micro-project on different types of flow measuring devices

all types of flow measuring devices are content in the pdf

1. DIFFERENT TYPES OF FLOW MEASURING DEVICES


0 SYP Aurangabad





INDEX

Sr. No Content Page No

01 Introduction 1
02 Types of Flow Measuring Devices 2
03 Rotameter 3
04 Anemometer 6
05 Coriolis Flowmeter 10
06 Oscillating Piston Flow Meter 13
07 Rotary Vane Flow Meter 15
08 Ultrasonic Flow Meter 17
09 Flow Nozzle 21
10 Venturi-meter

23
11 Conclusion

26

2. DIFFERENT TYPES OF FLOW MEASURING DEVICES


1 SYP Aurangabad

INTRODUCTION

1) In many situations, measurement of fluid flow is required, such as in domestic water
supply, water flowing in a canal, air flow to an I.C. engine, petrol delivered to an
automobile, blood flow in human body, besides the industries and laboratory needs.

2) The flowing medium can be

1. Liquid

2. Gas

3. Granular solids, ex (slurry).

3) Accurate measurement of flow rate of liquids and gases is an essential requirement
for maintaining the quality of industrial processes. In fact, most of the industrial
control loops control the flow rates of incoming liquids or gases in order to achieve
the control objective. As a result, accurate measurement of flow rate is very
important.

4) Needless to say, that there could be diverse requirements of flow measurement,
depending upon the situation. It could be volumetric or mass flow rate, the medium
could be gas or liquid, the measurement could be intrusive or nonintrusive, and so on.
As a result, there are different types of flow measuring techniques that are used in
industries.

3. DIFFERENT TYPES OF FLOW MEASURING DEVICES


2 SYP Aurangabad

1. TYPES OF FLOW MEASURING DEVICES

1) Rotameter.
2) Anemometer.
3) Coriolis Flowmeter.
4) Oscillating piston flow meter.
5) Rotary Vane Flow Meter.
6) Ultrasonic Flow Meter.
7) Flow Nozzle.
8) Venturi-meter.

4. DIFFERENT TYPES OF FLOW MEASURING DEVICES


3 SYP Aurangabad


1) ROTAMETER:

I. Construction:

1) The rotameter consists essentially of tapered metering glass tube, inside of
float is located which is active element of meter.

2) The float material has specific gravity higher than that of the fluid to be
metered.
3) The spherical slots cut on a part of the float cause it to rotate slowly about axis
of the tube and keep it center.

4) The stability of the float is ensured by employing a guide along whom the
float would slide




II. Working:


1) With an increase in the flow rate, the float rises in the tube and there occurs in
the annular area between the float and the tube.

5. DIFFERENT TYPES OF FLOW MEASURING DEVICES


4 SYP Aurangabad

2) The float adjusts its position in relation to the discharge through the passes the
float higher or lower depending on the flow rate of the fluid.



Fig. 01: ROTAMETER

3) Rotameter are widely used for metering purge flows, pump-seal fluid and
coolant and lubricants for operating machinery.

6. DIFFERENT TYPES OF FLOW MEASURING DEVICES


5 SYP Aurangabad

III. Advantages:

1) Low cost, direct indicating, minimum piping required.

2) Pressure loss in rotameter is nearly constant and small.

3) It can handle any corrosive fluid.

4) It has quite good accuracy especially at low flow rates.

5) It provides linear scale.
6) Condition of flow is readily visible.


IV. Limitations:

1) It must be installed in vertical position only.

2) For high pressure and temperature, it is expensive.

3) When opaque fluid is used, float may not be visible.

4) It can not be used with liquid carrying large percentage of solids in
suspensions.

7. DIFFERENT TYPES OF FLOW MEASURING DEVICES


6 SYP Aurangabad


2) ANEMOMETER:

1) An anemometer usually measures mean and fluctuating velocities in fluid flows
that are in turbulent flow condition.

2) An anemometer measures the speed or velocity of gases either in a contained
flow.

3) The anemometer works on the basis of convective heat transfer from a heated
sensor to the surrounding fluid, the heat transfer being primarily related to the
fluid velocity.

4) By using very fine wire sensors placed in the fluid and electronics with servo-
loop technique, it is possible to measured velocity fluctuations of fine scale and
of high frequencies.

I. HOT WIRE ANEMOMETER:

1) Hot wire anemometer is used for measurement of flow rate of fluctuating and
unsteady flow.

2) A sensor of 5micron diameter platinum tungsten wire welded between two
prongs of the probe and heated electrically to form part of a wheat-stone
bridge circuit.

3) When the probe is introduced into the flowing fluid it tends to be cooled by
the velocity and there is decreased in its resistance.

8. DIFFERENT TYPES OF FLOW MEASURING DEVICES


7 SYP Aurangabad

4) The rate of cooling of wire depends upon the:

I. Dimensions and physical properties of the wire.

II. Difference of the temperature between the wire and fluid.
III. Physical properties of the fluid.

IV. Stream velocity under measurement.

II. There are two types:

1) Constant current mode.

2) Constant temperature mode.


1) CONSTANT CURRENT MODE:

I. The voltage across the bridge is kept constant.


Fig. 2.1: CONSTANT CURRENT MODE

9. DIFFERENT TYPES OF FLOW MEASURING DEVICES


8 SYP Aurangabad

II. Initially the circuit is adjusted at zero galvanometer reading when the
heated wire lies in still air.

III. When the fluid flows the hot wire cools the resistance changes and the
galvanometer deflects.

IV. The galvanometer deflections are amplified measured and correlated with
fluid velocity by previous calibration.


2) CONSTANT TEMPERATURE MODE:

I. In this type resistance of the wire and its temperature is maintain constant.


Fig. 2.2: CONSTANT TEMPERATURE MODE

10. DIFFERENT TYPES OF FLOW MEASURING DEVICES


9 SYP Aurangabad

II. The interior of the anemometer is an exposed hot wire maintained at a
constant of the velocity.

III. Advantages:

1) For measurement of steady velocity of the constant temperature type is often
used.

2) Main application of hot wire anemometer is for measurement of rapidly
fluctuating velocity.

3) Majority of application is in gas flow meters.



IV. Disadvantages:

1) Fine wire has limited physical strength.

2) Due to dirt accumulation calibration of instrument changes.

11. DIFFERENT TYPES OF FLOW MEASURING DEVICES


10 SYP Aurangabad

3) CORIOLIS FLOWMWTER :

1. The Coriolis flowmeter is primarily used to measured the mass flow rate of
liquids, and in some cases gas flow measurements.

2. The construction of Coriolis flow meter is shown in above figure number 03.


Fig. 03: CORIOLLIS FLOWMETER

3. It consists of either a pair of parallel vibrating tubes or else a single vibrating
tubes that is formed into a configuration that has two parallel sections.

12. DIFFERENT TYPES OF FLOW MEASURING DEVICES


11 SYP Aurangabad

1) Principle of Working:

i. A Coriolis flowmeter requires force acting on a tube carrying a flowing
fluid. This force actually deforms tubes through which the fluid flows.

ii. The amount of deformation depends directly on the mass flow rate through
the tubes.


2) Construction and Working:

i. Tubes are made of various materials of which stainless steel is the most
common.

ii. They are available in different shapes such as B-shape, D-shape, U-shape.

iii. The fig.03 shows U-shape tube in more details.

iv. The tubes are anchored at two points. The electromechanical drive units
between the two anchors excited vibrations in each tube at the tube resonant
frequency.

v. In the tube, the fluid moves away from and back towards the axis of
oscillation, resulting in a changing angular momentum of the fluid

vi. The tubes oscillation result into two opposite forces which twist the tube.
First one way then the other with each oscillation of the fluid.

13. DIFFERENT TYPES OF FLOW MEASURING DEVICES


12 SYP Aurangabad

vii. The output from pickup sensor are sine waves showing oscillation
frequency. Measuring the magnitude of deformation, the mass flow rate can
be measured.


3) Advantages of Coriolis Flow Meter:

i. Its measuring principle is independent of fluids pressure, density, and
viscosity.

ii. Its measurement is independent on Reynolds number.

iii. Its measurement also independent on upstream and downstream flow
velocities.

iv. The meter has high accuracy and high reliability.


4) Disadvantages of Coriolis Flow Meter:

i. Pipe line size is limited and available to the pipe size of 150mm only.

ii. Initial cost is high.

14. DIFFERENT TYPES OF FLOW MEASURING DEVICES


13 SYP Aurangabad


4) OSCILLATING PISTON FLOW METER:

1) Construction and Working:

i. It is one of the oldest types of positive displacement meter. The oscillating
piston flow meter is shown in the below figure number. 04


Fig. 04: OSCILLATING PISTON FLOW METER

ii. it consists of a precious machined slotted cylinder that separate inlet and
outlet part, and a cylinder piston. Motion of the piston is oscillatory since it
is constrained to move in one plane.

iii. The central piston constrained to move in a circular grove eccentrically.

15. DIFFERENT TYPES OF FLOW MEASURING DEVICES


14 SYP Aurangabad

iv. Liquid enters in a cylinder containing an oscillating piston. Liquid pressure
drives the piston to oscillate and rotate on its center hub.
v. As it does so, a specific volume of fluid is mo0ved through the matter. A
sensing system typical magnetic or optical sense the pulse each time a part of
oscillation occurs.
vi. Each revolution of piston hub is equivalent to a fixed volume of fluid. Which
is indicated as flow by an indicator. This motor is essential for viscous fluid.

2) Advantages:

i. It is simple in construction.

ii. It is easy for installation and maintenance.

iii. At low flow rates, it gives good accuracy.

iv. This are highly accurate meters and are ideal for diary, food chemical and
other sanitary application.



3) Disadvantages:

i. It can be used for liquids only that too clean liquids as the meter may
blocked due to suspended large particles in the liquid.

ii. It is relatively expensive, large and heavier than other meters using different
technology

16. DIFFERENT TYPES OF FLOW MEASURING DEVICES


15 SYP Aurangabad

5) ROTARY VANE FLOW METER:
1) Construction and working:

i. Rotary vane flow meter is another type of positive displacement flowmeter.

ii. A rotating vane flowmeter is a type of positive displacement meter in which
the fluid passed through a rotating set of vanes.


iii. The passage between each set of vanes delivers a specific volume of a fluid
to outlet side of the meter, allowing the flow rate to be determined which is
based on revolution of a piston.

iv. At any instance, there is one vane in the stream at any one time, in which
case the rate of revolution of the vane is proportional to the mean flow
velocity.

Fig.05: Rotary Vane Flowmeter

17. DIFFERENT TYPES OF FLOW MEASURING DEVICES


16 SYP Aurangabad

2) Advantages:

i. It gives precise measurement over a wide range of flow.

ii. It has precise and high pressure and temperature ratings.

iii. It has a smaller pressure loss.

iv. Rotary meters are used as domestic water meters and also in hot water
system.



3) Disadvantages:

i. It is suitable for clean liquids.

ii. It is subjected to wear and tear.

18. DIFFERENT TYPES OF FLOW MEASURING DEVICES


17 SYP Aurangabad

6) ULTRASONIC FLOW METER:

A. There are two types of ultrasonic flow meters:

1. Doppler ultrasonic flow meter.

2. Transit time ultrasonic flow meter.

1) Doppler Ultrasonic Flow Meter:

I. Construction and Working:

1. The transducers use the doppler frequency shift of ultrasonic signals
reflected from continuities in the fluid stream to obtain flow
measurement.

2. This discontinuous can be suspended solids, bubbles, or interfaces
generated by turbulent eddies in the flow stream.

3. The sensor is mounted on the outside of the pipe, and an ultrasonic beam
from a piezoelectric crystal is transmitte through the pipe wall into the
fluid at an angle of the flow stream.

4. Signals reflected off flow disturbances are deflected by a second
piezoelectric crystal located in the same pipe at distance L.

5. Transmitted and reflected signals are compared in an electrical circuit,
and the corresponding frequency shift is proportional to the flow velocity.

19. DIFFERENT TYPES OF FLOW MEASURING DEVICES


18 SYP Aurangabad



Fig.6.1: Doppler Flow Meter

6. The basic principle of operation of doppler ultrasonic flow meter is shown
in the above figure number.05.


2) Transmit Time Ultrasonic Flow Meter:

I. Construction and Working:

1. Ultrasonic flow meters are based on the apparent change in the velocity of
propagation of sound waves in a fluid with the change in the velocity of
flow of the fluid.

2. they measure flow velocity of fluid by sending pulses of ultrasound signal
back and forth between two piezoelectric sensors these are upstream
sensors and downstream sensors.

20. DIFFERENT TYPES OF FLOW MEASURING DEVICES


19 SYP Aurangabad

3. The figure of transit time ultrasonic flow meter is shown in the below
figure number.06
4. The microprocessor generates the pulses and measured the elapsed time
required for sound to travel between the piezoelectric sensor.

Fig.6.2: Transit Time Ultrasonic Flow Meter

5. Liquid velocity is proportional to the difference in the time between
upstream and downstream.




II. Advantages:

1. They show minor obstruction to the flow of fluid.

2. Ultrasonic flow meter cannot obstruct flow so they can be applied to
sanitary, corrosive and abrasive liquids.

3. They provide good accuracy of the order of +or – 2 % of the fully scale
deflection.

21. DIFFERENT TYPES OF FLOW MEASURING DEVICES


20 SYP Aurangabad


4. Non-invasive, no moving parts, no wear

5. Ultrasonic flow meters are available in the sizes to 2m and larger.




III. Disadvantages:

i. Its measuring accuracy can be affected by installation and
environment.

ii. For better results, pipe walls need to be clean and free from dirt.

iii. Relatively higher cost compared with other pipes flow meter.

iv. It needs expert to repair and maintain the flow meters.



IV. Applications:

i. In liquid processing application.

ii. For district processing application.

iii. High pressure and high temperature liquids.

iv. Measurement of flow of highly aggressive fluids under high pressure.

22. DIFFERENT TYPES OF FLOW MEASURING DEVICES


21 SYP Aurangabad

7) FLOW NOZZLE:

1. Construction and Working:

i. A compromise between orifice plate and venturi-tube is flow nozzle.

ii. The flow nozzle consists of a smooth, gradual contraction to throat followed
by a free, uncontrolled expansion back to the original flow area.


Fig.07: Flow Nozzle

iii. The flow nozzle consists of convergent inlet and cylindrical throat as shown
in the above figure.

iv. The flow nozzles are usually made of gun metal, stainless steel or mon metal

23. DIFFERENT TYPES OF FLOW MEASURING DEVICES


22 SYP Aurangabad

II. Advantages:
i. Cheaper than standard venturi-meter and can be installed without much
difficult in existing main pipe.

ii. Coefficient of discharge is high as compared to orifice.
iii. Permanent pressure loss is less than orifice.

iv. It has high flow velocity.
v. They are used for high pressure and steam.

III. Disadvantages:

i. Compared to orifice meter, it is expensive and also difficult to install.

ii. They are limited to moderate pipe sizes, not available above 120 cm.
iii. Cost is more compared to the orifice meter.

IV. Applications:

i. They are specially used for steam flow measurement.

24. DIFFERENT TYPES OF FLOW MEASURING DEVICES


23 SYP Aurangabad

8) VENTURIMETER:
1. Construction and Working:

i. Cylinder Entrance Section:

1. This section has the size of pipe to which it is attached.

ii. Covering Conical Section:

1. The converging takes place at an angle of 120 degree the velocity of
fluid increases as it passes through the converging section and
correspondingly the static pressure falls.

iii. Throat:

1. This is a cylinder section minimum are.

2. At this section the velocity is maximum and the pressure is minimum.

3. The throat diameter is usually between 1/2 to 1/4 of the inlet diameter.
The length of the throat equals its diameter.

iv. Diverging Section:

1. In which there is a change of stream area back to the entrance area.

25. DIFFERENT TYPES OF FLOW MEASURING DEVICES


24 SYP Aurangabad


Fig.08: Venturi-meter.




2. The recovery of kinetic energy by its conversion to pressure is nearly
complete and so the overall pressure loss is small.

3. To accomplish a maximum recovery of kinetic energy the diffuser section
is made with an included angle 5 to 7 degree.

26. DIFFERENT TYPES OF FLOW MEASURING DEVICES


25 SYP Aurangabad

2. Advantages:
i. High pressure recovery is attainable.

ii. Because of smooth surface, the meter is not much affected by wear and
abrasion.

iii. Well established characteristics.

iv. Less likelihood of becoming clogged with sediment.

v. Due to low value of losses the co-efficient of discharge is high.


3. Limitations:
i. They are expensive.

ii. Long laying length and not suitable for small pipes.

iii. Quite expensive in installation and replacement.

iv. Difficult to construct particularly so as to provide reproducibility.

27. DIFFERENT TYPES OF FLOW MEASURING DEVICES


26 SYP Aurangabad

CONCLUSION:
1. Learn the different types of flow measuring devices and its construction and
working with the neat labelled sketch.

2. Able to identify the flow measuring devices

28. DIFFERENT TYPES OF FLOW MEASURING DEVICES


27 SYP Aurangabad


Admin | [Course Title] | [Date]