How to Determine Proper Air Valve SizeExample: Cylinder size 4” Dia. x 10” stroke. Time to extend: 2 seconds. Inlet pressure 90 psiG. Allowable pressure drop 5 psiD. Determine Cv.
F = 12.57 Sq. In. (Table 1)
C = 7.1 (Table 2) B = 21.6
Cv = 12.57 x 10 x 7.1 = 0.7
21.6 x 2 x 28.8
Select a valve that has a Cv factor of .7 or higher. In most cases, a 1/4” valve would be sufficient.
It is considered good engineering practice to limit the pressure drop Dp to approximately 10% of primary pressure P1. The smaller the allowable pressure drop, the larger the required valve will become.
After the minimum required Cv has been calculated, the proper size valve can be selected from the catalog.