FLOW INSTRUMENTATION 101

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Dave Schmitt

Escondido / Irvine“Serving the Southwest’s

Instrumentation Needs Since 1987”

Dave Schmitt

Escondido / Irvine“Serving the Southwest’s

Instrumentation Needs Since 1987”

Overview – S.C. CONTROLS, INC.

Rep / Distributor / Integrator Escondido / Irvine offices Founded in 1987 Specializing in FLOW, LEVEL,

TEMPERATURE, DENSITY MEASUREMENTS

Degreed Engineers Offering solutions not just sales

Overview

Briefly describe the theory of flow measurements

Outline different types of flow meters.

Discuss advantages/ disadvantages in applications.

Present examples of instruments for measurement solutions

Questions / Answers

Flow Measurement Theory

WHAT IS FLOW ??– Measure of the velocity of a fluid per unit

area in a closed conduit; ie: pipe or duct– FLOW = VELOCITY (fluid) X Area of

Pipe or Duct or Stack– FLOW = FPM X FT2 or IN2– Q = AV (Area X velocity)– Q = ρ AV (density x area x vel)

• Mass flow

FLOW - In our everyday lives

Water flow meter at our home or apartment– used for billing purposes– Mechanical flow meter with local

rate and total– Relative accuracy

FLOW - In our everyday lives

Gas Flow Meter - natural gas measurement of gas used for cooking and heating– Mechanical Meter - turbine type

Liquid flow meter - Gasoline - at the local gas station where we pumped gas this morning– Positive displacement type with output

signal to electronic counter for billing

We use flow meters every day to measure fluids we use.

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Why meter?

• Business Need• Mitigate rising energy costs • Manage energy consumption efficiently• Apportion energy costs by usage and not

square footage, creating behavior change

You cannot control what you do not measure.

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Volumetric Flow Mass Flow Density - Liquid Density - Steam Actual vs. Standard Flow - Gas Energy Flow - Water Flow Profiles & Reynolds Number Viscosity Accuracy Repeatability Straight Run Requirements Meter Installation

Basic Flow Theory

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Volumetric Flow (all fluids)

Q = A V

= ft

=

ft sec*

*

²ft sec³

where:

Q = volumetric flow

A = cross sectional area ( ft )

V = average fluid velocity ( )ft sec

ft sec³

²

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Mass Flow

where:

m = mass flow ( )

= density ( )

Q = average fluid velocity ( )

A = cross sectional area ( ft )

V = average fluid velocity ( )

lbs sec

²

ft sec

ft sec

m = Q = A V

= ft

=

* **

² ft sec* *lbs ft ³

lbs sec

lbs ft ³

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Density - Liquids

Liquids

The density of a liquid is inversely proportional to temperature:

1T

8.2877100

8.303790

8.317680

8.32970

8.337860

8.34350

8.345140

8.343632

Weight Density

Lbs/gal

Temperature

°F

WATER

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Density - Gases

where: = Density ( )

= absolute pressure (psia) = 14.7 + Pgage

SG =Specific Gravity

= absolute temperature = F° + 460 = ° Rankin

lbs ft3

Ta

a =

2.7 SG

Ta

Density of Gas:

a

Gases

= 1T

The density of a gas varies proportionally with pressure and inversely with temperature:

a

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Density - Steam

3.7406001541.00

3.1005801324.30

2.5805601131.80

2.150540361.50

1.780520811.40

1.480500680.00

.820440381.20

0.536400247.10

0.338360152.92

0.20332089.6

Densitylbs/ft³

Temperature°F

Pressurepsia

Saturated Steam Table

0.14350080

0.15344080

0.16140080

0.17036080

0.18132080

0.03550020

0.03844020

0.03940020

0.04136020

0.04432020

Densitylbs/ft³

Temperature°F

Pressurepsia

Superheated Steam Table

Superheated steam:Saturated steam:

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Actual vs. Standard Flow - Gas

Standard Volume Flow:

Gas flow in standard units relates the volume flow of gas to the same amount of mass flow of gas at standard conditions:

where:Q = Q

standard actual

operating

standard conditions

= specific gravity ( , at standard conditions )

= density of gas at operating pressure and temperature

= density of gas at standard conditions (at 14.7 psia, 60°F)

= standard time or

standard time

³ft unitQstandard

Qactual

operating

standard

= actual volumetric flow (ACFM, ACFH, etc…)

gas air

³m unit

SG

Actual Volume Flow:Q = V A (actual , , etc)

(actual ,hr, , etc)

* ³ft sec

³m sec

³ft min

³m sec

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Energy Flow

Chilled/hot water energy (Btu) calculations require (1) flow and (2) temperature inputs.

Btu is defined as the amount of energy required to raise the temperature of 1lb water at 39°F by 1°F.

where:

E = energy flow ( )

m = mass flow ( )

A = cross sectional area (ft²)

V = average fluid velocity ( ) = density ( )

h = Btu’s (heat content) of water at supply temperature ( )

h = Btu’s (heat content) of water at return temperature ( )

Btu sec

lbs sec

ft sec

Btu lbs

lbs ³ft

Btu lbs

s

r

lbsft³

ftsec

E = m (h – h )

E = A V (h - h )

E = ft²

E =

s r

rs

Btulbs

Btusec

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Flow Profiles & Reynolds Number

Re =

Re =

Re =

inertial forcesfrictional forces

density velocity diameterviscosity

V Dµ

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Viscosity

Dynamic viscosity

cP (centipoise)

Kinematic Viscosity

cst (centistoke)

A measure of how freely a fluid flows:

where:V = kinematic viscosity

V = dynamic viscosity

SG = specific gravity

cP

cstV = Vcst SGcP *

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ViscosityViscosity can be highly temperature dependent in liquids.

Steam/gas – 0.01 cP

Water – 1.0 cP

Honey – 300 cP

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Accuracy

% of Rate or Reading

Error = % of rate measurement

% of Full Scale

Error = % of full scale full scale flow

ACCURACY +/-1%

% of Rate Max flow 1,000lb/h = 1,010 to 990 lb/hMin flow 100 lb/h = 101 to 99 lb/h

% Full scale (FS)Max flow 1,000 lb/h = 1,010 to 990 lb/hMin flow 100 lb/h = 110 (100 + 10) lb/h

to 90 (100 - 10) lb/h

i.e. +/- 10% error at minimum flow

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Repeatability

Not accurate, but repeatable

Not accurate, or repeatable

Accurate & Repeatable

Repeatability:

Differs from Accuracy

Measures the same all the time

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Installation – Straight RunStraight run requirements

Minimum 10 pipe diameters upstream and 5 pipe diameters downstream required to get proper flow profile

Less straight run affects meter accuracy

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Installation – Meter Location

Top View

Top View

Install before valve to avoid air

Vertical orientation– insure full pipe

Liquid horizontal orientation– insure full pipe

Gas & steam horizontal orientation – insure no condensate

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TechnologiesTechnology Operating

PrincipleAdvantages Disadvantages Fluids

Measured

DP(Differential Pressure)Orifice platePitot tubeVariable areaVenturiV-ConeAccelabar

An obstruction in the flow, measure pressure differential before and after the obstruction

Low initial cost No moving parts Handle dirty media Easy to use Well understood technology Supported by AGA and API

Not highly accurate, particularly in gas flow Orifice plate and pitot tube can become clogged High maintenance to maintain accuracy Typically low turndown Pressure drop

LiquidsGases Steam

VortexInlineInsertion

Bluff body creates alternating vortices, vortex shedding frequency equal to fluid velocity

High accuracy No moving parts No maintenance Measures dirty fluids

Can be affected by pipe vibration Cannot measure low flows

Liquids GasesSteam

TurbineInlineInsertionDual turbine

Turbine rotates as fluid passes by, fluid velocity equal to blade rotational frequency

High accuracy Low flow rates Good for steam Wide turndown

Moving parts require higher maintenance Clean fluids only

LiquidsGasesSteam

MagneticMagElectromagnetic

Measures voltage generated by electrically conductive liquid as it moves through a magnetic field, induced voltage is equal to fluid velocity

High Accuracy Wide turndown Bi-directional No moving parts No pressure loss to system

Conductive fluids only Expensive to use on large pipes

Conductive liquids (condensate)

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Technologies Cont’dTechnology Operating

PrincipleAdvantages Disadvantages Fluids

Measured

Transit-timeUltrasonic

Fluid velocity measured by time arrival difference of sound waves from upstream and downstream transducers

Low cost clamp-on installation Non-intrusive No maintenance Bi-directional Best for larger pipes

Typically not used on pipes < 2” Less accurate than inline or insertion meters Used primarily for liquids Susceptible to changes in fluid sonic properties

Most liquids (condensate)Gas (when spool-piece)

DopplerUltrasonic

Fluid velocity measured by sensing signals from reflective materials within the liquid and measuring the frequency shift due to the motion of these

reflective materials

Low-cost, clamp-on installation Non-intrusive Measures liquids containing particulates or bubbles Low maintenance Best for larger pipes

Can’t be used in clean liquids Less accurate than in-line or transit-time ultrasonic

Most liquids containing reflective materials

Thermal Mass

Measure heat loss of heated wire thermistor in fluid flow

Measure flow at low pressure Relative low cost Measure fluids not dense enough for mechanical technologies Easier to maintain than DP meter

Susceptible to sensor wear and failure Not very accurate Limited to fluids with known heat capacities

Gases

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The orifice plate is a differential pressure flow meter (Primary element).

Based on the work of Daniel Bernoulli the relationship between the velocity of fluid passing through the orifice is proportional to the square root of the pressure loss across it.

To measure the differential pressure when the fluid is flowing, connections are made from the upstream and downstream pressure tappings to a secondary device known as a DP (Differential Pressure) cell.

Orifice Plate Flowmeter

Fig. 4.3.1 Orifice plate

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Orifice Plate Flowmeter

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Advantages: Low cost, especially on large

sizes No need for recalibration Widely accepted

Disadvantages: Poor turndown (4:1 typical) Long installations (20D to 30D) Accuracy dependant on

geometry.

Complete Customer Data Sheet:

Customer details

Fluid

Operating pressure

Operating temperature

Estimate flow rate

Line size, Pipe Schedule, Material

Flange Specification

Required package option

Orifice Plates

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Variable orifice flow meter Line sizes 2-8” Temp up to 842°F

(450°C) Accuracy ±1.0% of

rate Gas and Steam

applications Compact installation -

6 up and 3 down Up to 100:1 turndown

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Digital variable orifice flow meter

Line sizes 2-4” Saturated Steam ONLY 347°F (175°C) Accuracy ±2.0% of

flow Internal RTD for

Integrated mass flow measurement

Compact installation - 6 up and 3 down

Up to 50:1 turndown

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Vortex Flowmeter

Liquid, Gas, and Steam 1-12” (25 to 300mm) Temperature up to 750°F(400°C) EZ-Logic menu-driven user

interface In-process removable sensor

(below 750psig) Fully welded design with no leak

path Optional remote mount electronic Accuracy

Liquid ±0.7% of rate Gas and Steam ±1.0% of rate

Turndown up to 20:1 Vortex

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Insertion Vortex Meter Liquid, Gas, and Steam Model 60/60S Hot Tap, retractable Model 700 Insertion low temp, low

pressure Model 910/960 Hot tap, retractable

960-high temp up to 500°F (260°C), high pressure

Optional Temperature and/or Pressure Transmitter

Line sizes 3-80” (76 to 2032mm) No moving parts EZ-Logic menu driven user interface Accuracy

Liquid ±1.0% of rate Gas and Steam ±1.5% of flow rate

test conditions Turndown up to 20:1 VBar

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Turbo-Bar Insertion Turbine Flow Meter Liquid, Gas, and Steam Liquid flow velocity down to 1 ft/sec Model 60/60S Hot Tap, retractable Model 700 Insertion low temp, low

pressure Model 910/960 Hot tap, retractable

960-high temp up to 750°F (400°C), high pressure

Optional Pressure and/or Temperature Transmitter

Line sizes 3-80” (76 to 2032mm) EZ-Logic menu driven user interface Nominal Accuracy

Liquids ±1.0% of rate Gas and Steam ±1.5% of rate

Turndown up to 25:1TMP

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Low-cost Water Vortex Meter No Moving Parts Flow Range 1 to 15 ft/s (0.3 to 4.5 m/sec) Accuracy ±1.0% of Full Scale 1/2 to 20” Line Size Microprocessor-based electronics with

optional local display Maximum Fluid temperature 160°F

(70°C) Model 2300 for acids, solvents, De-

ionized, and ultra pure water (1/2 to 8”) Model 2200 Fixed Insertion for (2 to 20”) Model 1200 for water, water/glycol (1-3”) Model 3100 retractable insertion (3-20”) Models 1200 and 2200 have Aluminum

Enclosure option for wet environments or heavy industrial installations

1200

2200

3100

2300

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Transit Time Ultrasonic Flowmeter

Liquid applications-Clean 2-100” (50 to 2540mm) Accuracy typically ±2.0%

of rate Non-Intrusive No wetted parts Multiple outputs available EZ-Logic menu driven user

interface Bi-Directional Transducer cable length

up to 300’Sono-Trak

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Electromagnetic Flowmeter Field Serviceable Design

Field replaceable sensors and coils

No Liner Required No liner failure

Solid State Sensor Design Encapsulated coil and electrode

assembly insensitive to shock and Vibration

Plurality of Sensors Uniquely powerful magnetic field

Non-standard Flow Tube Lengths Easy replacement of existing meters

Measures Low Conductivity Media Conductivity down to 0.8 µS/cm

THERMAL MASS FLOW METERSTHERMAL MASS FLOW METERS

FOR MEASURING GAS FLOWFOR MEASURING GAS FLOW

WHAT IS A THERMAL MASS WHAT IS A THERMAL MASS FLOW METER?FLOW METER?

It is a Meter that directly measures the It is a Meter that directly measures the Gas Mass Flow based on the principle Gas Mass Flow based on the principle of conductive and convective heat of conductive and convective heat transfer – more detail later…transfer – more detail later…

MEASURE MASS FLOW RATE MEASURE MASS FLOW RATE OR TOTALIZE COMMON GASESOR TOTALIZE COMMON GASES

Air (Compressed Air, Blower Air, Blast Furnace Air (Compressed Air, Blower Air, Blast Furnace Air, Combustion Air, Plant Air, Make-Up Air)Air, Combustion Air, Plant Air, Make-Up Air)

Natural Gas Industrial (Plant Usage, Sub-Natural Gas Industrial (Plant Usage, Sub-Metering, Boiler Efficiency, Combustion Control)Metering, Boiler Efficiency, Combustion Control)

Natural Gas Commercial & Governmental Natural Gas Commercial & Governmental (Building Automation – Reduce Energy Costs, (Building Automation – Reduce Energy Costs, LEED Credits, Meet Regulations)LEED Credits, Meet Regulations)

Digester Gas, Bio Gas, Landfill Gas (especially Digester Gas, Bio Gas, Landfill Gas (especially for EPA regulations and Carbon Credits)for EPA regulations and Carbon Credits)

Flare Gas (Vent Gas and Upset – Dual Range)Flare Gas (Vent Gas and Upset – Dual Range) Other: Propane, Nitrogen, Argon, CO2Other: Propane, Nitrogen, Argon, CO2

WHAT DO THE SENSORS WHAT DO THE SENSORS CONSIST OF?CONSIST OF?

The Sensors are RTDs, which are resistance The Sensors are RTDs, which are resistance temperature detectorstemperature detectors

They consist of highly stable reference-They consist of highly stable reference-grade platinum windingsgrade platinum windings

In fact, we use the same material that is In fact, we use the same material that is used as Platinum Resistance Standards at used as Platinum Resistance Standards at the National Institute of Standards (NIST) the National Institute of Standards (NIST)

THE BASIC PRINCIPLETHE BASIC PRINCIPLE The RTDs are clad in a protective 316 SS sheath for The RTDs are clad in a protective 316 SS sheath for

Industrial EnvironmentsIndustrial Environments

One of the RTDs is self-heated by the circuitry and One of the RTDs is self-heated by the circuitry and serves as the Flow Sensorserves as the Flow Sensor

The other RTD acts as a Reference Sensor. Essentially it The other RTD acts as a Reference Sensor. Essentially it is used for Temperature Compensationis used for Temperature Compensation

SAGE PROPRIETARY SENSOR SAGE PROPRIETARY SENSOR DRIVE CIRCUITRYDRIVE CIRCUITRY

Circuitry maintains a constant overheat between Circuitry maintains a constant overheat between the Flow Sensor and Reference Sensorthe Flow Sensor and Reference Sensor

As Gas Flows by the Heated Sensor (Flow As Gas Flows by the Heated Sensor (Flow Sensor), the molecules of flowing gas carry heat Sensor), the molecules of flowing gas carry heat away from this sensor, and the Sensor cools away from this sensor, and the Sensor cools down as it loses energydown as it loses energy

Circuit equilibrium is disturbed, and Circuit equilibrium is disturbed, and momentarily the delta T between the Heated momentarily the delta T between the Heated Sensor and the Reference Sensor has changedSensor and the Reference Sensor has changed

The circuit will automatically (within 1 second), The circuit will automatically (within 1 second), replace this lost energy, by heating up the Flow replace this lost energy, by heating up the Flow Sensor so the overheat temperature is restoredSensor so the overheat temperature is restored

HOW DO THE RTDsHOW DO THE RTDs MEASURE MASS FLOW MEASURE MASS FLOW

The current required to The current required to maintain this overheat maintain this overheat represents the Mass Flow represents the Mass Flow signalsignal

There is no need for external There is no need for external Temperature or Pressure Temperature or Pressure devices devices

INSERTION STYLEINSERTION STYLE ½” Probes up to 24” long½” Probes up to 24” long Typically for pipes from 1” up to 30”Typically for pipes from 1” up to 30” ¾” Probes up to 60” Long¾” Probes up to 60” Long Typically for very large pipes and ducts Typically for very large pipes and ducts Or use multiple probes, one in each Or use multiple probes, one in each

quadrant and average in large ductsquadrant and average in large ducts Isolation Valve Assemblies availableIsolation Valve Assemblies available Flanged Mounting available (High P or T)Flanged Mounting available (High P or T) Captive Flow Conditioners (2” – 24” Dia.)Captive Flow Conditioners (2” – 24” Dia.)

INSERTIONS NEED STRAIGHT INSERTIONS NEED STRAIGHT RUN (Min 10 up, 5 down)*RUN (Min 10 up, 5 down)*

*If insufficient straight run, consider Sage inexpensive *If insufficient straight run, consider Sage inexpensive Captive Flow ConditionersCaptive Flow Conditioners

EEEE

CAPTIVE FLOW CONDITIONERS CAPTIVE FLOW CONDITIONERS OPTIONALLY INSTALLED BY USERSOPTIONALLY INSTALLED BY USERS UPSTREAM OF INSERTION METERS UPSTREAM OF INSERTION METERS

IF INSUFFICIENT STRAIGHT RUNIF INSUFFICIENT STRAIGHT RUN

IN-LINE METERSIN-LINE METERS ¼” Flow Bodies up to ¼” Flow Bodies up to

4” NPT or Flanged4” NPT or FlangedBuilt-in Flow Built-in Flow Conditioning (Conditioning (>>1/2”)1/2”)

TYPES OF MASS FLOW METERS TYPES OF MASS FLOW METERS

REMOTE MASS FLOW METERS REMOTE MASS FLOW METERS

DIGITAL THERMAL MASS FLOW DIGITAL THERMAL MASS FLOW METERSMETERS

SAGE PRIMESAGE PRIMETMTM

Powerful State-of-The-Art Powerful State-of-The-Art Microprocessor TechnologyMicroprocessor Technology

High Performance Mass Flow High Performance Mass Flow Measurement at Low Cost-of-OwnershipMeasurement at Low Cost-of-Ownership

Proprietary Digital Sensor Drive Circuit Proprietary Digital Sensor Drive Circuit Provides Enhanced Signal StabilityProvides Enhanced Signal Stability

Low Power Dissipation, under 2.5 Watts Low Power Dissipation, under 2.5 Watts (<100 ma at 24 VDC)(<100 ma at 24 VDC)

SAGE PRIMESAGE PRIMETMTM

(Continued)(Continued) High Contrast Photo-Emissive Organic High Contrast Photo-Emissive Organic

LEDs (OLEDs)LEDs (OLEDs) Displays Calibration Milliwatts (mw) for Displays Calibration Milliwatts (mw) for

Ongoing Diagnostics (Zero Calibration Check)Ongoing Diagnostics (Zero Calibration Check) Modbus Compliant RS485 RTU Modbus Compliant RS485 RTU

Communications (IEEE 32 Bit Floating Point)Communications (IEEE 32 Bit Floating Point) Remote Style has Lead-Length Compensation Remote Style has Lead-Length Compensation

– Up to 1000 Feet– Up to 1000 Feet 24 VDC or 115/230 VAC Power24 VDC or 115/230 VAC Power 12 VDC Option (for Solar Energy)12 VDC Option (for Solar Energy)

SAGE PRIME DISPLAY SAGE PRIME DISPLAY (CONTINUED)(CONTINUED)

High Contrast OLEDs Visible even in SunlightHigh Contrast OLEDs Visible even in Sunlight Graphical Display – Displays Pctg of FS RateGraphical Display – Displays Pctg of FS Rate Flow Rate in any Units (per Sec, Min or Hour)Flow Rate in any Units (per Sec, Min or Hour) Totalizes up to 9 digits, then rolls overTotalizes up to 9 digits, then rolls over Displays Temperature in ºF or ºCDisplays Temperature in ºF or ºC Continuously Displays raw milliwatts (mw) for Continuously Displays raw milliwatts (mw) for

ongoing Diagnostics (zero mw on Certificate)ongoing Diagnostics (zero mw on Certificate) Diagnostic LEDs for Power and ModbusDiagnostic LEDs for Power and Modbus

INPUT/ OUTPUTSINPUT/ OUTPUTS

24 VDC Power (draws less than 100 ma)24 VDC Power (draws less than 100 ma) 115 VAC/ 230VAC or 12 VDC Optional115 VAC/ 230VAC or 12 VDC Optional Outputs 4 – 20 ma of Flow RateOutputs 4 – 20 ma of Flow Rate Outputs 12 VDC Pulses of Totalized Flow Outputs 12 VDC Pulses of Totalized Flow (Solid (Solid

State, sourcing, transistor drive – 500ms Pulse)State, sourcing, transistor drive – 500ms Pulse)

Modbus® compliant RS485 CommunicationsModbus® compliant RS485 Communications

ELECTRONICS MOUNTINGELECTRONICS MOUNTING

RECONFIGURABILITYRECONFIGURABILITY

Basis MODBUS ADDRESSER Software and Basis MODBUS ADDRESSER Software and UlinxUlinx

Advanced ADDRESSER PLUSAdvanced ADDRESSER PLUS DONGLE shown below (no computer DONGLE shown below (no computer

needed)needed)

THERMAL MFM ADVANTAGESTHERMAL MFM ADVANTAGES (OVER (OVER OTHEROTHER TYPES OF TECHNOLOGIES) TYPES OF TECHNOLOGIES)

Direct Mass Flow – No need for separate Direct Mass Flow – No need for separate temperature or pressure transmitterstemperature or pressure transmitters

High Accuracy and Repeatability High Accuracy and Repeatability Turndown of 100 to 1 and resolution as Turndown of 100 to 1 and resolution as

much as 1000 to 1much as 1000 to 1 Low-End Sensitivity – Detects leaks, and Low-End Sensitivity – Detects leaks, and

measures as low as 5 SFPM!measures as low as 5 SFPM!

ADDITIONAL BENEFITSADDITIONAL BENEFITS(Pressure Independence)(Pressure Independence)

15 Data Points at 110 psig (BP), than same output, even at 0 psig (No Back Pressure)

Separate Rear EnclosureSeparate Rear Enclosure The rear compartment,

which is separated from the electronics, has large, easy-to-access and well marked terminals, for ease of customer wiring

Building Automation Contractors Building Automation Contractors

Mandate to Reduce Energy Mandate to Reduce Energy ConsumptionConsumption

Needs Assessments/Portable TestingNeeds Assessments/Portable Testing Permanent Monitoring tied to Control Permanent Monitoring tied to Control

Systems - -NG, Air, N2Systems - -NG, Air, N2

Compressed AirCompressed Air

Facilities MonitoringFacilities Monitoring Sub-metering/BillingSub-metering/Billing Leak DetectionLeak Detection Energy ConservationEnergy Conservation Compressor OptimizationCompressor Optimization Performance TestingPerformance Testing

??????????????????????

QUESTIONS AND

ANSWERS

Complete solutions . . .

. . . to all your instrumentation needs !!!