Group 2

Example–4Groups to be considered

Application : Steam Billing : N in Table 2Line size : 0.3 : 1, 2, 4, 5, 10 Table 8Fluid : Superheated steam : 1, 2, 4, 5, 10 Table 2Operation Pressure : 1000 psi : 1, 1, 5, 8 Table 6Operating Temperature : 300oC : 1, 2, 5, 8, 9 Table 6Uncertainty required : 0.5% of actual flow : 0, 4, 6, 8 Table 5

Flow rate : 4 kg/s to 45 kg/s

Output : Pulse for totalization

Pipe work : Not specified

Budget : Very limited : 1, 2, 6

Answer : No meter satisfies the specifications

Table -7

Table -4

Manufacturers are anxious to help customers pick the right flowmeter for a particular job.

Many provide questionnaires, checklists and specification sheets designed to obtain critical information necessary to match the correct flowmeter to the job.

• Technological Improvements of flowmeters must be considered.

• Availability of computer programs to perform tedious calculations often necessary for selecting flowmeters

Brooks InstrumentsFor selection and sizing of metal tube/glass tubeVariable area flowmeter

Fisher – RosemountFor selection of vortex meters Dos based

C. Johnson – YokogawaWindows based flow sizing program Admag magnetic flowmeters and Yewflow vortex flowmeters

The Foxboro Co, MassSoftware “Flow Expert”Interactive, Windows – basedMenu

Flowmeter review (Catalogue)Selection guideSizing for orifice plates/integral orifice assemblySizing for vortex meters, Coriolis meters, magmetersPhysical properties of fluids

Engineering Measurements Co.,

Program ‘Emcosize’InteractiveSelects different types of meters for same application

Software for Flowmeter selection

HoneywellSpecific application driven softwares for Coriolis, Magmeter and DP devicesHas build – in checks and warnings

Krohne, AmericaProgram ‘Corisize’, DOS – basedSelects the correctly sizes Coriolis meter Anticiplated pressure loss, liquid velocity and accuracy based on nominal flow are predicted

Endress + Hauser InstrumentsSizes 24 different types of flowmeters working or Coriolis/Vortex/Magmeter TechnologiesProvides data for 270 fluids

Abb InstrumentsSoftware ‘Genie’Selects the meter, prints out the part number and the catalogue price.

George Fischer Inc.,Selection of Signet paddle-wheel insertion meterSelection based on flow profile dependent on Reynolds N., Pipe I.D., Flow rate, Viscosity, DensityIndicates Whether a sensor will/may/will not work.

Flowmeter selection software

Windows based Flowmeter selection program as per BS 7405

Dos based Flowmeter Selection and Sizing software FMSEL 2.0

Windows based Flowmeter selection program as per BS 7405

Dos based Flowmeter Selection and Sizing software FMSEL 2.0

Flowmeter Sizing

Orifice with flange tappings

Orifice with corner tappings

Orifice with D and D/2 tappings

Classical Venturi tube

Long radius nozzle

ISA 1932 nozzle

Venturi nozzle (ISA inlet)

Meter Sizing in Turbine MetersTurbine meters are sized by volumetric flow rate. When sizing the meter, it is recommended that the application maximum flow rate is approximately 70 to 80 percent of the maximum flow rate. This results in a good flow range – 7 or 8:1.

For optimum performance and flow range, most turbine meters are designed to a nominal maximum velocity of 30ft/s (9.14m/s).

Consequently, if the turbine meter is selected to be of the same size as the pipeline, the meter flow range will be severely limited and will only be approximately 2 or 3:1.

If the turbine flow meter is sized on volumetric flow rate, it will be smaller than the pipeline.

Meter sizing in Vortex meters

The meter minimum flow rate is established by a Reynolds number of 10000, fluid density and a minimum acceptable shedding frequency for the electronics. The maximum flow rate is governed by the meter pressure loss(typically two velocity heads), the onset of cavitation with liquids and compressibility with gases. On low viscosity products like water, gasoline and liquid ammonia, and with an application maximum velocity of 15 ft/s (0.45m/s), vortex meters can have a rangeability of 40:1 with a pressure loss of approximately 4 psig. On liquid applications, it is necessary to verify that sufficient line pressure exists to prevent cavitation in the vortex meter.

Case Study – VenCorp Australia

                 Pipeline company crews in the Australian state of Victoria have installed 102 new ultrasonic, turbine and coriolis meters to measure at intermediate custody transfer points during a major gas industry reorganization and privatization.

Industry reformers have created one transmission company, three distribution companies and three retail companies from what was a single, vertically integrated organization in Victoria.

As a result of the restructuring, new custody transfer meters were required at the interfaces between the transmission and distribution systems

Of the 102 new meters installed in the 18-month, $20-million project, 18 multipath ultrasonic meters are used at large flow installations, 60 turbine meters for intermediate flows and 24 coriolis meters for small volumes.

Technologies were sought that would not only achieve the required measurement uncertainties, but would minimize the meter installations’ life cycle costs. Reduction or elimination of the need for regular re-calibration at pressure is highly desirable as the cost of removing the meter and shipping from Australia is high.

Multipath ultrasonic meters were generally chosen for category A and B meters, turbine meters for category C and coriolis meters for category D.

For large sites or sites where bi-directional flow is a possibility, multipath ultrasonic meters were chosen as they incorporate continuous internal diagnostic checks which indicate if any of the ultrasonic paths is fouled, if the meter is subject to external noise or if any of the ultrasonic transducers is deteriorating.

Monitoring the measured velocity of sound will show if there is any change in a critical dimension or if the reference clock has drifted. If there is any doubt about the meter’s operation, a dry calibration can be performed which will verify correct operation. In principle, there should be no need to return the meter for high-pressure calibration if there are no faults showing in the meter diagnostics and the measured velocity of sound is consistent with the gas passing through the meter.

Ultrasonic meters were installed at sites with peak hourly flows exceeding 40,000 m3/hr. The meter sizes range from 200 mm to 400 mm (8 to 16 in.).

In sizes less than 200 mm, cost considerations led to the selection of turbine meters. Turbine meters that comply with ISO 9951: Measurement of Gas Flow in Closed Conduits – Turbine Meters were chosen. They were tested to ensure compliance with minimum perturbation requirements with 2D upstream of the meter because this design maximized site-selection flexibility and minimized the metering-skid physical dimensions.

Turbine meter sizes below 50 mm were rejected because the turndown ratio suffers at the small sizes due primarily to dominant bearing effects.

For small-meter installations, coriolis meters were chosen because they offer high turndown ratio capability and can be calibrated with water and used to measure gas with an added uncertainty of less than 0.5%. Coriolis meters exhibit a turndown ratio in excess of 100:1 and cannot be damaged by excessive flows. Many small offtakes, especially country towns serving small populations of residential users without significant industry, have large turndown ratios with only a small maximum flowrate.

2006 Flowmeter User Study ResultsFlow Research (www.flowresearch.com) recently conducted a six-month survey of the flowmeter user community. The survey, which was undertaken in cooperation with Venture Development Corporation (www.vdc-corp.com) and Flow Control magazine, was conducted in the second half of 2005 via an Internet-based questionnaire

ThankYou !