Relation between flowrate and butterfly valve opening

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SUMMARY

The relationship between valve opening and flowrate for butterfly and ball valves is not directly proportional. As flowrate increases, it initially rises quickly but then levels off, resembling a sideways parabola. To accurately compute flowrate, one must apply Bernoulli's equation, incorporating the percentage opening of the valve into the friction loss term. Additionally, obtaining the flow coefficient (Kf) values for both valve types is essential for precise calculations.

PREREQUISITES
  • Understanding of Bernoulli's equation
  • Knowledge of flow coefficients (Kf) for valves
  • Familiarity with fluid dynamics concepts
  • Experience with valve types, specifically butterfly and ball valves
NEXT STEPS
  • Research how to calculate flowrate using Bernoulli's equation
  • Find resources for determining Kf values for butterfly and ball valves
  • Study the impact of valve opening on flow characteristics in fluid systems
  • Explore advanced fluid dynamics simulations for valve performance analysis
USEFUL FOR

Engineers, fluid dynamics specialists, and anyone involved in the design and analysis of piping systems utilizing butterfly and ball valves.

balotpinoy
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is it right to say that valve opening for both ball & butterfly valve is directly proportional to flowrate passing through it?

say 100 m^3/hr at 100% opening
50 m^3/hr at 50% opening??

thanks in advance..
 
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Definitely not. Flow starts fast, then levels-out. Think a sideways parabola, with valve position horizontal and flow vertical.
 
so i need to compute the flowrate using bernoulli taking into account % opening of the valve in the friction loss term?

if so, where can i find values of Kf for both ball and butterfly valves..

tnx a lot..
 

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