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PIPE-FLO Professional
Formula 5 - Reduced Seat Valve, Gradual Change in Diameter
Formula 5 is used to calculate the K value for reduced seated valves with a
gradual change in diameter. Examples of valves which use Formula 5 are ball
and gate valves. Formula 5 is a combination of Formulas 1 and 3 (discussed
above) and the K value of the reduced seat valve type. For each supported
valve or fitting, a full seat L/D coefficient is stored in the valve table. PIPEFLO determines the angle of approach from the reduced seat diameter and
the approach length specified by the user in the Valve & Fitting dialog box. If
a reduced seat and approach length are not specified, the program assumes
that the valve is full seated.
K2 = KReducer + K1/β4 + KEnlarger
Formula 5
Formula 7 - Reduced Seat Valve, Abrupt Change in Diameter
Formula 7 is used to calculate the K value for reduced seated valves with an
abrupt change in diameter. Examples of valves using Formula 7 are globe,
angle, lift check, and stop check valves. Formula 7 is a combination of Formulas
1 and 3 (with the angle of approach set to 180°) and the K value of the reduced
seat valve type. A full seat L/D coefficient is stored in the table for each supported
valve or fitting. The user must specify the reduced seat diameter in the Valve
and Fitting dialog box. If a reduced seat is not specified, the program assumes
that the valve is full seated.
K2 = KReducer + K1/β4 + KEnlarger
Formula 7
Formula 8 - Elbows and Bends
Formula 8 is used to calculate the K value for elbows and bends. A coefficient
is stored in the valve and fitting table for each r/d ratio. In the Valve & Fitting
dialog box, the user must specify the angle of the elbow.
Kb = (n-1)(0.25πfT(r/d) + 0.5K) + K
Formula 8
n = number of 90° bends
K = resistance coefficient for one 90° bend
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Piping System Analysis
PFM-V0808