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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”
FLOW INSTRUMENTATION 101
Your Logo Here
Overview – S.C. CONTROLS, INC.
Rep / Distributor / IntegratorEscondido / Irvine officesFounded in 1987Specializing in FLOW, LEVEL,
TEMPERATURE, DENSITY MEASUREMENTS
Degreed EngineersOffering 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 solutionsQuestions / Answers
Flow Measurement Theory
WHAT IS FLOW ??Measure of the velocity of a fluid per unit
area in a closed conduit; ie: pipe or ductFLOW = VELOCITY (fluid) X Area of Pipe
or Duct or StackFLOW = FPM X FT2 or IN2Q = 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 apartmentused for billing purposesMechanical flow meter with local rate and
totalRelative accuracy
FLOW - In our everyday lives
Gas Flow Meter - natural gas measurement of gas used for cooking and heatingMechanical Meter - turbine type
Liquid flow meter - Gasoline - at the local gas station where we pumped gas this morningPositive displacement type with output signal
to electronic counter for billingWe use flow meters every day to measure fluids we use.
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.
Basic Flow Theory 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
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
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
Density - LiquidsLiquids
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
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
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:
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
Energy FlowChilled/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
Flow Profiles & Reynolds Number
Re =
Re =
Re =
inertial forcesfrictional forces
density velocity diameterviscosity
V Dµ
ViscosityDynamic 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 *
ViscosityViscosity can be highly temperature dependent in liquids.
Steam/gas – 0.01 cP
Water – 1.0 cP
Honey – 300 cP
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
Repeatability
Not accurate, but repeatable
Not accurate, or repeatable
Accurate & Repeatable
Repeatability:
Differs from Accuracy
Measures the same all the time
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
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
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)
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
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
Orifice Plate Flowmeter
Orifice Plates
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
Variable orifice flow meter
Line sizes 2-8”Temp up to 842°F
(450°C) Accuracy ±1.0% of
rateGas and Steam
applicationsCompact
installation - 6 up and 3 down
Up to 100:1 turndown
Digital variable orifice flow meter
Line sizes 2-4”Saturated Steam
ONLY347°F (175°C)Accuracy ±2.0% of
flowInternal RTD for
Integrated mass flow measurement
Compact installation - 6 up and 3 down
Up to 50:1 turndown
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 rateGas and Steam ±1.0% of rate
Turndown up to 20:1 Vortex
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 rateGas and Steam ±1.5% of flow
rate test conditions Turndown up to 20:1 VBar
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 rateGas and Steam ±1.5% of rate
Turndown up to 25:1TMP
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
Transit Time Ultrasonic Flowmeter
Liquid applications-Clean2-100” (50 to 2540mm)Accuracy typically ±2.0%
of rateNon-IntrusiveNo wetted partsMultiple outputs
availableEZ-Logic menu driven
user interface Bi-DirectionalTransducer cable length
up to 300’Sono-Trak
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 METERS
FOR MEASURING GAS FLOW
WHAT IS A THERMAL MASS FLOW METER?
It is a Meter that directly measures the Gas Mass Flow based on the principle of conductive and convective heat transfer – more detail later…
MEASURE MASS FLOW RATE OR TOTALIZE COMMON GASES
Air (Compressed Air, Blower Air, Blast Furnace Air, Combustion Air, Plant Air, Make-Up Air)
Natural Gas Industrial (Plant Usage, Sub-Metering, Boiler Efficiency, Combustion Control)
Natural Gas Commercial & Governmental (Building Automation – Reduce Energy Costs, LEED Credits, Meet Regulations)
Digester Gas, Bio Gas, Landfill Gas (especially for EPA regulations and Carbon Credits)
Flare Gas (Vent Gas and Upset – Dual Range)Other: Propane, Nitrogen, Argon, CO2
WHAT DO THE SENSORS CONSIST OF?
The Sensors are RTDs, which are resistance temperature detectors
They consist of highly stable reference-grade platinum windings
In fact, we use the same material that is used as Platinum Resistance Standards at the National Institute of Standards (NIST)
THE BASIC PRINCIPLEThe RTDs are clad in a protective 316 SS sheath for
Industrial Environments
One of the RTDs is self-heated by the circuitry and serves as the Flow Sensor
The other RTD acts as a Reference Sensor. Essentially it is used for Temperature Compensation
SAGE PROPRIETARY SENSOR DRIVE CIRCUITRY
Circuitry maintains a constant overheat between the Flow Sensor and Reference Sensor
As Gas Flows by the Heated Sensor (Flow Sensor), the molecules of flowing gas carry heat away from this sensor, and the Sensor cools down as it loses energy
Circuit equilibrium is disturbed, and momentarily the delta T between the Heated Sensor and the Reference Sensor has changed
The circuit will automatically (within 1 second), replace this lost energy, by heating up the Flow Sensor so the overheat temperature is restored
HOW DO THE RTDs MEASURE MASS FLOW
The current required to maintain this overheat represents the Mass Flow signal
There is no need for external Temperature or Pressure devices
INSERTION STYLE½” Probes up to 24” longTypically for pipes from 1” up to 30”¾” Probes up to 60” LongTypically for very large pipes and ducts Or use multiple probes, one in each quadrant and
average in large ductsIsolation Valve Assemblies availableFlanged Mounting available (High P or T)Captive Flow Conditioners (2” – 24” Dia.)
INSERTIONS NEED STRAIGHT RUN (Min 10 up, 5 down)*
*If insufficient straight run, consider Sage inexpensive Captive Flow Conditioners
EEEE
CAPTIVE FLOW CONDITIONERS OPTIONALLY INSTALLED BY USERS UPSTREAM OF INSERTION METERSIF INSUFFICIENT STRAIGHT RUN
IN-LINE METERS¼” Flow Bodies up to
4” NPT or FlangedBuilt-in Flow Built-in Flow Conditioning (Conditioning (>>1/2”)1/2”)
TYPES OF MASS FLOW METERS
REMOTE MASS FLOW METERS
DIGITAL THERMAL MASS FLOW METERS
SAGE PRIMETM
Powerful State-of-The-Art Microprocessor Technology
High Performance Mass Flow Measurement at Low Cost-of-Ownership
Proprietary Digital Sensor Drive Circuit Provides Enhanced Signal Stability
Low Power Dissipation, under 2.5 Watts (<100 ma at 24 VDC)
SAGE PRIMETM
(Continued)High Contrast Photo-Emissive Organic
LEDs (OLEDs)Displays Calibration Milliwatts (mw) for
Ongoing Diagnostics (Zero Calibration Check)Modbus Compliant RS485 RTU
Communications (IEEE 32 Bit Floating Point)Remote Style has Lead-Length Compensation –
Up to 1000 Feet24 VDC or 115/230 VAC Power12 VDC Option (for Solar Energy)
SAGE PRIME DISPLAY (CONTINUED)
High Contrast OLEDs Visible even in SunlightGraphical Display – Displays Pctg of FS RateFlow Rate in any Units (per Sec, Min or Hour)Totalizes up to 9 digits, then rolls overDisplays Temperature in ºF or ºCContinuously Displays raw milliwatts (mw) for
ongoing Diagnostics (zero mw on Certificate)Diagnostic LEDs for Power and Modbus
INPUT/ OUTPUTS
24 VDC Power (draws less than 100 ma)115 VAC/ 230VAC or 12 VDC OptionalOutputs 4 – 20 ma of Flow RateOutputs 12 VDC Pulses of Totalized Flow (Solid
State, sourcing, transistor drive – 500ms Pulse)
Modbus® compliant RS485 Communications
ELECTRONICS MOUNTING
RECONFIGURABILITYBasis MODBUS ADDRESSER Software and
UlinxAdvanced ADDRESSER PLUSDONGLE shown below (no computer
needed)
THERMAL MFM ADVANTAGES (OVER OTHER TYPES OF TECHNOLOGIES)
Direct Mass Flow – No need for separate temperature or pressure transmitters
High Accuracy and Repeatability Turndown of 100 to 1 and resolution as much as
1000 to 1 Low-End Sensitivity – Detects leaks, and
measures as low as 5 SFPM!
ADDITIONAL BENEFITS(Pressure Independence)
15 Data Points at 110 psig (BP), than same output, even at 0 psig (No Back Pressure)
Separate 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 Mandate to Reduce Energy ConsumptionNeeds Assessments/Portable TestingPermanent Monitoring tied to Control
Systems - -NG, Air, N2
Compressed AirFacilities MonitoringSub-metering/BillingLeak DetectionEnergy ConservationCompressor OptimizationPerformance Testing
??????????????????????
QUESTIONS AND
ANSWERS
Complete solutions . . .
. . . to all your instrumentation needs !!!