Valve Flow Coefficient Cv / Kv

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Valve flow coefficient, abbreviared as \(C_v\), also called valve sizing coefficient, a dimensionless number, is the number of US gallons of water at 60°F that will flow throuhg a valve in one minute when the pressure differential across the valve is one pound per square inch (psi).

 

Valve Flow Coefficient Cv / Kv Formulas

\(\large{ C_v =   Q  \sqrt{  \frac{SG}{\Delta P} } }\) 
\(\large{ Q =   C_v  \sqrt{  \frac{\Delta P}{SG} }  }\) 
\(\large{ \Delta P =   SG  \left( \frac{Q}{C_v} \right)   }\) 
\(\large{ K_v =   Q  \sqrt{  \frac{SG}{\Delta P} } }\)
\(\large{ Q =   K_v  \sqrt{  \frac{\Delta P}{SG}  } }\)
\(\large{ \Delta P =   SG  \left( \frac{Q}{K_v} \right)   }\)

Where:

 Units English Metric
\(\large{ C_v }\) = valve flow coefficient (US units) \(\large{ dimensionless }\)
\(\large{ K_v }\) = valve flow coefficient (SI units) \(\large{ dimensionless }\)
\(\large{ Q }\) = valve flow rate \(\large{\frac{ft^3}{sec}}\) \(\large{\frac{m^3}{s}}\)
\(\large{ \Delta P }\) = valve pressure differential \(\large{\frac{lbf}{in^2}}\) \(\large{\frac{N}{m^2}}\)
\(\large{ SG }\) = specific gravity of fluid \(\large{ dimensionless }\)

 

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Tags: Equations for Pressure Equations for Coefficient Equations for Flow Equations for Valves Equations for Valve Sizing