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venturi_meter ppt(2)

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venturi_meter ppt(2)

  1. 1. VENTURI METER Presented By: •Ateeb Ahmed •Syed Ali Ikram •M. Iqbal Awais •M.Waleed Mushtaq 1
  2. 2. Flow measuring devices:  The measurement of fluid flow is important in applications ranging from measurements of blood- flow rates in human artery to the measurement of liquid oxygen in a rocket.  Some sort of restriction is placed in the pipe or duct carrying the fluid. This flow restriction causes a pressure drop that varies with the flow rate. 2
  3. 3. Venturi Meter:  A venturi meter is a variable head meter, which is used for measuring the flow rate of a fluid through a pipe.  In this meter, the fluid is gradually accelerated to a throat and then gradually retarded in diverging section where the flow channel expands to the pipe size.  Venturi meters have only a small head loss, no moving parts and do not clog easily. 3
  4. 4. Working principle:  By reducing the cross-sectional area of the flow passage, a pressure difference is created and the measurement of the pressure difference enables the estimation of the flow rate through the pipe. 4
  5. 5. Oggy and the cockroaches 5
  6. 6. Construction: A venturi meter consists of following three parts: 1. A short converging conical part 2. Throat and 3. Diverging conical part 6
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  8. 8. 8 = density of fluid A1 = area of inlet pipe A2=area of throat section 
  9. 9. 9
  10. 10. Coefficient of discharge:  Ratio of Actual mass or volumetric flow rate to theoretical mass or volumetric rate .  It encompasses all the energy losses taking place during flow through venturi meter.  Its value depends upon the reynolds number and ranges from 0.95 to 0.98 10
  11. 11. Working equation for venturi meter: G = Cd ρC ́ Where Cd= coefficient of discharge ρ = density of the fluid and C ́ is constant for a meter and is equal to 2 2 2 1 21 AA AA  By applying Bernoulli’s theorem at the inlet and throat sections, the relation for flow rate can be dervied as: 02gh 11
  12. 12. Applications:  It is used where we are working with small pressure head.  Can be used for measuring flow rates of water, gases, suspended solids, slurries and dirty liquids.  Can be used to measure high flow rates in pipes having diameters in a few meters.  It doesn’t clogs easily. 12
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  14. 14. Limitations:  They are large in size and hence where space is limited, they cannot be used.  Expensive initial cost, installation and maintenance.  Cannot be used in pipes below 7.5cm diameter.  Cannot be altered for measuring flow rate upto a wide range. 14
  15. 15. References:  Unit Operations of Chemical Engineering -7e by Mccabe  industrial instrumentation and control by sk singh  Coulson & Richardson's Chemical Engineering Fluid flow, heat transfer and mass transfer. Volume 1  And our very own www.google.com 15
  16. 16. Any Queries ? 16