FLOWMETERSELECTIONSEMINAR

AlanGraff

RLStoneCoI&CSalesManager

UpstateNY&NewEngland

A Leading Supplier of Flowmetersto HVAC & Industrial Marketplace

Magmeters Vortex & Swirl Turbine Thermal & Coriolis Mass BTU Meter Pitot, Wedge Orifice Plates, Venturi Positive Displacement Rotameter, Variable Area

DefineApplication BasicFacts

FlowingMedia(Steam,Water,Air,Gasetc) Density pressureandtemperature FlowRange,minimumtomaximum(turndownneeded)

Accuracy howstated?%ofrangeorspan Repeatability Straightrunrequirements&available EconomicConsiderations Initialcost,maintenancecost&operatingcosts

Whyarewehere?

Thereisno 1meterthatwillmeeteveryapplication

Everyapplicationneedstobelookedatindividually

Wecanmakesomegeneralizations!!!!!!

HOWMUCH (TOTAL)

HOWFAST (RATE)

FLOWMEASUREMENT

Flow Through A Pipe

Real WorldIdealized

Pipe Velocity Profile

VV

Flow Profile Correlation

Velocity profile is a predictable function of Reynolds number. Fluids with the same Reynolds number will have similar velocity profiles.

SteamWaterHeavy Crude

V

General Flow Terminology

Reynolds Number (RE) A single dimensionless parameter formed as the ratio of inertial to viscous forces . Magnitude indicates whether flow is laminar or turbulent

=

CharacteristicDimension*

(D)

Fluid Viscosity ()RE=

FluidDensity

(p)

FluidVelocity

(V)Inertia ForcesViscous Forces

* Usually inside pipe diameter.

Characterization of Fluid Flow

Types of FlowRE < 2100

RE >3000

*** Well documented & proven fully developed flow profiles

Transitional

Turbulent ***

Laminar

Volumetric Flowrate (Q)

Volume = Area x LengthVolume Flow = Area x Velocity

VA

Q

Mass Flowrate (m)

Where m = Mass FlowQ = Volume Flow = Fluid Density

= AV

Mass = Volume x Density

Mass Flow m = Qp

VA

m

Q=VA

MassvsVolumeFlowmeters

Whyareweconcerned? Howmuchdoesitreallymatter? Flowthrougha4linemeasuredinaAveragingPitot

Flow Rate 1000 cfm 1000 cfm

Pressure 5 psi 5 psi

Temperature 100 F 70 F

DP in WC 12.181 11.532

Thereisa6%errorjustbychangingdensity/temperatureslightlycanyoumetercope??

General Flow Terminology

Factors affecting flowmeter performance Process media

Liquid Gas

Density (Specific Gravity) Viscosity Pressure

Temperature Velocity

Flowmeter Performance

Accuracy Repeatability Linearity Rangeability

Types of Accuracy

% Rate % Full Scale % Span % Max DP

Accuracy

% Rate The percent accuracy value is constant and applied to the actual (or indicated) flowrate

Example:Flowrate 1% rate100 GPM 1 GPM50 GPM 0.5 GPM10 GPM .01 GPM

% Full Scale The absolute value of error (as expressed in engineering units)

Flowrate 1% Full Scale % Rate100 GPM 1 GPM 1%50 GPM 1 GPM 2%10 GPM 1 GPM 10%

Example:

Accuracy

Percent Error Versus Flow

Poor Repeatability Means Poor Accuracy

Good Accuracy Means Good Repeatability

Good Repeatability Does Not Necessarily Mean Good Accuracy

VolumetricFlowmeters

DP Turbine Vortex/Swirl Magnetic Target Ultrasonic Displacement

Note:canbeinferredmasswithcompensatingtransmitter

Differential Pressure Flowmeters

Flow Measurement Principles

PQ = K

ORIFICE PLATE(or FLOW TUBE) VENA

CONTRACTA

MANOMETER(or DP TRANSMITTER)h

Direction of Flow

DP Primary Elements

VariousOrificeConfiguration

FlowNozzle

VenturiFlowmeter

FlowTube

DPPrimaryElements

AveragingPitot

Accelabar CombinedPitot&Venturi

WedgeElement

Secondary Flow / DP Transmitter

Differential Pressure / Flow Transmitter

Square Root Extraction

DP Flowmeters

DIFFERENTIAL PRESSUREADVANTAGES

Use On Liquid, Gas, and Steam

Suitable for Extreme Temperatures and Pressures

No Moving Parts

Low Cost

DISADVANTAGES

Limited Rangeability

Effected By Changes In Density, Pressure, and Viscosity

Maintenance Intensive

Magnetic FlowmetersTheory of Operation

Magmeter Requirements

Process must be a liquid Minimum conductivity Meter must be full

Magnetic Flowmeters

MAGNETICADVANTAGES

No Moving Parts

Very Wide Rangeability

Ideal For Slurries

Unobstructed Flow Path

DISADVANTAGES

Liquid Must Be Conductive

Physical Pressure and Temperature Limits

Magnetic Flowmeters

No moving parts No pressure drop Flowrate independent of viscosity, temperature, and density Minimum upstream piping requirements Electronics interchangeable without regard to size Measure dirty liquids with solids Measure highly corrosive fluids Very large turndown Linear output

Advantages Over Other Technologies

Vortex Meter

Vortex MeterPrinciple of Operation

Q = V x A

Vortex

Vortex/Swirlmeter

ADVANTAGES

No Moving Parts

For Liquid, Gas, or Steam

Uneffected by Pressure, Temperature, or Density Changes.

Wide Rangeability

DISADVANTAGES

Span Limitations Due to Viscosity

Flow Profile Sensitive (Vortex)

VORTEX / SWIRLMETER

Swirlmeter

Principle of OperationPreamplifier

Swirler Sensor Deswirler

r = local radiusVA = axial velocity of flowVT = angular velocity of flowp = static pressure

Backflow

Housing

Swirlmeters

Benefits High Accuracy 0.50% of Rate

No Moving Parts

Minimal Upstream Piping

Measures Low Flows

Versatile

Electronics can be used for Diagnostics

Works with Entrained Liquids

Swirlmeter

Cut-Away ViewTechnical Data Measures liquids, gases and steam Available integral, remote, or flow

computer electronics Accuracy 0.50% rate Sizes 0.75" thru 16.0" Minimal upstream piping req. Flow as low as 1 GPM Excellent in light gas applications

Installation Length

Swirlmeter

15 D 5 D

25 D 5 D

50 D 5 D

Vortex 4Swirlmeter

90 elbow

Processcontrol valve

Reduction

3 D 1 D

3 D 1 D

5 D 1 D

min. 1.8 D

Turbine Meter

Turbine Meter

Principle of Operation

Rotor velocity is proportional to fluid velocity

Turbine Meter

High accuracy (.5% of rate) High rangeability (up to 50:1) Compact design Fast response time Broad range of sizes Clean water applications only NIST Traceable Factory Calibration Low cost, Easy to install In and out of line, under pressure

Turbine Meter

Straight pipe run requirements Process fluid lubricity Reynolds number constraintsViscosityDensity

Maintenance & recalibration

Performance Considerations

Turbine Flowmeters

TURBINEADVANTAGES

High Accuracy

Suitable for Extreme Temperatures and Pressures

Can Be Used On Gas or Liquid

DISADVANTAGES

Only For Low Viscosities

Moving Parts

Sensitive to Flow Profile

Positive Displacement Flowmeters

PD Flowmeters

Helical gear Nutating disk Oscillating

piston Oval gear Rotary

Types

Positive Displacement Meter

Typical Principle of Operation

Schematic of a nutating-disk meter

Schematic of a rotary-vane flowmeter Schematic of a

lobed-impeller flowmeter

PD Flowmeters

Ideal for viscous fluids Custody transfer Batching Minimal straight piping

requirements

Advantages

Ultrasonic Flowmeters

Doppler Time of

flight

Types

DopplerFlowmeter

Ultrasonic FlowmetersPrinciple of Operation

Ultrasonic FlowmetersPrinciple of Operation

Transit-TimeFlowmeter

Ultrasonic Flowmeters

Reynolds number constraints Entrained gas or particles for doppler Clean liquids for time of flight Installed without process shut down Straight upstream piping

requirements

Performance Considerations

Ultrasonic

ULTRASONICADVANTAGES

No Moving Parts

Unobstructed Flow Passage

Wide Rangeability

DISADVANTAGES

For Liquids Only (limited gas)

Flow Profile Dependent

Errors Due To Deposits

V

MassFlowmeter

DirectMeasurement

ThermalDispersion Coriolis

CoriolisMassFlowmeter

Coriolis

Coriolis

CORIOLISADVANTAGES

Direct Mass Measurement

High Accuracy

Additional Density Measurement

Uneffected By Flow Profile

DISADVANTAGES

High Purchase Price

High Installation Cost

Size Limitations

Vibration Sensitive

ThermalDispersion

ThermalDispersionMassFlowmeter

Gasapplicationonly Relativelyinexpensive Easytoinstallandremoveunderpressure Accuracy0.5% Turndown,100:1 Capableofmonitoringextremelylowflows Truemassflowmeter(compensatesfortemperature/pressure)

PipingConsiderations

Alwaysneedafullpipe

Properup/downdiameter

BTUMonitoring

Summary Each Application is Different

FlowingMedia(egSteam,Water,Air,Gasetc)Density pressureandtemperatureFlowRange,minimumtomaximum(turndownneeded)Accuracy howstated?%ofrangeorspanRepeatabilityStraightrunrequirements&availableMaintenanceandreliability

GeneralHVACRecommendations

Steam:AccelabarorSwirl

ChilledorHotWater:HotTapInsertTurbine

NaturalGasorAir:ThermalDispersion

FuelOil:CoriolisorWedge