Valve Flow Coefficient Cv / Kv

Valve flow coefficient, abbreviared as \(C_v\), also called valve sizing coefficient, a dimensionless number, uses imperial units.  The number of \(\frac{gal}{min}\) of water at 60°F that will flow through a valve in one minute when the pressure differential across the valve is 1 \(\frac{lbf}{in^2}\) (psi).

Valve flow factor, abbreviared as \(K_v\), a dimensionless number, uses imperial units.  The number of \(\frac{L}{min}\) of water between 5°C - 30°C that will flow through a valve in \(\frac{m^3}{hr}\) with a pressure drop of 1 bar.

 

Valve Flow Coefficient CV / flow Factor KV Formulas
\(\large{ C_v =   Q  \sqrt{  \frac{SG}{\Delta P} } }\) \(\large{ K_v =   Q  \sqrt{  \frac{SG}{\Delta P} } }\)
Symbol	English	Metric
\(\large{ C_v }\) = valve flow coefficient	\(\large{ dimensionless }\)
\(\large{ K_v }\) = valve flow factor	\(\large{ dimensionless }\)
\(\large{ Q }\) = 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	\(\large{ dimensionless }\)