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FLOW
INSTRUMENTATION 101
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.
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.
7
Basic Flow Theory
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8
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 ² * ft sec
= ft ³ sec
where:
Q = volumetric flow ft ³ sec
A = cross sectional area ( ft ² )
V = average fluid velocity ( ft sec
9
)
Mass Flow
 = Q  = A V 
m
*
* *
= ft ² * ft sec * lbs ft ³
= lbs sec
where:

m = mass flow ( lbs sec )
 = density ( lbs ft ³ )
Q = average fluid velocity ( ft sec )
A = cross sectional area ( ft ² )
V = average fluid velocity ( ft sec )
10
Density - Liquids
Liquids
The density of a liquid is inversely proportional to
temperature:
WATER
 1 T
11
Temperature
°F
Weight Density
Lbs/gal
32
8.3436
40
8.3451
50
8.343
60
8.3378
70
8.329
80
8.3176
90
8.3037
100
8.2877
Density - Gases
Gases
The density of a gas varies proportionally with pressure and
inversely with temperature:
 = a
1
T
Density of Gas:
 =
2.7  a  SG
Ta
where:
 = Density ( lbs ft 3 )
a = absolute pressure (psia) = 14.7 + Pgage
SG =Specific Gravity
Ta = absolute temperature = F° + 460 = ° Rankin
12
Density - Steam
Saturated steam:
Superheated steam:
Saturated Steam Table
13
Superheated Steam Table
Pressure
psia
Temperature
°F
Density
lbs/ft³
Pressure
psia
Temperature
°F
Density
lbs/ft³
89.6
320
0.203
20
320
0.044
152.92
360
0.338
20
360
0.041
247.10
400
0.536
20
400
0.039
381.20
440
.820
20
440
0.038
680.00
500
1.480
20
500
0.035
811.40
520
1.780
80
320
0.181
361.50
540
2.150
80
360
0.170
1131.80
560
2.580
80
400
0.161
1324.30
580
3.100
80
440
0.153
1541.00
600
3.740
80
500
0.143
Actual vs. Standard Flow - Gas
Actual Volume Flow:
Q = V * A (actual ft³ sec, ft³ min, etc)
(actual m³ sec,hr, m³ sec, etc)
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:
Qstandard
= Qactual
 operating
 standard conditions
where:
Qstandard
= standard ft³ unit time or
standard m³ unit time
Qactual
= actual volumetric flow (ACFM, ACFH, etc…)
SG
= specific gravity ( gas air , at standard conditions )
operating
standard
14

= density of gas at operating pressure and temperature
= density of gas at standard conditions (at 14.7 psia, 60°F)
Energy Flow

E = m (hs – hr )

E = A V  (h s - h r )

ft
lbs
Btu
E = ft²  sec  ft³  lbs
 Btu
E=
sec
where:
15

Chilled/hot water energy (Btu) calculations require
(1) flow and
(2) temperature inputs.
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Btu is defined as the amount of energy required to
raise the temperature of 1lb water at 39°F by 1°F.
 = energy flow (Btu
E
 = mass flow
m
)
sec
(lbs sec )
A = cross sectional area (ft²)
V = average fluid velocity ( ft sec)
 = density ( lbs
ft³
)
hs = Btu’s (heat content) of water at supply temperature
hr
(Btu lbs)
= Btu’s (heat content) of water at return temperature (Btu lbs)
Flow Profiles & Reynolds Number
16
Re =
inertial forces
frictional forces
Re =
density velocity 
diameter
viscosity
Re =
  V D
µ
Viscosity
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Dynamic viscosity
cP (centipoise)
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Kinematic Viscosity
cst (centistoke)
A measure of how freely a fluid flows:
VcP = Vcst *SG
where:
Vcst = kinematic viscosity
V cP = dynamic viscosity
SG = specific gravity
17
Viscosity
Viscosity can be highly temperature dependent in liquids.
Steam/gas – 0.01 cP
Water – 1.0 cP
Honey – 300 cP
18
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/h
Min flow 100 lb/h = 101 to 99 lb/h
% Full scale (FS)
Max flow 1,000 lb/h = 1,010 to 990 lb/h
Min 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
Accurate & Repeatable
Repeatability:
Differs from Accuracy
Not accurate,
or repeatable
Measures the same all the time
Not accurate,
but repeatable
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Installation – Straight Run
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Straight run requirements

Minimum 10 pipe diameters upstream and 5 pipe diameters downstream required
to get
proper flow profile
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Less straight run affects meter accuracy
Installation – Meter Location
Install before valve to avoid air
Vertical orientation– insure full
pipe
Liquid horizontal orientation–
insure full pipe
Gas & steam horizontal orientation
– insure no condensate
22
Top View
Top View
Orifice Plate Flowmeter
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.
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Fig. 4.3.1 Orifice plate
Orifice Plate Flowmeter
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Orifice Plates
Advantages:
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Low cost, especially on large
sizes
Complete Customer Data Sheet:
Customer details
Fluid
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No need for recalibration
Operating pressure
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Widely accepted
Operating temperature
Estimate flow rate
Disadvantages:
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Poor turndown (4:1 typical)
Long installations (20D to 30D)
Accuracy dependant on
geometry.
Line size, Pipe Schedule, Material
Flange Specification
Required package option
Variable orifice flow meter
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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
Digital variable orifice flow meter
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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
Vortex Flowmeter
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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
Insertion Vortex Meter
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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
Turbo-Bar Insertion Turbine Flow Meter
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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 25:1
TMP
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Low-cost Water Vortex Meter
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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, Deionized, 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
2200
2300
1200
3100
Transit Time
Ultrasonic Flowmeter
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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
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Field Serviceable Design
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Field replaceable sensors and coils
No Liner Required
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No liner failure
Solid State Sensor Design
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Encapsulated coil and electrode
assembly insensitive to shock and
Vibration
Plurality of Sensors
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Uniquely powerful magnetic field
Non-standard Flow Tube Lengths
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Easy replacement of existing meters
Measures Low Conductivity Media
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Conductivity down to 0.8 µS/cm
Other technologies
Positive displacement
Gear
Oval gear
Piston
Helix
Other technologies
Coriolis Mass Flow
Other technologies
Open Channel Flow
Thermal Mass
Flow Meters for
Measuring Gas
Flows
WHAT IS A THERMAL MASS FLOW
METER?
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It is a Meter that directly measures the Gas
Mass Flow based on the principle of
conductive and convective heat transfer –
MEASURE MASS FLOW RATE OR
TOTALIZE COMMON GASES
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Air (Compressed Air, Blower Air, Blast Furnace Air,
Combustion Air, Plant Air, Make-Up Air)
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Natural Gas Industrial (Plant Usage, SubMetering, Boiler Efficiency, Combustion Control)
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Natural Gas Commercial & Governmental
(Building Automation–Reduce Energy Costs, LEED Credits)
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Digester Gas, Bio Gas, Landfill Gas (EPA
regulations and Carbon Credits)
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Flare Gas (Vent Gas and Upset – Dual Range)
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Other: Propane, Nitrogen, Argon, CO2
Immersion type inferential mass flowmeters utilizing constant
temperature thermal dispersion sensor technology.
Rate of heat absorbed from the sensor by the flowing gas molecules
contacting the sensor is proportional to the gas mass velocity.
Mass flow rate is mass velocity passing through a fixed area.
mass velocity x area = mass flow.
Sensor construction - two ratiometrically-matched, reference-grade
platinum Resistance Temperature Detectors (RTDs) sheathed in 316
stainless steel thermo wells.
Wetted sensors are 316 SS (or optional Hastelloy C276).
•One of the RTDs is self-heated by the
circuitry and serves as the Flow
Sensor
•Second RTD acts as a Reference
Sensor. Used for Temperature
Compensation
continued
Transitions in pipe sizes, old pipes…..
Inline style connections
For line sizes 0.250" to 2.50“
•Pipe thread (MNPT) ends
For 3" lines and greater
•150# class ANSI flanged ends
(optional 300# or 600# class flanges)
Specialty fittings are available . .
•VCRs
•Tri-Clamps
•Electro-polished tube flow sections
for high-purity applications
Insertion style (> line sizes 2.00" )
mounting connections
•Pipe nipples
•Compression fittings
•Flanges
•Ball valve retractor assemblies
•The flowmeter can be inserted into vertical
or horizontal pipes, and at any location
around the pipe diameter.
•Probes are positioned so the RTDs are
located at the Point-of-Average-Flow or
0.243r from the inside insertion wall. (Actual
probe length may be shorter than half the pipe
diameter.)
Inputs
•24 VDC Power (draws less than 100 ma)
•115 VAC/ 230VAC
•12 VDC Optional
Outputs
•4 – 20 ma of Flow Rate
•12 VDC Pulses of Totalized Flow (Solid State,
sourcing, transistor drive – 500ms Pulse)
•Modbus® compliant RS485 Communications
THERMAL MFM ADVANTAGES
(OVER OTHER TYPES OF TECHNOLOGIES)
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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!
Very high gas flow velocities
Compressed Dry Air (CDA) is one of the primary components of overall energy use.
Benefits :
 Monitor general usage for
energy and plant
cost conservation
 Track peak usage to correctly
determine optimum compressor
capacity
Applications -Compressed Air
Facilities Monitoring
 Sub-metering/Billing
 Leak Detection
 Energy Conservation
 Compressor Optimization
 Performance Testing
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52
Accurately tracking the natural gas usage within a facility, whether used for
seasonal heating or for critical production processes . . . . .
Benefits
•Information needed to
adjust for peak usage
•Correctly assign costs
to general operating expenses
For new facilities or for improvements to existing facilities
•Eliminate the undesirable system pressure drops and high maintenance costs
associated with the older technology of differential flow meters and rotary
load meters.
•Example
Compressed Air is needed
to promote optimal bacteria
growth in aeration basins.
Closely controlling the
aeration process can
reduce energy usage
by as much as 25%.
Improving efficiency…..
 Basic fuel costs — by monitoring the fuel-to-air ratio, the most cost-effective mixture for
efficient combustion is better controlled;
 Reduced emissions — efficient combustion helps to avoid fines associated with excess
environmental pollution;
 Lower plant maintenance costs —
efficient combustion reduces the
amount of routine maintenance
associated with this volatile
process;
 Extended equipment life — by
keeping the combustion process
within its optimum design
specifications, the overall system's
operating life is extended.
TECHNOLOGY
SUMMARY
Technologies
Technology
58
Operating
Principle
Advantages
Disadvantages
Fluids Measured
DP
(Differential
Pressure)
Orifice plate
Pitot tube
Variable area
Venturi
V-Cone
Accelabar
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
Liquids
Gases
Steam
Vortex
Inline
Insertion
Bluff body creates
alternating vortices, vortex
shedding frequency equal to
fluid velocity

High accuracy
No moving parts
 No maintenance
 Measures dirty fluids
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
Can be affected by pipe
vibration
 Cannot measure low flows
Liquids
Gases
Steam
Turbine
Inline
Insertion
Dual turbine
Turbine rotates as fluid
passes by, fluid velocity
equal to blade rotational
frequency

High accuracy
Low flow rates
 Good for steam
 Wide turndown
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
Moving parts require higher
maintenance
 Clean fluids only
Liquids
Gases
Steam
Magnetic
Mag
Electromagnetic
Measures voltage generated
by electrically conductive
liquid as it moves through a
magnetic field, induced
voltage is equal to fluid
velocity
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Conductive
liquids
(condensate)

High Accuracy
Wide turndown
 Bi-directional
 No moving parts
 No pressure loss to system
Conductive fluids only
Expensive to use on large
pipes
Technologies Cont’d
Technology
Operating
Principle
Advantages
Disadvantages
Fluids Measured
Transit-time
Ultrasonic
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 spoolpiece)
Doppler
Ultrasonic
Fluid velocity measured by
sensing signals from
reflective materials within the
liquid and measuring the
frequency shift due to the
motion of these reflective
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
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Gases

materials
Thermal
Mass
59
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
??????????????????????
QUESTIONS
AND
ANSWERS
Complete solutions . . .
. . . to all your
instrumentation needs !!!