Flow Sensors

This is a PPT about Flow Sensors.

1. Prepared By : Saralah Alizadeh Arand
Supervisor : Dr B.Rashidian

Sharif University of Technology

1

2. Fluid Basics
Flow Basics
Flow Sensors
Different Types
Principles
Basic Specs
Comparison
Products
Prices
Trends
Conclusions
2

3. What is the Fluid?
Under shear force :
Solid is Elastic
Fluid deforms continusely




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Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

4. Newtonian vs non-Newtonian fluids
Newtonian : In a newtonian fluid shear stress
relates to velocity gradient linearly:




Non-Newtonian : In some fluids like honey
and blood the above equation doesn’t satisfy
4
u: velocity
µ: Dynamic Viscosity
Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

5. Measurement & Units
Compressible & Incompressible
Steady & unsteady flow
Viscous & inviscid flow
General Equations of Flow
Bernoulli’s Equation
No-slip condition & Boundary layer
Reynolds number
Laminar & Turbulent

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Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

6. Flow can be measured in terms of :
Quantity: how many liters of gas did I use and how
much will it cost me?
Liquid : gallons, barrels or liters
Gas : cubic feet (ft3), cubic meters (m3)
Vapour (steam) : lbs, kg
Rate : you must keep the water flowing at 10 gallons
per minute to fill up the pool by lunch time.
Liquid : gallons per minute (gpm) or liters per min.
Gas : cubic feet/hr (ft3/hr), cubic meters/hr (m3/hr)
Vapour (steam) : lbs/hr, kg/hr


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Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

7. For all flows, The Continuty Equation states that:



In an incompressible flow the mass density is constant
Thus divergence of velocity is zero.
If the velocity of the flow is low enough:







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Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

8. A flow is considered to be a compressible flow if the
change in density of the flow is non-zero.
This is the case where the Mach Number in part or all
of the flow exceeds 0.3.
M > 0.3

Mach Number:

M=
8


Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

9. In a Steady flow characteristics of flow
(pressure, velocity, temprature) don’t change
with respect to time.

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Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

10. Flow is essentially viscous, i.e. Friction
between layers is present.
For simplificatin purposes it is ideally assumed
that viscous phenomenon is negligible
(inviscid).
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Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

11. All newtonian Fluids satisfies the “Navier-
Stokes” momentum Equations set
Relates velocity vector with pressure function
in flow domain
3 PDE momentum equations in x,y, and z
directions
Nonlinear without a general Analytical
solution
Analytical solution in special cases By
Simplification assumption
Computational fluid Dynimaics (CFD)
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Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

12. Steady
Incompressible
Inviscid
Between 2 points of a
streamline
Very benefitial in piping
and hydraulics
12 constvhgPorvhgPvhgP 
2
2
12
22
1
22
2
12
1
11

Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

13. At a solid boundary, the fluid will have zero velocity
relative to the boundary.
Bounadary Layer:
Established by Prantel in 1931
Narrow region surrounding the fluid
boundaries
It’s develpoing in flow direction
In Boundary region viscous effects should be considered
Outside of BL flow is inviscid; i.e. Bernoulli Equation is valid

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Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

14. Established by Osborne Reynolds in 1883
Reynolds number is a dimentionless parameter.
Ratio of inertial force to viscous force
Directly exhibits flow speed in same
experiments.
Describe the velocity profile of flowing fluids.
14
In the case of flow through a pipe:
Re < 2000 Laminar
Re > 3000 Turbulent
Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

15. Flow can be considered laminar ,turbulent or a
combination of both.
At low flow rates, fluids have a laminar flow characteristic.




At high flow rate the laminar break up and becomes
turbulent.

15
Laminar
Turbulent
Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

16. The fluid that have contact with constraining
walls will produce zero velocity.
In the center of the flow, the liquid particles
have the maximum velocity
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Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

17. 17
Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

18. Our interest in the measurement of air and
water flow is timeless.
In the Sumerian cities of Ur, Kish, and Mari near the
Tigris and Euphrates Rivers around 5,000 B.C.

Is a critical need in many industrial plants:
It can make the difference between making a profit or
taking a loss.
Inaccurate flow measurements can cause serious (or
even disastrous) results.
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Fluid Basics Flow Basics Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

19. Differential Pressure
Orifice Plate
Venturi Tube
Flow Tube
Flow Nozzle
Pitot Tube
Elbow Tap
Target
Variable-Area(Rotameter)
Open-Channel
Weir
Flume
MFC
Mass
Coriolis
Thermal


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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

20. Velocity
Turbine
Vortex Shedding
Swirl
Conada Effect & Momentum Exchange
Electromagnetic
Ultrasonic, Doppler
Ultrasonic, Transit-Time
Positive Displacement
Reciprocating Piston
Oval Gear
Nutating Disk
Rotary Vane
MEMS
20
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

21. Differential Pressure
MFC
Mass
Velocity
Positive Displacement
MEMS


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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

22. The most common units in use today.
Over 50 percent of all liquid flow measurement
applications use this type
Calculation of fluid flow rate by reading the pressure loss
across a pipe restriction
As a fluid passes through a restriction, it accelerates, and
the energy for this acceleration is obtained from the fluid's
static pressure.
22
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

23. The relationship is determined by the Bernoulli
equation.

23 PKCQ
Q
Q
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PKQ
PP
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Av
PP
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VVAVAQ
dactual
ideal
actual
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21
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12211


K :Constant of flow obstruction device
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

24. Most commonly used flow sensor
An orifice is a flat piece of metal with a specific-
sized hole
Pressure taps on either side of the plate are
used to detect the difference

24
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

25. Have no moving parts
Low cost
Liquids with suspended solids can also be
metered
Low precision
High pressure loss

25
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

26. Consist of a tapered tube and a float
Float have a density higher than that of the fluid

When there is no flow:
The float rests at the bottom of the tube.

As liquid enters :
The float begins to rise.


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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

27. Its position
The point where the differential balance the weight of the float
No secondary flow-reading
devices are necessary
Rotameter tubes are
manufactured from glass,
metal, or plastic.






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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

28. Accurate measurement and control of a mass
flow of gas
 4 main components:
A bypass
A sensor
An electronics board
A regulating valve


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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

29. Measurement side (a Mass Flow Meter):
The bypass
The sensor
One part of the electronics board

Controlling side:
The regulating valve
The other part of the electronics board

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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

30. The sensor can only measure small flow
The bypass :
Control greater amounts of flow
Sensor :
Uses the thermal properties of a gas(specific heat)
Directly measure the mass flow rate
Adds heat to a gas and monitoring
the change in temperature





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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

31. The electronics board:
amplifies and linearizes the sensor signal
compares the sensor’s output to the desired set point
error signal that
A piezoelectric actuator
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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

32. Coriolis
Thermal
32
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

33. Coriolis effect:
Particle (dm) travels at a velocity (V) inside a tube
The tube is rotating about a fixed point
The particle moves with angular velocity (w)
under two components of acceleration
A centripetal acceleration
A coriolis acceleration acting at right angles to a
r

a
t (Coriolis) = 2wv
33
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

34. A force of a
t (dm) has to generated by the tube



If the process fluid has density D and is flowing at
constant speed inside a rotating tube of cross-sectional
area A, a segment of the tube of length x will experience a
Coriolis force of magnitude:

F
c = 2wvDAx
so:
Mass Flow = F
c/(2wx)




34
a
t (Coriolis) = 2wv
F
c = a
t
(dm) = 2wv(dm)
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

35. Rotating a tube is not practical when building a
commercial flowmeter
Oscillating or vibrating the tube can achieve the same
effect.
The tube is anchored at two points and
vibrated between these anchors.

Drivers vibrate the tubes
Drivers consist of a coil connected to
one tube and a magnet connected
to the other




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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

36. When there is no flow:
identical displacements at
the two sensing points



When flow is present:
Coriolis forces act to produce
a secondary twisting vibration
Small phase difference in the
relative motions

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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

37. Include :
Two temperature sensors
An electric heater
1. Introducing a known amount of
heat into the flowing stream and
measuring an associated temperature
change
2. Maintaining a probe at a constant
temperature and measuring the
energy required to do so
The heater can protrude into the fluid
or can be external to the pipe

37
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

38. Velocity
Turbine
Vortex Shedding
Swirl
Conada Effect & Momentum Exchange
Electromagnetic
Ultrasonic, Doppler
Ultrasonic, Transit-Time

38
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

39. Operate linearly with respect to the volume flow
rate
No square-root relationship (as with differential
pressure devices)
Minimum sensitivity to viscosity changes
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Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

40. Invented by Reinhard Woltman in the 18th century
Has found widespread use for accurate liquid
measurement applications
It consists of a multi-bladed rotor mounted at right
angles to the flow
The rotor spins as the liquid
passes through the blades
40
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

41. The rotational speed can be sensed by magnetic
pick-up, photoelectric cell, or gears
The number of electrical pulses counted for a given
period of time is directly proportional to flow
volume.

41
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

42. Make use of a natural phenomenon that occurs when
a liquid flows around a bluff object.
Discovered by Theodor von Karman
Eddies or vortices are shed alternately downstream
of the object
The frequency of the
vortex shedding is
directly proportional
to the velocity of the
liquid
42
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

43. A sensor detect the presence of the vortex and generate
an electrical impulse.
shedding frequency is independent of fluid properties such
as density, viscosity, conductivity, etc.
The relationship between vortex frequency and fluid
velocity is:
St = f(d/V)
St is the Strouhal number

Q = AV = (A f d B)/St
B is the blockage factor

Q = fK
43
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

44. The operation is based on Faraday's law of
electromagnetic induction:
E = BLV
Ideal for any dirty liquid which is conductive.
Ideal for applications where low pressure drop
and low maintenance are required.

44
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

45. Consists of :
A non-magnetic pipe lined with an insulating material.
A pair of magnetic coils
A pair of electrodes penetrates the pipe.
45
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

46. Doppler effect established by Johann Doppler in
1842
The frequencies of received sound waves:
Depended on the motion of the source or observer relative to
the propagating medium.

46
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

47. Transmitted wave hits particles in the liquid and
reflect back.
The velocity of the fluid creates a frequency shift.
47
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

48. Two transducers are
required
It takes less time to go
upstream than downstream
Flow is a function of the
difference in time





48
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

49. Good for clear liquids or gases
Better accuracy than Doppler
Difficult to align
49
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

50. Positive Displacement
Reciprocating Piston
Oval Gear
Nutating Disk
Rotary Vane

50
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

51. High accuracy
Separate liquids into accurately measured
increments
Each segment is counted by a connecting register
Popular for automatic batching and accounting
applications
51
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

52. The most common PD meter
Used as water meter
Function:
Water flows through the metering chamber
It causes a disc to wobble (nutate), turning a spindle,
which rotates a magnet.
The meter housing is
usually made of bronze
52
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

53. Two rotating, oval-shaped gears
A fixed quantity of liquid
passes through the meter
for each revolution
53
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

54. Thermal transfer
Pressure distribution
Based on Drag Force
Based on von Karman Vortex Shedding
Based on Flow Turbine
Artificial Haircell (AHC)
…
54
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

55. An optical MEMS flow sensor based on drag force
 consists of:
A tall, wide cantilever beam or wall hinged at the bottom
Silicon tension spring
Optical fiber
55
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

56. 56
The drag force of fluid force provides a clockwise torque
Result a tilt angle of θ
The deflection of the beam will be sensed by a optical fiber
The light reflects from an Au mirror on the beam back into
the fiber.
 If the beam is deflected, less light
will be reflected back

Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

57.  Relation between fiberoptic intensity loss and
beam offset
57
Relative beam offset theta/theta0
Intensity loss

Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

58. Consists of:
A silicon cantilever beam
(cilium)
Silicon piezo-resistive
strain gauge
58
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

59. Flow passing through the cilium introduces a bending
moment
59
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

60. The resistance of The piezoresist varies under
strain
The output voltage is corresponding to the
strain

60
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

61. 61
We can use an array of AHSs to achieve an
accurate flow measurement.
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

62. Typical Accuracy
In percent of full scale
Pressure loss
Pipe sizes
Flow Rate
Cost
Liquid
Steam
Natural Gas
Fuel Oil
Water
Pressure
Temperature
Viscosity




62
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

63. Which type of flow sensors should be used?
63
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

64. Flowmeter element Recommended Service Range Pressure loss Typical Accuracy, % L (Dia.) Cost
1.Orifice Clean, dirty liquids;
some slurries
4 to 1 Medium ±2 to ±4 of full scale 10 to 30 Low
Venturi tube Clean, dirty and viscous liquids; 4 to 1 Low ±1 of full scale 5 to 20 Medium
Flow nozzle Clean and dirty liquids 4 to 1 Medium ±1 to ±2 of full scale 10 to 30 Medium
Pitot tube Clean liquids 3 to 1 Very low ±3 to ±5 of full scale 20 to 30 Low
Elbow meter Clean, dirty liquids; some slurries 3 to 1 Very low ±5 to ±10 of full scale 30 Low
Variable area Clean, dirty viscous liquids 10 to 1 Medium ±1 to ±10 of full scale None Low
6.Positive Displacement Clean, viscous liquids 10 to 1 High ±0.5 of rate None Medium
3.Turbine Clean, viscous liquids 20 to 1 High ±0.25 of rate 5 to 10 High
7.Vortex CLean, dirty liquids 10 to 1 Medium ±1 of rate 10 to 20 High
4.Electromagnetic Clean, dirty viscous conductive
liquids& slurries
40 to 1 None ±0.5 of rate 5 High
Ultrasonic (Doppler) Dirty, viscous liquids and slurries 10 to 1 None ±5 of full scale 5 to 30 High
Ultrasonic(Travel Time) Clean, viscous liquids 20 to 1 None ±1 to ±5 of full scale 5 to 30 High
5.Mass (Coriolis) Clean, dirty viscous liquids; some
slurries
10 to 1 Low ±0.4 of rate None High
2.Mass (Thermal) Clean, dirty viscous liquids; some
slurries
10 to 1 Low ±1 of full scale None High
Weir (V-notch) Clean, dirty liquids 100 to 1 Very low ±2 to ±5 of full scale None Medium
Flume (Parshall) Clean, dirty liquids 50 to 1 Very low ±2 to ±5 of full scale None Medium
64
Rangeability is the ratio of full span to smallest flow that can be measured with sufficient accuracy.

65. Orifice Plate

65
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
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66. 66
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

67. Vortex
67
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

68. Electromagnetic
68
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
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69. 69
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

70. Wide range of prices
Rotameters are usually the least expensive
For some small-sized units : less than $100
Mass flowmeters cost the most
Prices start at about $3500
Installation, operation, and maintenance costs
are important economic factors

70
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

71. 71





FDT103
Ultrasonic Flowmeter
Omega Engineering
$2,120.00



FMG-403H-T
Magnetic Flow meter
Omega Engineering

$2,600.00






M100L
MASS FLOW METER
Davis Instruments
$1,150.00
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

72. 72
810C-DR
MFC
Davis Instruments

$1,045.00


VORTEX
5755 SCFH
VORTEX FLOWMETER
Cole-Parmer Instrument
$2,390.00


OVAL GEAR



GM007R2R21
OVAL GEAR
Davis Instruments

$1,257.00






P16B4-BA0A
ROTAMETER
Davis Instruments
$136.00
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

73. 73
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

74. There is a trend in:
Ultrasonic
Magnetic
Mass
MEMs
 …
74
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

75. Over 75 percent of the flowmeters installed in
industry are not performing satisfactorily
Improper selection accounts for 90 percent of these
problems
Flowmeter selection is no job for amateurs!
What is the instrument supposed to do?
75
Fluid Basics Flow Basic Flow Sensors Different Types Principles Basic Specs
Comparison Products Prices Trends Conclusions

76. 76