How to calculate the thrust of gate valve cylinder

Gate valve thrust calculation cylinder. The calculation formula of cylinder thrust is: F=P*A-fF. The calculation formula of cylinder thrust is: F=P*A-fF: cylinder output (kgf), a: cross-sectional area (cm2), p: pressure used (kgf/cm2), f: friction resistance without rod cavity (kgf) cross-sectional area * working gas pressure = piston thrust cross-sectional area with rod cavity * working gas pressure = piston tension.