A drain valve for a pressurised fluid chamber comprises a collection chamber for collecting pressurised fluid from the pressurised fluid chamber; a vent chamber for venting the pressurised fluid from the collection chamber; a master valve between the collection chamber and the vent chamber; and a slave valve between the pressurised fluid chamber and the collection chamber. The master valve is configured to open the slave valve when the master valve is closed, and to close the slave valve when the master valve is open. The master valve is configured to open the slave valve to allow pressurised fluid from the pressurised fluid chamber to enter the collection chamber, and configured to close the slave valve to allow pressurised fluid from the collection chamber to enter the vent chamber. The master valve and the slave valve cannot be shut at the same time.

A drive system for raising or lowering a sliding piece of a current collector for rail vehicles. The sliding piece is disposed on a positioning device of the current collector, and the sliding piece is configured to be brought into contact with an overhead line using contact pressure. The drive system includes a bellows drive which is actuated by compressed air to actuate the positioning device, and a pneumatic control unit having a control valve for supplying or withdrawing compressed air to/from the bellows drive. The drive system includes a detection line and a lowering valve for venting the bellows drive when pressure drops in the detection line, the lowering valve being a 3/2-way valve disposed in a pneumatic supply line between the control valve and the bellows drive.

A drive system for raising or lowering a sliding piece of a current collector for rail vehicles. The sliding piece is disposed on a positioning device of the current collector, and the sliding piece is configured to be brought into contact with an overhead line using contact pressure. The drive system includes a bellows drive which is actuated by compressed air to actuate the positioning device, and a pneumatic control unit having a control valve for supplying or withdrawing compressed air to/from the bellows drive. The drive system includes a detection line and a lowering valve for venting the bellows drive when pressure drops in the detection line, the lowering valve being a 3/2-way valve disposed in a pneumatic supply line between the control valve and the bellows drive.

A mechanical shutdown valve for preventing an over pressure condition is described. A valve body has an inlet, an outlet, and a channel extending from the inlet to the outlet. A valve seat and a diaphragm are positioned in the valve body. The diaphragm controls a fluid flow through the valve body. A mesh is coupled to the diaphragm such that the mesh and the diaphragm separate an upstream portion of the channel from a downstream portion of the channel. The mesh extends from the diaphragm to an inner surface of the valve body and limits fluid flow between the diaphragm and the valve body. A spring biases the diaphragm towards the open position. A characteristic of the spring determines a differential pressure threshold between the upstream portion of the channel and a downstream portion of the channel at which the diaphragm engages the valve seat.

Provided is a diaphragm type actuator that drives an operation rod in an axial direction of the operation rod, including: a diaphragm which is connected to the operation rod; a low pressure chamber which is adjacent to one end side of the diaphragm in the axial direction; a high pressure chamber which is adjacent to the other end side of the diaphragm in the axial direction; a return spring which is provided in the low pressure chamber and urges the diaphragm toward the high pressure chamber; and a retainer which is provided on a surface near the high pressure chamber in the diaphragm. An elastic member is disposed inside the high pressure chamber and the elastic member is disposed between a retainer and a wall surface facing the retainer in the axial direction.

The invention relates to an actuator (10) for a process plant, comprising an actuating valve (14) and an actuating drive (12) which has an actuating drive housing (20) and a drive rod (18) mounted in the actuating drive housing (20), wherein the actuating drive housing (20) is connected to a valve housing (22) of the actuating valve (14) via a connecting housing. The invention is characterized in that a second rod coupling (46) and an adjusting rod (42) are provided, the adjusting rod (42) being provided in the region between the drive rod (18) and the valve rod (38), one rod coupling (44, 46) coupling the adjusting rod (42) to the drive rod (18), and one rod coupling (44, 46) coupling the adjusting rod (42) to the valve rod (18).

The invention relates to an actuator (10) for a process plant, comprising an actuating valve (14) and an actuating drive (12) which has an actuating drive housing (20) and a drive rod (18) mounted in the actuating drive housing (20), wherein the actuating drive housing (20) is connected to a valve housing (22) of the actuating valve (14) via a connecting housing. The invention is characterized in that a second rod coupling (46) and an adjusting rod (42) are provided, the adjusting rod (42) being provided in the region between the drive rod (18) and the valve rod (38), one rod coupling (44, 46) coupling the adjusting rod (42) to the drive rod (18), and one rod coupling (44, 46) coupling the adjusting rod (42) to the valve rod (18).

A pressure regulator is configured for better accuracy and response times at higher inlet pressures. These configurations may integrate two-path control with a pressure-balanced plug. The two-path control may leverage a pair of pilot valves, one with a fixed differential pressure and the other with a variable differential pressure. In one implementation, the device is plumbed so that downstream pressure is sensed at both the actuator and the variable differential pressure pilot valve.

A pressure regulator is configured for better accuracy and response times at higher inlet pressures. These configurations may integrate two-path control with a pressure-balanced plug. The two-path control may leverage a pair of pilot valves, one with a fixed differential pressure and the other with a variable differential pressure. In one implementation, the device is plumbed so that downstream pressure is sensed at both the actuator and the variable differential pressure pilot valve.

Example embodiments disclose a valve seat that encloses a fluid passage for passage of a fluid from a fluid chamber, and a holding element that exerts a holding force on a valve body, the holding force acting in a direction towards a valve seat. In the event that the fluid acts on an effective surface of the valve body with a force or a pressure above a limit value, the valve body moves away from the valve seat. In the event that the fluid acts on an effective surface of the holding element with a force or a pressure above a limit value, the holding force acting on the valve body decreases. In doing so, the fluid acts on the holding element more strongly and/or earlier than on the valve body.