Abstract: A valve actuator comprising a lower housing comprising a mounting spool that is operable to couple to a valve body. A rotating sleeve is disposed within the lower housing and coupled to a stem connector. A fixed sleeve in disposed within the lower housing and includes a first slot disposed therethrough. A second slot is disposed in the rotating sleeve, wherein at least one of the slots is a helical slot. An axle engages both the first slot and the second slot. A shaft is coupled to the axle and extends through a connector flange that is coupled to an upper end of the lower housing. A piston is coupled to the shaft and movably disposed within an upper housing that is coupled to the connector flange. Axial movement of the piston within the upper housing will result in rotational movement of the rotating sleeve.

Abstract: A hydraulic control system for a valve actuator comprising a first control valve that regulates fluid communication from a fluid pressure source to a first fluid supply tank that is fluidly connected to the valve actuator. A second control valve regulates fluid communication from the fluid pressure source to a second fluid supply tank that is fluidly connected to the valve actuator. A flow control member regulates fluid communication between the first and second fluid supply tanks and an exhaust valve that regulates fluid communication between the first and second fluid supply tanks and an outlet.

Abstract: A valve, actuator and control system that allows minimizing the size of the actuator and operation of the control system in a manual mode that automatically prevents accidental operation by pipeline pressure is disclosed. The actuator uses gas pressure from the pipeline to power the actuator. In the event gas pressure is unavailable, a pair of manual hand pumps are incorporated to allow operation of the actuator and valve.