A seal with a wedging element for adjustably compressing the seal. The seal abuts a surface, such as a gate of a gate valve, to seal against the surface with a sealing force that prevents fluid flow therebetween. The sealing force of the seal may be increasing or decreasing compression by adjusting the wedging mechanism. For example, as the seal wears away due to friction between the seal and a sliding gate, the compression may be increased in the wedging mechanism to increase the sealing force to a low threshold.

A pair of air cylinders that cause a valve plate to perform an opening/closing operation each include a head-side air cushion mechanism and a rod-side air cushion mechanism. Each head-side air cushion mechanism includes a head-side communication path and a head-side restricting flow path that connect a head-side pressure chamber and a head-side main flow path in parallel, and a blocking mechanism that blocks the head-side communication path when a piston approaches a retreat stroke end, and each rod-side air cushion mechanism includes a rod-side communication path and a rod-side restricting flow path that connect a rod-side pressure chamber and a rod-side main flow path in parallel, and a blocking mechanism that blocks the rod-side communication path when the piston approaches an advance stroke end.

An actuating apparatus for operating a valve assembly includes an actuator body that selectively couples to the valve assembly and an actuator stem that has an end that extends into the actuator body. The valve assembly has having a valve body, a valve member in the valve body, a valve stem attached to the valve member, and a profile on an end of the valve stem distal from the valve member. The actuating apparatus also includes an adapter assembly in the actuator body having a threaded end that engages the actuator stem, and a profiled end distal from the threaded end that engages the profile on the valve stem and couples to the valve stem, so that selectively applying axial forces to the adapter assembly moves the valve stem and the valve member.

An actuating apparatus for operating a valve assembly includes an actuator body that selectively couples to the valve assembly and an actuator stem that has an end that extends into the actuator body. The valve assembly has having a valve body, a valve member in the valve body, a valve stem attached to the valve member, and a profile on an end of the valve stem distal from the valve member. The actuating apparatus also includes an adapter assembly in the actuator body having a threaded end that engages the actuator stem, and a profiled end distal from the threaded end that engages the profile on the valve stem and couples to the valve stem, so that selectively applying axial forces to the adapter assembly moves the valve stem and the valve member.

A valve position indicator for a valve includes an outer housing, actuation rod, indicator flag, and follower. The actuation rod is positioned within the outer housing, which is couplable to a tail stem protector of the valve. The actuation rod may have a helical slot formed therein. The actuation rod may be rotatably coupled to the outer housing. The indicator flag may be coupled to the actuator rod and may extend radially therefrom. The follower may be couplable to a tail stem of the valve. The follower may extend in a direction perpendicular to the extent of the tail stem. The follower may extend through a slot in the tail stem protector and into the helical slot of the actuation rod when the valve position indicator is coupled to the tail stem protector.

A valve position indicator for a valve includes an outer housing, actuation rod, indicator flag, and follower. The actuation rod is positioned within the outer housing, which is couplable to a tail stem protector of the valve. The actuation rod may have a helical slot formed therein. The actuation rod may be rotatably coupled to the outer housing. The indicator flag may be coupled to the actuator rod and may extend radially therefrom. The follower may be couplable to a tail stem of the valve. The follower may extend in a direction perpendicular to the extent of the tail stem. The follower may extend through a slot in the tail stem protector and into the helical slot of the actuation rod when the valve position indicator is coupled to the tail stem protector.

In a valve having a body with a sealed working fluid chamber, a bore and a valved fluid chamber, the valved fluid chamber having an inlet and outlet and a seat between the inlet and the outlet, a piston for extending through the bore from the working fluid chamber to the valved fluid chamber, a spring for biasing the piston away from the seat and a working fluid for receipt in the working fluid chamber. Applicant provides an improvement comprising a seal stack assembly for entrainment, under compression, upon the piston and in the piston chamber between a working fluid chamber end wall and a first end of the piston, wherein the first end of the piston is located in the working fluid chamber and a second end in the valved fluid chamber.

A dual gate valve includes two valve plates that open and close two openings of a valve box, a support bar that supports the two valve plates, a valve rod connected to the support bar, and an operation unit that performs an open and close operation of the two valve plates via the valve rod. The support bar and the valve plate linearly and elongatedly extend in a lateral direction perpendicular to a central axis of the valve rod. The valve rod is connected to a central portion in the long direction of the support bar, and one and the other of the two valve plates are tiltably attached to one end and the other end in the long direction of the support bar via elastic members, respectively.

The invention relates to a shut-off device for valve systems of industrial plants, in particular of chemical and petrochemical plants, with a disc (12) to shut off an opening for a fluid flow and with a seal seat (13a). The invention is characterised in that the disc (12) is arranged between the seal seat and a pressing means (26) to subject the disc (12) to a pressing force and can be pressed by the pressing means (26) against the seal seat (13a), wherein the pressing means (26) has in a housing (10) a plurality of pistons (48) and a transmission element for transmitting the pressing force to the disc (12), the transmission element being arranged between the pistons (48) and the disc (12) and extending along the disc circumference, and wherein the pistons (48) are fluidically connected by a feed line (49) for hydraulic fluid.

Provided are methods and systems for controlling a pressure relief valve. An electronic control unit monitors pressure being supplied from a source. If the control unit determines that the monitored pressure is above a threshold pressure, the control unit controls an actuator to move the pressure relief valve to an open position, thereby releasing the pressure from within the system. If the control unit determines that the monitored pressure is at or below the threshold value, the control unit controls the actuator to move the pressure relief valve to a closed position.