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, 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). The general formulas are as follows.

Valve Flow Coefficient Cv / Kv Formula

(Eq. 1)  \(\large{ C_v =   Q \; \sqrt{  \frac{SG}{\Delta P} } }\)

(Eq. 2)  \(\large{ Q =   C_v \; \sqrt{  \frac{\Delta P}{SG} }  }\)

(Eq. 3)  \(\large{ \Delta P =   SG\;  \left( \frac{Q}{C_v} \right)   }\)

(Eq. 4)  \(\large{ K_v =   Q\;  \sqrt{  \frac{SG}{\Delta P} } }\)

(Eq. 5)  \(\large{ Q =   K_v \; \sqrt{  \frac{\Delta P}{SG}  } }\)

(Eq. 6)  \(\large{ \Delta P =   SG\;  \left( \frac{Q}{K_v} \right)   }\)       


\(\large{ C_v }\) = valve flow coefficient (US units)

\(\large{ K_v }\) = valve flow coefficient (SI units)

\(\large{ Q }\) = valve flow rate

\(\large{ \Delta P }\) = valve pressure differential

\(\large{ SG }\) = fluid specific gravity


Tags: Equations for Pressure Equations for Flow Equations for Valves