Inputs
1 only for no attached reducer effects. Otherwise enter the installed factor.
Use vendor data at the intended travel. With attached fittings, enter xTP paired with Fp.
Results
Choose your inputs and calculate.
Calculation basis
x = (P1 − P2)/P1; Fγ = k/1.40 xused = min(x, Fγ xT) [use xTP for installed fittings] Y = 1 − xused/(3 Fγ xT) Qscfh = 1360 Fp Cv P1,psia Y √[xused/(Gg T1,°R Z)] Kv = Cv / 1.156099 Choked when x ≥ Fγ xT; Y = 2/3 at the limit.
How to use this calculator
Enter absolute pressures and the gas properties at the inlet. Choose required Cv or capacity at a specified Cv. Use manufacturer xT for the valve opening you intend to operate at; xT changes with valve type and travel. The result is a required coefficient, not a valve size or guaranteed operating point.
Single-phase gas or vapor in the turbulent sizing regime. Absolute inlet and outlet pressures are required. Reference volumes assume Z = 1 at the stated reference conditions. Fp and xT/xTP are supplied values, not calculated from reducer geometry. Noise, outlet velocity, trim selection, and laminar corrections are not evaluated.
References
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