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Theory: Terms & DefinitionsTheory: Terms & Definitions
ULTRASOUND
Frequency (f ):
Subsonic 0 to 20 Hz
Audio 20 Hz to 20 kHz
Ultrasonic >20 kHz
f cyclessecond
=
λ proportional to 1f
λ
Theory: Terms & DefinitionsTheory: Terms & Definitions
ULTRASOUND
Materials (different materials support different frequencies):
Solids 1 MHz to 100 MHz
Liquids .25 MHz to 5 MHz
Gases 20 kHz to 200 kHzFr
eque
ncy,
f
Density, ρ
Theory: Terms & DefinitionsTheory: Terms & Definitions
SPEED OF SOUND (c)
How Fast a Sound Wave Moves Through a Given Medium
Property of a Material
c = f (Temperature)
c ≠ f (Frequency)
Gases
H2OLiquids
Temperature, °C
c
74
Density, ρ
c
Speed of Sound Examples:
SS = 6500 m/s
H2O = 1500 m/s
Air = 330 m/s
@ 25°C
Theory: Terms & DefinitionsTheory: Terms & Definitions
Atte
nuat
ion
Distance
f (material)ATTENUATION
Reduction in Amplitude of the Ultrasonic Signal• Dissipation
• Reflection
• Absorption
ATTEN = 1/GAIN
How Loud? More Attenuative
Less Attenuative
MOLECULAR LEVEL
Theory: Terms & DefinitionsTheory: Terms & Definitions
TRANSDUCER
Electrical Energy Mechanical Energy
Mechanical Energy Electrical Energy
Piezoelectric Effect
Transducer is Both Transmitter and Receiver
V V V
V V V
TRANSMIT
RECEIVE:
Theory: Doppler TechniqueTheory: Doppler Technique
DOPPLER PRINCIPLE
When sound of a given frequency reflects off a moving object, the reflected frequency is shifted in proportion to the velocity of the moving object.
XMITRCV
V
θ
Theory: Doppler TechniqueTheory: Doppler Technique
PROBLEMS
Scatterer Size
Scatterer Reflectability
Scatterer Velocity ≠Fluid Velocity
Clean Fluids
~10% Accuracy
V = (F F ) c2F COS
T R
T
−θ
V = Scatterer Velocity
FT = Transmitted Frequency
FR = Received Frequency
θ = Angle of Sound Beamwith Respect to Flow Axis
c = Sound Speed of the Fluid
Theory: Transit Time TechniqueTheory: Transit Time Technique
Transducer is Both Transmitter and Receiver
Ultrasonic Pulses
Transit Times
Upstream direction, tup
Downstream direction, tdn
tup = Ultrasound is Decelerated by Flow
tdn = Ultrasound is Accelerated by Flow
Analogous to a Flowing River
t t
t t t
V f( t)
Q V A
up dn
up dn
>
= −
=
= ×
∆
∆
UP
DOWN
V
Theory: Transit Time TechniqueTheory: Transit Time Technique
V = Fluid Velocityc = Fluid Sound Speedtup = Transit Time in the
Upstream Directiontdn = Transit time in the
Downstream Direction∆ t = Transit Time DifferenceP = Acoustic Path Through FluidL = Axially Projected Path
Through Fluidθ = Path Angle
DN
UP
V
LPθ
Theory: Transit Time TechniqueTheory: Transit Time Technique
NO FLOW
DISTANCE RATE TIME
TIME DISTANCERATE
= ×
=
t Pc
t Pc
t t t 0
up
dn
up dn
=
=
= − =∆
WITH FLOW
t Pc -Vsin
t Pc+ Vsin
t t t
up
dn
up dn
=
=
= −
θ
θ
∆
V
V
θθ
θθ
c
c
DN
UP
Vθ
LP
Theory: Transit Time TechniqueTheory: Transit Time Technique 1
t c - sin
P 1
t c + Vsin
P
t t
t
c + VsinP
- c - VsinP
t
t = 2Vsin
P
V Psin
t
t
.
Since sin LP
.
V PL
t
t
.
up dn
dn up
up dn
dn up
dn up
= =
= − =
−
= −
=
= −
θ θ
θ θ
θ
&
∆1 1
1 1
21 1
21 12
θ
θ
Theory: Transit Time TechniqueTheory: Transit Time TechniqueVELOCITY
V P2L
t tt t
2 up dn
dn up=
−
×
SOUND SPEED
tt t
2
c = Pt
avg = dn up
avg
+
Q = Velocity × Cross-Sectional Area
Q = V × A
VOLUMETRIC
Theory: Transit Time TechniqueTheory: Transit Time Technique
CLAMP-ON
Refraction
Snell’s Law
Built-In Correction for Liquid Property Changes
csin
csin
csin
1
1
2
2
3
3θ θ θ= =
c1
θ1c2θ2
θ3c3
L
S
W.T.
c1 = Wedge Sound Speedc2 = Wall Sound Speedc3 = Fluid Sound SpeedS = Transducer Spacing
Theory: Fluid DynamicsTheory: Fluid Dynamics
FLOW PROFILEThe Shape of the Flow Due to Friction and Viscous Forces in the Pipe
REYNOLDS #The Measure of the Shape of the Flow Profile
Re = Reynolds #
V = Fluid velocity
ID = Pipe ID
ν = Kinematic viscosity
(ft2/sec or m2/sec)
Re =×V IDν
ν absolute viscosityfluid density
=
Theory: Fluid DynamicsTheory: Fluid Dynamics
FLOW PROFILE REGIONSLaminar:
• Stratified, parabolic profileRe = 0 to 2000
Transitional:
• Undefined profileRe = 2000 to 4000
Turbulent:
• Flattened profileRe = >4000
Theory: Fluid DynamicsTheory: Fluid Dynamics
FLOW PROFILE FACTOR (kRe)
Diametrical Interrogations
Theoretical Correction Factor
Based on Re
Nikuratze’s Equation
V = kRe × Velocity
Ranges:
laminar = 0.75transitional ≈ 0.85turbulent = 0.91 - 0.99
NOTE: A 10:1 change in v results in <1% change in flow.
Example: V = 5 ft/sec and ID = 6”v = 10×10-6 v = 100×10-6
Re = 250,000 Re = 25,000kRe = 0.944 kRe = 0.934
k = 11.119 0.011 log ReRe −
Theory: Fluid DynamicsTheory: Fluid DynamicsSTRAIGHT-RUN REQUIREMENTS
Fully Developed Flow Profile
10 Upstream/5 Downstream dia.
Disturbances
• bends
• valves
• wells
• tees
• insertions
10∅ 5∅
Theory: Fluid DynamicsTheory: Fluid Dynamics
STRAIGHT-RUN REQUIREMENTSHorizontal Flowing Up
Vertical Flowing Up
What if I Don’t Have 15 Diameters?• 2/3 up, 1/3 down• multipath• flow straighteners• accuracy cannot
be quantified• repeatability
10∅ 5∅
Liquid Flow: DiagnosticsLiquid Flow: Diagnostics
SIGNAL STRENGTH (SSup, SSdn)
Amplitude of the Received Signals
Liquid Flow: DiagnosticsLiquid Flow: Diagnostics
SOUND SPEED (SNDSP)
Measured “c”
Independent of Programmed “c”
“The More Accurate the Measured Sound Speed Value, the More Accurate the Flow Reading”
Tables In Manuals
c Pt
tT T
2
avg
avgup dn
=
=+
Liquid Flow: DiagnosticsLiquid Flow: Diagnostics
SIGNAL QUALITY (Qup, Qdn)
Shape of Received Signal
Coded Transmits
Q > |300|
Pipes < 4”, Q > |180|
• 4-Bit Code
TRANSMIT
RECEIVE
Liquid Flow: DiagnosticsLiquid Flow: Diagnostics
SIGNAL PEAKS (Pup, Pdn)
Window Position
Programmed “c”
“500,” Centered Signal
<100, No Signal
>900, No Signal
Tracking Window10000
t = P/c
Liquid Flow: Signal ProcessingLiquid Flow: Signal Processing
“WINDOW POSITIONING”
Based on Programmed Sound Speed
• Time =
• +20%
Reduces ProcessorTime
Avoids Short Circuit
DistanceRate
“c”
t = 0
TRANSMITCODEDSIGNAL
SHORTCIRCUIT
RECEIVED SIGNAL
“c”
WINDOW
Liquid Flow: Signal ProcessingLiquid Flow: Signal Processing
CODED SIGNALS
BAD CORRELATION
GOOD CORRELATION
≈∆t
tdn
tup
CORRELATION
Signal Quality
Liquid Flow: Signal ProcessingLiquid Flow: Signal Processing
∆t MEASUREMENT
Cross Correlation
More Accurate
1 Nanosecond Resolution
CORRELATION tdn
CORRELATION tup
∆t
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
FULL PIPES ONLY
Accuracy
Signal Loss
Q = V × A
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
Bubbles to top
ENDVIEW
TOPVIEW
Sediment to bottom
L
L/2
SINGLE PHASE OR MULTIPHASE
Mount the Transducers on the Sides of the Pipe
3 O’Clock / 9 O’ClockPosition
Single vs Double Traverse
Transducer Frequency
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
PIPE CONDITION
Clean Outside Surface!
• Rust/PaintCouplant
• Good contactInside Build Up
• Attenuation• Transducer frequency• Accuracy
Single vs. Double Traverse
VS IDID
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
PIPE SIZE
Overall Range: 1/2” to 200” (12 mm to 5 m)
Transducer Selection• 1/2” to 2” • 2” to 200”
Clamping Fixture Selection
Transducer Frequency
• 0.5 MHz for large pipes
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
PIPE MATERIAL
Metals• Carbon Steel• Stainless Steel• Copper• Aluminum • Cast Iron• Brass• Ductile Iron
WT
c2
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
PIPE MATERIALPlastics• PVC• Polypropylene• Polyethylene• CPVC• PVDF• Nylon• Acryllic
WT
c2
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
PIPE MATERIAL
Wall Thickness
Sound Speed (C2)
Liners
Concrete No Clamp-On
WT
c2
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
VELOCITY EXPECTED
Good: V > 1.0 ft/s (0.3 m/s)
Minimum Detectable Velocity
• V = 0.1 ft/s (0.03 m/s)• Accuracy
Maximum: V < 40 ft/s (12m/s)
Resolution of ∆t
• Higher velocity = more ∆t
Slide Rule
EQUATIONSArea =
Q = V × A
USEFUL CONVERSIONS
1 Gallon = 0.13368 ft3
1 Barrel = 42 gallons
1 Liter = 0.001 m3
π ID2
2
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
vsTEMPERATURE
Transducer Type
Clamp-On
•Couplant type•Couplantmaintenance
vs
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
PIPING ORIENTATION
Horizontal = Good
Vertical Flowing Up = Good• Ensures full pipe
Vertical Flowing Down = Less Desirable
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
STRAIGHT-RUN REQUIREMENTSFully Developed Flow Profile10 Upstream/5 Downstream DiameterDisturbances
• Bends
• Valves
• Wells
• Tees
• Insertions
10∅ 5∅
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
STRAIGHT-RUN REQUIREMENTSHorizontal/Vertical Flowing Up
What If I Don’t Have 15 Diameters?
• 2/3 up, 1/3 down
• Multipath
• Flow straighteners
• Accuracy cannot be quantified
• Repeatability
10∅ 5∅
Liquid Flow: Application Liquid Flow: Application ConsiderationsConsiderations
VISCOSITY
Maximum ~300 centistokes
Attenuation
Low Reynolds Number
Atte
nuat
ion
Viscosity300
less
more
Liquid Systems: ComponentsLiquid Systems: Components
Electronics
CouplantClampingFixture
Cable
Transducers
CLAMP-ONElectronics
• Portable
• Dedicated
• Transmitter
Transducers
Clamping Fixture
Cable
Couplant
Liquid Systems: ClampLiquid Systems: Clamp--on on TransducersTransducers
TRANSDUCER #
Liquid Systems: ClampLiquid Systems: Clamp--on on TransducersTransducers
SMALL PIPES
ADJUSTABLE FIXED
VELCRO/SSSTRAPS
Liquid Systems: Clamping FixturesLiquid Systems: Clamping Fixtures
SINGLETRAVERSE
DOUBLETRAVERSE
LARGER PIPES
Liquid Systems: Clamping FixturesLiquid Systems: Clamping Fixtures
BLOCK STYLE (CF-BL)
Permanent Installations
Stainless Steel Straps
“Hose Clamp” Tightening Mechanism
Must Specify Pipe Size
Liquid Systems: Clamping FixturesLiquid Systems: Clamping Fixtures
DOUBLE TRAVERSE
SINGLE TRAVERSE
MAGNETIC (MC)
Cabon Steel Pipes ONLY!
Liquid Systems: ComponentsLiquid Systems: Components
CABLE
TRANSDUCERS
FLOWCELL
ELECTRONICS
WETTED
Flowcell
• Spoolpiece• Pipe couplings• Saddles
Cable
Liquid Systems:Wetted Liquid Systems:Wetted TransducersTransducers
STANDARD VERSION
1” NPT
Liquid Systems:Wetted Liquid Systems:Wetted TransducersTransducers
EXTENDED WELL DESIGN
Liquid Systems: TransducersLiquid Systems: Transducers
ADAPTER
Hybrid System• Removal of transducers
NOTE: WT-1/P TRANSDUCERS WITHOUT EXTENDED WELL ARE USED
Liquid Systems: Liquid Systems: FlowcellsFlowcells
SPOOL PIECES
Process Connection• Plain ends (welding)
• Flanged ends
Transducer Connection• 1” NPT
• Socket weld/Panadapta
PLAIN END
FLANGED END
Liquid Systems: Liquid Systems: FlowcellsFlowcells
PIPE COUPLINGS (PC)Weld Distortion
Pipe Coupling Kit• Single traverse
1" NPT
WELDS = OD
WELD
Liquid Systems: Liquid Systems: FlowcellsFlowcells
SADDLESWelding Not Possible• Ductile iron
• Cast iron
• Concrete
1” NPT
Liquid FlowmeterLiquid Flowmeter
REASONS FOR USING ULTRASONICWide Range of Pipe Sizes, 1/2” to 200”
Turn-Down Ratio
Pressure Drop
Bi-Directional Flow
Maintenance
No Moving Parts
“Clamp-On” Independent of Pipe Size (Cost)
Liquid FlowmeterLiquid Flowmeter
REASONS FOR USING ULTRASONIC
Corrosive Fluids
High-Temperature Fluids
Radioactive Fluids
Purity
Multichannel Capability
Cost of Installation
Liquid FlowmeterLiquid FlowmeterTYPICAL APPLICATIONS
AcidsCorrosive, Erosive& Toxic LiquidsChemicalsCryogenics• LPG• LNG• Argon
Petroleum Products
• Benzene Propane
• Ethylene Crude Oil
• Solvents Fuels
• Lube Oil Xylene
Water
Waste Water
Seawater
Liquid FlowmeterLiquid Flowmeter
TYPICAL USESBalancing Systems
Batching
Billing/Accounting
Check Metering
Heating/Cooling
Efficiency Studies
Flow Surveys
Leak/Rupture Detection
Process Control
Large/Small Pipes
Liquid FlowmeterLiquid Flowmeter
INDUSTRYPetrochemical
• Refining• Chemical processing• Process control
Power
• Fossil fuel• Nuclear• Hydroelectric
Food & Beverage
Energy Management• Hot water• Chilled water
Manufacturing
Medical
Liquid FlowmeterLiquid Flowmeter
INDUSTRY
Pharmaceutical
Pulp & Paper
Semiconductor Manufacturing• Ultra-pure liquids
• Deionized water
Sewage Treatment
Water & Waste Water Management
Aerospace
Agriculture
Gas Flow MeasurementGas Flow Measurement
DIFFERENCES FROM LIQUID
No Clamp-On!
Slower Sound speeds
• Longer transit times
Greater Attenuation
• Lower frequencies
• 30 to 500 kHz
UP
DOWN
V
Gas Flow MeasurementGas Flow MeasurementEQUATIONS
Standard Flow• Gases are compressible• Pressure• Temperature
Standard Conditions• Base pressure = 1 atm (14.7 psia)• Base temperature = 20 C → 293 K
= 68 F → 528RVelocity• Calculate VACT
*The velocity the transducers are exposed to.
Q Q PP
TT
Q V AREA
STD ACTf
b
b
f
ACT ACT
= × ×
= ×
→
NOTE: MUST USE ABSOLUTE PRESSURE & TEMPERATURES IN CALCULATIONS.
Gas Flow MeasurementGas Flow Measurement
EQUATIONS
Mass Flow• kg/hr
• lb/hr
Density• Constant
• Derived MW
M = Mass Flow
V = Actual Velocity
A = Cross-Sectional Area
ρ = Density
P = Pressure (Absolute)
T = Temperature (Absolute)
R = Universal Gas Constant
MW = Molecular Weight
ρ P ( M W )R (T)
=
.M VA= ρ.
Short-Circuit Signal
Some sound energy
shears off through the surface of the pipe
Emitting Transducer
Receiving Transducer
The short-circuit signal travels very quickly to the receiving transducer since it is traveling through a solid – the pipe wall
The sound refracts
through the pipe wall
Emitting Transducer
Receiving Transducer
The sound travels
through the gas
Emitting Transducer
Receiving Transducer
The sound refracts through the other
wall
…and is received by
the downstream transducer
Emitting Transducer
Receiving Transducer
The correct receive signal is the one that travels through the flow – not through the pipe wall
Emitting Transducer
When the sound hits the inside pipe wall, a lot of the signal reflects back into the pipe
This is due mainly to the mismatch in soundspeedsfor the solid wall versus the gas flowing in the pipe
Steel Pipe
Emitting Transducer
The amount of sound strength energy traveling through the gas is only 0.007%0.007% of what was transmitted
Steel Pipe
Emitting Transducer
There is another reflection point when the sound hits the other side of the pipe’s inside wall
Steel Pipe
Emitting Transducer
Here, again, a lot of the signal strength is lost
Steel Pipe
Emitting Transducer
The remaining sound energy that gets to the receiving transducer is only 0.00000049%0.00000049% of that transmitted!
Steel Pipe
t0
POOR SNR (SIGNAL TO NOISE RATIO)
MAKES SIGNAL DETECTION TOO DIFFICULT
New InnovationsNew InnovationsPrimary Innovation
New Transducer Technology :
• SNR
• Increase Signal
• Reduce Noise
New InnovationsNew Innovations
t0
REDUCE NOISE INCREASE SIGNAL
New Innovations: More SignalNew Innovations: More SignalPrimary Innovation
New Transducer Technology : • More signal output with
same applied excitation voltage.
• 5-10x More Signal Amplitude than traditional xducers
• Low Mode Conversion• Highly Efficient
Think of transducer as ‘turbo-charged’
New Innovations: More SignalNew Innovations: More SignalPrimary Innovation
New Transducer Technology :
• Cleaner Signal Shape
• Less Ringing
• Less Prone to Cycle Skipping
• Larger Receive Area
New Innovations: More SignalNew Innovations: More SignalInnovation
More Attention Paid to Alignment
• Clamping Fixture System–Axially–Circumference
• Less Attenuation
• Precise Installation
New Innovations: Less NoiseNew Innovations: Less NoiseInnovation
Less Noise
Short Circuit Dampening
• Dampening Material
• Attenuates Surface Waves
• Attenuates Short Circuit
Application Considerations
Straight RunMinimum requirements:
• 20D upstream• 10D downstream• More is Better
20∅ 10∅
Application ConsiderationsApplication Considerations
FLOW
-1.0 -0.8 -0.6 -0.4 -0.2 -0.0 0.2 0.4 0.6 0.8 1.0
Normalized Horizontal Position (X)
-1.0
-0.8
-0.6
-0.4
-0.2
-0.0
0.2
0.4
0.6
0.8
1.0
Nor
mal
ized
Ver
tical
Pos
ition
(Y)
0.900
0.9
28
0.956
0.956
0.9
83
0.983
0.983
0.983
1.011
1.039
-1.0 -0.8 -0.6 -0.4 -0.2 -0.0 0.2 0.4 0.6 0.8 1.0
Normalized Horizontal Position (X)
-1.0
-0.8
-0.6
-0.4
-0.2
-0.0
0.2
0.4
0.6
0.8
1.0
Nor
mal
ized
Ver
tical
Pos
ition
(Y)
0.900
0.900
0.900
0.9
00 0
.928
0.956
0.983
1.011
1.039
1.06
7
1.094 1.122 10D100D
Application Considerations
Straight RunThe more straight run, the better!
This is a VERY GOOD
installation
Presentation Facilitated by
Insertech (Caribbean) Limited in conjunction with Panametrics