A valve body comprises an inner compartment extending along a longitudinal axis from a second end portion towards a first end portion. First, second, and third fluid ports in to the valve body are perpendicular to the longitudinal axis. The second fluid port is between the third and the first fluid port. A fourth fluid port is parallel to the longitudinal axis. A spool is configured to selectively reciprocate in the inner compartment. The spool comprises a first fluid receptacle configured to block fluid flow to the third fluid port and to fluidly communicate with the second fluid port when the spool adjoins the first end portion. The first fluid receptacle is configured to fluidly communicate with the second fluid port and with the third fluid port when the spool adjoins the second end portion. A second fluid receptacle is configured to receive fluid pressure from the fourth fluid port.

A double-solenoid directional control valve comprising a valve body and a valve spool within the valve body, where the valve spool is configured to move within the valve body between a first position, a second position and a third position, where the third spool position lies between the first and second spool positions. In certain embodiments, the spool is maintained in the first and third positions by energizing at least a first or a second solenoid actuator, and where the spool is maintained in the second position by de-energizing both solenoid actuators.

A gas-over-oil actuator system for use with a valve in a natural gas pipeline. The system includes a gas-over-oil actuator and a wireless position monitor operatively coupled to the gas-over-oil actuator. The wireless position monitor includes an integral opened spool valve and is adapted to be communicatively coupled to a remote workstation via a wireless network and a wireless gateway. At least one switching relay is operatively coupled to the gas-over-oil actuator and the wireless position monitor. Upon receiving a wireless command from the remote workstation, the wireless position monitor drives a pressure signal from the opened center spool valve to the at least one switching relay to manage high pressure supply to the gas-over-oil actuator and move the valve to a desired position.

An example control system includes: a source of fluid; a cylinder actuator having: (i) cylinder, and (ii) a piston movable within the cylinder and dividing an internal space of the cylinder into a first chamber and a second chamber; a pressure control valve; a pilot-operated valve having a pilot port that is fluidly coupled to the source; and a proportional control valve configured to fluidly couple the source of fluid to the second chamber.

A flow passage switching unit includes a valve body in which plural ports are formed, a spool arranged slidably in axial directions in the interior of the valve body, a spool drive unit for driving the spool in an A direction, a biasing mechanism that is configured to bias the spool elastically in the interior of the valve body, and a piston section that exerts a force on the spool in a B direction based on the pressure of a first output port.

A proportional pressure controller includes a body having inlet, outlet, and exhaust ports. A fill valve communicates with pressurized fluid in the inlet port. A dump valve communicates with pressurized fluid from the fill valve. An inlet poppet valve opens by pressurized fluid through the fill valve. An exhaust poppet valve when closed isolates pressurized fluid from the exhaust port. An outlet flow passage communicates with pressurized fluid when the inlet poppet valve is open, and communicates with the outlet port and an exhaust/outlet common passage. An isolation valve assembly selectively isolates fluid flow to and from the inlet port or the exhaust port to achieve a zero pressure condition.

A method includes using two parallel electrohydraulic servo valves EHSVs with a single transfer valve to move an actuator during a normal operation mode. The method includes upon failure of one of the EHSVs, using the single transfer valve to disconnect a non-operational one of the EHSVs and continuing to move the actuator with a functional one of the EHSVs in a backup mode.

For connecting high pressures and flows, a safety valve includes a first main stage which, in a rest position, connects a fluid outlet to a first relief outlet and, in a switched position, connects a fluid inlet to a fluid connection for a second main stage. The second main stage, in a rest position, connects the fluid outlet to a second relief outlet and, in a switched position, connects the fluid connection to a fluid outlet. Both main stages are configured as seat valves having multipart tappets and, when the first main stage is connected, a first tappet part that is actuated counter to a spring load, in a first movement portion, initially sealingly abuts a second tappet part, as a result of which a relief passage to the first relief outlet is closed.

A method of controlling an actuator includes switching a primary solenoid valve to a first mode to fluidically connect a supply pressure source to a control chamber of a pilot valve. A fluid from the supply pressure source is directed through the primary solenoid valve to fill the control chamber of the pilot valve and put the pilot valve in a first position. The first position fluidically connects a second chamber of the actuator to a return pressure source. The actuator includes a cylinder between the first chamber and the second chamber and a rod attached to the cylinder. The fluid from the supply pressure source is directed into the first chamber of the actuator to move the cylinder and the rod in a first direction while the pilot valve is in the first position.

A gas-over-oil actuator system for use with a valve in a natural gas pipeline. The system includes a gas-over-oil actuator and a wireless position monitor operatively coupled to the gas-over-oil actuator. The wireless position monitor includes an integral opened spool valve and is adapted to be communicatively coupled to a remote workstation via a wireless network and a wireless gateway. At least one switching relay is operatively coupled to the gas-over-oil actuator and the wireless position monitor. Upon receiving a wireless command from the remote workstation, the wireless position monitor drives a pressure signal from the opened center spool valve to the at least one switching relay to manage high pressure supply to the gas-over-oil actuator and move the valve to a desired position.