Abstract: A valve actuator for surface and sub-sea applications is disclosed. The valve actuator stem is hydraulically actuated by a piston attached to it. A fluid filled reservoir with a pump which preferably operates on 24 volts D.C. is included in the actuator housing. The pump draws fluid from the reservoir and pumps it against the piston. A solenoid valve allows bypass from beneath the piston back to the reservoir for fail safe operation in the event of power loss. Positional sensors on the actuator stems trigger the operation of the pump. As long as 24 volts D.C. power is available the pump may selectively run if the actuator stem position changes for any reason.