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Fluid Control Equipment
Electro-Pneumatic Control Valves
CT Series
Direct and Reverse Actuation
This term indicates the relationship between the air supplied to the actuator of a pneumatic control valve and the open/close direction of the main valve.
Direct action
Also called 'air to close' or 'fail open', direct acting actuators operates as follows: when air is supplied to the actuator, the increase in pneumatic pressure is applied to close the valve. When air supply is stopped, the valve opens by spring force.
Reverse action
Also called 'air to open' or 'fail close', reverse acting actuators operate in the opposite direction: when air is supplied to the actuator, the increase in pneumatic pressure lifts the valve stem and the valve opens. When air supply is stopped, the valve closes by spring force.