Abstract: A check valve is comprised of a body having inlet and outlet passages and a cylindrical chamber within the body, the axis of which forms an angle with the axis of the inlet and outlet passages. An orifice plate in the cylindrical chamber divides the chamber into a dashpot chamber and a valve chamber which is in communication with the inlet and outlet passages. A valve seat in the valve chamber separates the inlet and outlet passages. A valve closure element is mounted for reciprocation in the valve chamber between a valve open position and a valve closed position where an element is seated upon the seat. A piston is mounted for reciprocation in the dashpot chamber. A piston rod extends through an opening in the orifice plate and connects the closure element and the piston. Means are provided to apply the pressure in the outlet passage to the piston to urge the piston and closure element toward valve closed position.

Abstract: A force limiting device for an actuator rod is used on a valve actuator of the type which includes hydraulic fluid being selectively applied to and discharged from a cylinder at a first side of a piston connected to the actuator rod as high pressure gas of an accumulator mounted on the cylinder acts in opposition thereto on a second side of the piston. The piston includes an interior cylindrical bore narrowing to an opening at the first side thereof which receives the actuator rod slidably therein. The actuator rod extends from the first side of the piston through a hole in the first end of the cylinder for coupling to a valve stem outwardly of the cylinder. An enlarged piston head is secured at a first side thereof to the other end of the rod and disposed within the interior cylindrical bore for sliding, sealed contact with an interior of the bore. Atmospheric pressure communicates with the bore to act on the second side of the piston head.

Abstract: A coupling is mounted between a valve stem of a valve and a rod of a valve actuator. The rod includes an extension having a piston member at the end thereof which is received within a cylinder member mounted on the end of the valve stem. The extension and piston member thereof define with the cylinder member a chamber within the cylinder member. Force can be transmitted from the rod to the stem by full insertion of the piston member within the cylinder member. A pressurized gas is contained within the chamber to limit the force transmitted from the rod to the stem when the relative position of the rod with respect to the stem causes the piston member to be located intermediate of the cylinder member.

Abstract: A coupling is mounted between a valve steam of a valve and a rod of a valve actuator. The rod includes an extension having a piston member at the end thereof which is received within a cylinder member mounted on the end of the valve stem. The extension and piston member thereof define with the cylinder member a chamber within the cylinder member. Force can be transmitted from the rod to the stem by full insertion of the piston member within the cylinder member. Hydraulic fluid under pressure from an accumulator secured to the cylinder member is in communication with the chamber to limit the force transmitted from the rod to the stem when the relative position of the rod with respect to the stem causes the piston member to be located intermediate of the cylinder member.