Difference between Direct and Reverse Acting valves?

Control Valves
1

The following clarified the different features between direct and reverse acting valve.

Direct acting valve

Air to close – Spring to open — Failed Open (FO)

(increasing air pressure pushes down diaphragm and extends actuator stem)

Direct%20acting%20valve

Reverse acting valve

Air to open – Spring to close — Failed Close (FC)

(increasing air pressure pushes up diaphragm and retracts actuator stem)

Reverse%20acting%20valve

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