A valve device includes a valve body; a cylindrical member provided in an accommodation recess and communicating with the first flow path; a valve seat supported by the cylindrical member; a seal member interposed between the periphery of the opening of first flow path on the bottom surface of the accommodation recess and the lower end portion of the cylindrical member; an annular plate which is flexible, air-tightly or liquid-tightly fixed to an annular support portion formed on the inner peripheral surface of the accommodation recess, air-tightly or liquid-tightly fixed to an annular support portion formed on the outer peripheral surface of the cylindrical member and has a plurality of openings communicating with the second flow path; and a diaphragm that moves between an open position at which the diaphragm does not contact the valve seat and a closed position at which the diaphragm contacts the valve seat.

A manifold body includes at least first and second valve body segments each comprising an upper perimeter wall portion defining a valve cavity and a lower base portion defining one or more flow ports, a unified leak test port, a first branch leak test passage extending from the unified leak test port to an outer peripheral portion of the valve cavity of the first valve body segment, radially outward of an outer seal surface in the valve cavity, and a second branch leak test passage extending from the unified leak test port to an outer peripheral portion of the valve cavity of the second valve body segment, radially outward of an outer seal surface in the valve cavity.

An actuator is configured to couple with a controlled member and includes first and second pistons disposed in respective internal chambers. The first piston may be moveable between first and second positions. The second piston may be moveable between third and fourth positions. The second piston may be configured not to engage the first piston when the second piston is disposed at the third position. The second piston may be configured to move the first piston to the second position as the second piston moves from the third position to the fourth position. A resilient member may be disposed to resiliently urge the second piston toward the fourth position.

The present disclosure provides a hydraulically controlled pressure relief valve without needing a hydraulic power unit. The valve maintains the accuracy of a hydraulically controlled valve by providing a self-contained closed hydraulic system built into the pressure relief valve. For safety, the valve can be kept open to call attention to the cause of the pressure relief valve activation, yet be easily reinstated into full service without replacing expendable components such as shear pins and rupture pins. The invention offers a pressure relief valve with accuracy, cost, and ease of use.

A valve device capable of precisely adjusting a flow rate includes: an operating member for operating a diaphragm and provided movably between a closed position at which diaphragm closes a flow path and an open position at which diaphragm opens the flow path; a main actuator that receives pressure from a supplied drive fluid and moves the operating member to the open position or the closed position; an adjusting actuator for adjusting the position of the operating member positioned in the open position by using a passive element which expands and contracts in response to a given input signal; a position detecting mechanism for detecting the position of the operating member with respect to a valve body; and an origin position determining unit that uses a valve closed state in which the diaphragm contacts to valve seat to determine an origin position of the position detecting mechanism.

A valve has a housing that delimits an interior, a first connection, a second connection, a passage that fluidically connects the first and second connections, first and second closing elements received in the interior and surrounding an intermediate space connected to a third connection, and an adjustment device that, in a closed position, brings the first closing element into sealing contact with a first valve seat formed in the passage and the second closing element into sealing contact with a second valve seat formed in the passage. The first closing element is sealingly received in the second closing element. For cleaning, the adjustment device forms a gap that connects the intermediate space to the interior, between the first and second closing elements and simultaneously releases the first and second closing elements from the first and second valve seats in an open position. A cleaning method is also described.

A manifold body includes a body block, with one or more end connections each extending laterally outward from a first surface of the body block, one or more lower valve cavities each recessed laterally inward from the first surface, one or more upper valve cavities each recessed laterally inward from the first surface and connected with a corresponding one of the one or more lower valve cavities by a vertically extending second passage, one or more lower end ports each extending laterally outward from a second surface of the body block and connected with a corresponding one of the one or more lower valve cavities by a laterally extending third passage, and one or more upper end ports each extending laterally outward from the second surface and connected with a corresponding one of the one or more upper valve cavities by a laterally extending fourth passage.

An actuator includes a housing defining an inlet port, a piston and a return spring disposed within the housing, and an elastically deformable element. The return spring is configured to apply a biasing force to the piston to move the piston to a spring return position. A first fluid pressure applied to the inlet port moves the piston against the biasing force of the return spring to a first actuated position in which the piston indirectly engages a stop portion of the actuator housing. A second fluid pressure, greater than the first fluid pressure, applied to the inlet port moves the piston against the elastically deformable element to compress the elastically deformable element to move the piston to a second actuated position beyond the first actuated position.

A valve arrangement for a pressurized fluid source includes a valve housing comprising an inlet, an outlet, and a main fluid channel extending along a longitudinal axis of the valve housing. The valve arrangement further includes a spool and a regulating poppet valve coaxially located in the main fluid channel. The spool and a regulating poppet valve are both configured to translate along the longitudinal axis of the valve housing independent of each other. In response to the spool moving to an open position, the poppet valve regulates the flow of a pressurized fluid flowing from the inlet to the outlet of the valve housing.

A four-position switching valve includes first and second pistons for driving a spool in a valve body, and a spool moving mechanism part that moves the spool to first and second intermediate switching positions between one-end side and the other-end-side switching positions. The spool moving mechanism part includes a compression spring that moves the spool back in the opposite direction by moving to the switching position on one end side and the other end side of the spool. The compression spring moves the spool to the first intermediate switching position when the spool moves to one-end-side switching position and the pressure on the second piston is released, and moves the spool to the second intermediate switching position when the spool moves to the other-end-side switching position and the pressure on the first piston is released.