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PIPE-FLO Professional
Fp Piping Geometry Factor
The Cv values for valves are obtained experimentally by installing the valve in a
straight run of pipe without any inlet or outlet reducers. Since many applications
of valves do require reducers, the Fp factor takes into account the effects of the
inlet and outlet reducers.
The Fp factor is defined as the ratio of the valve Cv installed with reducers to
the rated Cv of the valve installed without reducers. The following equation can
be used to determine Fp:
FP = (((KSUM Cv²)/(N2 Dv4))+1)-½
equation 2
N2 = conversion coefficient
Dv = nominal valve diameter
KSUM = K1 + K2 + KB1 - KB2
equation 3
K1 = inlet reducer resistance coefficient
K2 = outlet reducer resistance coefficient
KB1 = inlet Bernoulli coefficient
KB2 = outlet Bernoulli coefficient
PIPE-FLO calculates the values of the coefficients with the following equations
as found in the standard:
K1 = 0.5 (1 - (Dv²/D1²))²
equation 4A
K2 = 1.0 (1 - (Dv²/D2²))²
equation 4B
KB1= 1 - (Dv/D1)4
equation 4C
Control Valve Selection
PFM-V0808
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