Actuator for a valve

Abstract

The following invention relates to an actuator for controlling a valve () in a subsea installation, the valve having a spring () to return the valve to a failsafe condition upon loss of pressure. The actuator comprises an actuator module () that is exchangeably connected to the valve and comprising a cylinder with a movable piston (), the piston being mechanically connected to said valve element, a fluid pump () operatively connected to said hydraulic cylinder, said pump adapted to supply fluid through a first hydraulic line () operatively connected between said hydraulic cylinder and said pump, said hydraulic line supplying a sufficient pressure to move the piston to said second position to cause the valve element to move to its second position, and a second hydraulic line () providing a fluid passage between the first hydraulic line and a reservoir () whereby a bypass control unit () is located in said second hydraulic line and comprising a movable element operating to open or close said fluid passage through the second hydraulic line providing a failsafe function to the valve. According to the invention a third hydraulic line () is connected to the second hydraulic line and acting on the movable element, forcing the control unit towards opening said passage.