A valve operator assembly is adapted for use with a valve. The assembly comprises a housing, an input member rotatably mounted with respect to the housing and comprising a rotational drive input, and a transmission mechanism connected to the input member and comprising a stem, the transmission mechanism being adapted to convert applied rotation of the rotational drive input into axial translation of the stem. The assembly further comprises at least one elastic actuator axially located between the input member and the stem to obtain a compression of the actuator during an axial translation of the stem towards the input member and a release of the actuator during an axial translation in the opposite direction.

A choke may include an inlet for receiving a flow stream. The choke may also include a valve assembly configured to receive the flow stream from the inlet and control the flow stream. The valve assembly may include a cage element, an external sleeve adapted for selectively and controllably articulating over the cage element to control the flow stream through the valve, and an impact screen surrounding both the cage element and the external sleeve and adapted to protect the cage element and the external sleeve from impacts from large objects in the flow stream. The choke may also include an outlet for delivering the flow stream from the valve assembly.

A choke may include an inlet for receiving a flow stream. The choke may also include a valve assembly configured to receive the flow stream from the inlet and control the flow stream. The valve assembly may include a cage element, an external sleeve adapted for selectively and controllably articulating over the cage element to control the flow stream through the valve, and an impact screen surrounding both the cage element and the external sleeve and adapted to protect the cage element and the external sleeve from impacts from large objects in the flow stream. The choke may also include an outlet for delivering the flow stream from the valve assembly.

A fast blind plate switching device, comprising a sealing structure, a clamping structure, a support structure and an execution mechanism. The blind plate has an open-state structure and a blind-state structure. The support structure is used for connecting pipelines at two sides and providing support for the whole device. The clamping structure and the sealing structure are located inside the support structure. The clamping structure is driven by the execution mechanism, and under the drive of the execution mechanism, the clamping structure presses on the blind plate (1) to eliminate a gap between two sides of the blind plate, so that a seal is formed by means of the sealing structure. When a gap is formed away from the blind plate (1), the open/blind state of the blind plate (1) is switched.

A fast blind plate switching device, comprising a sealing structure, a clamping structure, a support structure and an execution mechanism. The blind plate has an open-state structure and a blind-state structure. The support structure is used for connecting pipelines at two sides and providing support for the whole device. The clamping structure and the sealing structure are located inside the support structure. The clamping structure is driven by the execution mechanism, and under the drive of the execution mechanism, the clamping structure presses on the blind plate (1) to eliminate a gap between two sides of the blind plate, so that a seal is formed by means of the sealing structure. When a gap is formed away from the blind plate (1), the open/blind state of the blind plate (1) is switched.

A rail vehicle includes a graywater line which is in communication with the surroundings of the rail vehicle directly or by way of a collecting container. The graywater line is equipped with a pressure protection valve, which protects a graywater line section upstream of the pressure protection valve from pressure surges occurring in the surroundings of the rail vehicle. The pressure protection valve is constructed as a pinch valve which is controlled by a control device in order to protect the graywater line section from pressure surges.

A rail vehicle includes a graywater line which is in communication with the surroundings of the rail vehicle directly or by way of a collecting container. The graywater line is equipped with a pressure protection valve, which protects a graywater line section upstream of the pressure protection valve from pressure surges occurring in the surroundings of the rail vehicle. The pressure protection valve is constructed as a pinch valve which is controlled by a control device in order to protect the graywater line section from pressure surges.

A gate valve for use in oil field applications and including a stem seal assembly and a seat seal assembly. Each of the stem and seat seal assemblies accommodate independent primary, secondary, and tertiary seals for sealing the space between the stem and the bonnet, or the seat ring and the valve body, respectively. The provision of multiple seals in each assembly provides redundancy that allows for maintenance of the seal between the components even if one or two of the individual seals fail.

A gate valve for use in oil field applications and including a stem seal assembly and a seat seal assembly. Each of the stem and seat seal assemblies accommodate independent primary, secondary, and tertiary seals for sealing the space between the stem and the bonnet, or the seat ring and the valve body, respectively. The provision of multiple seals in each assembly provides redundancy that allows for maintenance of the seal between the components even if one or two of the individual seals fail.

A gate valve for controlling flow of a fluid therethrough is provided. The gate valve includes a valve body having an outer surface, a bore, a valve cavity, a first seat pocket, a second seat pocket, and first and second fluid ports extending from the outer surface to the first and second seat pockets, respectively. First and second seats are positioned respectively within the first and second seat pockets. The seats include circumferential fluid channels and one or more conduits in fluid communication with the fluid ports for permitting a repair fluid to be injected into the ports to the faces of the seats. A gate is slidably positioned within the valve cavity between the first seat and the second seat for controlling flow of a fluid through the valve. Sand shields are also provided at the rear of the seats to capture particulates and to bias the seats against the gate.