Compute the flow coefficient Kv (m³/h at 1 bar Δp) and Cv (US gpm at 1 psi Δp) for a control valve, given flow rate, pressure drop and specific gravity. Per IEC 60534 / ISA 75.
Kv (m³/h) (m³/h @ 1 bar)—
Cv (USgpm) (USgpm @ 1 psi)—
Formula
Liquids, turbulent, non-cavitating :
Kv = Q · √(SG / ΔP)
Q in m³/h
ΔP in bar
SG specific gravity (water = 1)
Cv = 1.156 · Kv (US units convention)
Reference: IEC 60534-2-1, ISA 75.01
Computes the valve flow coefficient required to pass a given flow rate at a specified pressure drop, for incompressible liquids in the turbulent flow regime.
Specific gravity (SG) is the ratio of fluid density to water density. Water = 1.0, common organic solvents are around 0.7-0.9, brines / sodium hydroxide solutions up to 1.4. For gases or compressible flow, use the gas Kv formula instead (different equation).
