The document compares different flow measuring devices, including orifice meters, Venturi meters, rotameters, and Pitot tubes. It discusses how each device works, including that orifice meters use a drilled plate to measure pressure changes, Venturi meters use converging pipes to increase velocity and measure pressure differences, rotameters measure the position of a float inside a tapered tube, and Pitot tubes measure velocity by comparing static and impact pressures. The document concludes by comparing the devices based on their suitability for different fluid types, pressure losses, accuracy, and most common use in chemical industries.

2.  The
objective of our presentation
is comparisons of different flow
measuring devices

3. 
Orifice meter

Venturi meter

Rota meter

Pitot tube

4. 

The most diverse substances are transported
and distributed in piping system in every
single day they may include solvents ,
chemicals oil&gas , drinking water , fruit
juices , slurries etc
The fluid flowing through pipe often have
completely different properties consequintly
there are different principles and different
flow measuring devices

5. 

A simple instrument made by inserting drilled
orifice plate between two pipe flanges and
arranging suitable pressure connection.
An orifice plate is thin plate with a hole in
middle which helps to measure flow rate.

9. 
Some three years ago swiss mathematician
and physicsts danel bernulli discover direct
relationship between pressure and speed of
fluid flowing in a pipe. italian physicsts
batista venturi also perform experiment on
flow and in 1797 he build first flow meter
known venturi tube

11. 

A meter consist of short converging pipe
relatively longer pipe diverging with suitable
pressure differential measurement.
When fluid passes through converging side
its velocity increases maximum at throat and
and become same after passing throat

15. 

Rotameter consist of tapered tube made by
glass or plastic with a float inside that is free
to move
A rotameter is device measure flow rate of
liquid and gas in a closed tube
It belongs to class of meters called variable
flow meter in which pressure drop remain
constant and flow varies directly with cross
sectional area

17. 
When fluid enter from bottom it exert force
on float and float move up when gravitational
and force exerted by liquid become equal
equlibrium exist and float becomes stationary
then flow rate measure by graduation scale
on float

19. 

Pitot tube is pressure measure instrument
used to measure fluid flow velocity.
Pitot tube measure local velocity at given
point in stream not average velocity in pipe.

20. 
When pitot tube placed in a pipe from which
fluid is flowing as pitot tube has two tubes
one with large diameter having holes which
measure static pressure . while fluid entering
small tube on striking become rest kinetic
energy converted into pressure energy
exerted a pressure called impact pressure the
difference in total pressure minus static
pressure give pressure difference which give
velocity of fluid by bernoullis equation.

23. Comparison
Type
Viscous
liquid
Slurry
Gas
Pressure
loss
Accuracy% full
scale
Orifice
Limited
Poor
Good
High
±0.5to ±2%
Venturi
Limited
Limited
Good
Minimal
±0.5to ±3%
Average
±0.5%
Poor
±5to ±10%
Variable
area meter
Pitot tube
Limited
Poor
Limited
Poor
Good
Good

24. Inference…
• There are many types of flowing fluids having
different properties and nature so different
measuring instruments require
• So flow meters as we discuss in this presentation
their accuracy and effeciency depend on nature
of flowing fluid
• But most comman flow meter used in chemical
industries is orifice meter which mainly measure flow
of liquids and gases

25. cell no:+923007024407
institute of chemical engineering and technology Punjab university Lahore Pakistan