National-Oilwell Varco, Inc. has released a new pneumatic AUP piston actuator for pneumatically operated safety systems.
The actuator is designed to close a reverse-acting gate valve upon loss of pneumatic pressure. The actuator can be installed on secondary master valves, pipeline system valves, wing valves, header valves, flowline valves, and casing relief blowdown valves.
During operation of the actuator, pneumatic control pressure enters the cylinder above the piston. The extended stem travels downward, indicating the valve is open. The actuator is designed to maintain the valve (reverse-acting) in the open position with pneumatic pressure on top of the piston.
Any loss of pneumatic pressure allows pressure in the valve body to move the stem and gate into the closed position. The metal-to-metal up-stop between the actuator bonnet and lower stem serves as a secondary seal when high temperatures have melted or distorted lower stem packing.
The max actuator working pressure is 375 psi. The actuators are available in various sizes for API gate valves from 113/16 to 48 in.
Image credit: National-Oilwell Varco