Sviktsikker sikringsventil

摘要

A subsurface well safety valve having a flow tube telescopically movable in a housing for controlling the movement of a valve closure member. A piston and cylinder assembly actuates the flow tube and is in communication with hydraulic control fluid from the well surface on one side and a gas biasing chamber on the second side and includes a spring acting on the flow tube to close the valve. An equalizing system equalizes fluid pressure on opposite sides of the piston and cylinder assembly in the event of a failure in the seal between the piston and cylinder thereby allowing the spring to close the valve. The equalizing system uses fewer components than previous designs and utilizes a new reference chamber design that allows the reference chamber and the piston to be positioned within the same axial length reducing the overall length of the safety valve over previous designs.