Preliminary. The liquid result is the basic non-choked equation. It needs engineering review before anyone selects a valve. Piping geometry factors are not included.
Formula
Cv = Q × √(G / ΔP) with Q in US gpm and ΔP in psi
Kv = Q × √(G / ΔP) with Q in m³/h and ΔP in bar
Cv = Kv / 0.865
Ff = 0.96 − 0.28 × √(Pv / Pc)
ΔP max = Fl² × (P1 − Ff × Pv)
G is specific gravity relative to water. P1, Pv and Pc are absolute. Leave the choked-flow fields blank and the page says the check was not made. If the drop is above the limit, the basic Cv is not a sizing result.
Gas is the simple inlet-density estimate only. Standard flow is converted to actual inlet volume with Z, then the liquid equation is used with specific gravity equal to inlet density divided by 1000 kg/m³. The expansion factor is not applied. Normal cubic metres are at 0 °C and 101.325 kPa. Standard cubic feet are at 60 °F and the same pressure. If ΔP/P1 is above 0.3, the result is not a sizing Cv. xT and the specific-heat ratio are optional.
Check this tool
Valve Cv version 1.0.0
This records your check of the tool output. It does not change the tool or the engineering data.
