Cv Flow Calculator: Valve Flow Coefficient for Liquids and Gases

Your details

Choose the unknown you want to calculate; the other two must be entered.
Ratio of fluid density to water (liquids) or air (gases) at standard conditions. Only used when "Other" is selected above.
Volumetric flow rate through the valve.
GPM
Absolute upstream pressure at the valve inlet.
psia
Absolute downstream pressure at the valve outlet.
psia
The valve flow coefficient. Required when solving for flow rate or pressure drop.
Cv (flow coefficient)Incompressible
4.472

GPM of water at 60 F flowing through the valve per 1 psi pressure drop

Flow rate10
Pressure drop5
Flow regimeIncompressible (liquid)
Kv (metric equivalent)3.869
Cv (flow coefficient)4.472
Kv (metric equivalent)3.869

Cv = 4.472 - valve sizing complete.

  • A valve with Cv = 4.47 will pass the specified flow at the given pressure conditions.
  • The metric equivalent is Kv = 3.87 m³/h, useful when selecting European-rated valves.
  • The pressure drop across the valve is 5.00 psi. High pressure drops cause noise, erosion, and cavitation in liquids - consider a multi-stage valve if it exceeds 30% of P1.

Next stepUse the calculated Cv to select a valve from the manufacturer data sheet: choose a valve whose rated Cv is at least 10-20% above your calculated value to allow for wear and flow margin.

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