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Diaphragm and Piston Pneumatic Actuators

Piston Pneumatic Actuator

Introduction and Operation


The TVC Piston Type Pneumatic Actuator is used to open and close a gate valve. The gate valve can be reverse acting or direct acting.  The actuator is a fail safe design. A coil spring is incorporated to assist in elevating the gate when there is no line pressure.  In a reverse acting gate valve mode, the fail safe action of the bonnet stem insures closing on loss of control supply pressure.  In a direct acting gate valve mode, with loss of control supply pressure, the fail safe actuator will open the gate valve.

The design of the actuator is rugged, easy to adapt to a bonnet and easy to maintain.  This Piston Actuator can be used on or offshore.  Normal operation would be as a secondary master or wing valve.

The maximum control pressure of the Actuator is 170 PSI (12 bar).  The test pressure is 255 PSI (18 bar).  This Actuator is designed to adapt to any “like design” gate valve in the industry.



The TVC Piston Type Pneumatic Actuator is operated by an air or gas pressure supply to the top port of the actuator head.  This gas pressure will act on the area of the piston forcing the bonnet stem down to either open or close the gate valve depending on the gate design.

In a reverse acting gate valve, having a pressure differential across the gate, the initial opening might exhibit a quick response as the pressure differential is reduced.  This does not cause damage or hinder valve function.

When control supply pressure is reduced the closing motion will be smooth without any hesitation. This action can best be described as a fail close for reverse acting gates and fail open for direct acting gates.  As a rule of motion, the larger the exhaust port in the actuator, the quicker the actuator will close.