A backflow prevention device including a tank inside of and moveable relative to a housing. A cap coupled to the housing and including inlet and outlet chambers fluidly connected through an inlet, the outlet chamber communicating with the tank. A shell is connected to the cap and includes a shell inlet chamber, which communicates with a first outlet hole of the inlet chamber, and a second outlet hole, which communicates with the tank. An inlet sealing member opens/closes the inlet to fluidly connect/disconnect the inlet chamber and the outlet chamber; and an outlet hole sealing member is moveable with the tank to open/close the second outlet hole. Closing the second outlet hole prevents water from flowing through the second outlet hole and switches the inlet from open to closed. Opening the second outlet hole allows water to flow through the second outlet hole and switches the inlet to open.

An electronically-controlled pressure regulator includes an inlet through which a gas or liquid is introduced at an inlet pressure, an outlet through which the gas or liquid exits at an outlet pressure, and a valve disposed between the inlet and the outlet, the valve defining a passage including a throat and having a pintle with an enlarged shoulder, the valve movable between a closed configuration in which the enlarged shoulder seals the throat to prevent the gas or liquid from passing from the inlet to the outlet through the valve, and an open configuration in which the gas or liquid can pass from the inlet to the outlet through the valve. In a valve flow path, the enlarged shoulder is disposed between the inlet and the throat. All of the gas or liquid that enters through the inlet can exit through the outlet.

A system for adjusting pressure of a gas includes: a first shutter unit for causing a pressure drop in the gas, from a supply pressure to a delivery pressure; a pilot unit for providing a pilot pressure depending on the difference between the delivery pressure and a predefined setting pressure; a first drive unit operated by the pilot pressure to reduce the opening of the first shutter unit when the delivery pressure exceeds the setting pressure, and vice versa; a second shutter unit in series with the first shutter unit can assume a closed configuration; a second drive unit operated by the pilot pressure to reduce the opening of the second shutter unit when the delivery pressure exceeds the setting pressure, and vice versa. When the first shutter unit is open the opening of the second shutter unit causes a pressure drop smaller than the pressure drop by the first shutter unit.

A diaphragm-type control valve having a diaphragm and a valve body is provided preferably for use in the separation of and fluid control between a fluid source and a pressurized gas volume. The diaphragm element and a port in the body together form an intermediate chamber that eliminates the need for a check-valve downstream of the valve. In one preferred embodiment, an inner surface of the valve body defines a chamber having an inlet and an outlet in communication with the chamber, and an elongated seat member defining a groove in communication with the port. A diaphragm member having upper and lower surfaces is disposed within the chamber. The lower surface preferably includes a pair of spaced apart elongated members defining a channel therebetween. The diaphragm member engages the seat member placing the channel in communication with the groove to define an air seat in communication with the port.

A modular hydraulic control valve assembly for use in a pilot-operated hydraulic control system comprises, in one embodiment, a control valve including a valve body defining a main flow passage from an inlet on a high pressure side of the control valve to an outlet on a low pressure side of the control valve, a valve member arranged in the flow passage and separating the high pressure side from the low pressure side, a control chamber comprising means for hydraulic actuation of the valve member by applying a control pressure to the control chamber so as to position the valve member between an open position and a closed position thereby adjusting a main flow through the main flow passage in response to the control pressure, a feed port for feeding fluid to the control chamber to increase the control pressure therein, a bleed port for bleeding fluid from the control chamber to decrease the control pressure therein, and a valve bonnet closing the control chamber. The assembly further comprises a feed check valve determining a feed flow direction, a bleed check valve determining a bleed flow direction, a distribution block including a common plenum, a control input in fluid communication with the common plenum, and a control output in fluid communication with the common plenum, wherein the distribution block further comprises a feed channel connecting the common plenum with the feed port via an adjustable feed constriction, and a bleed channel connecting the common plenum with the bleed port via an adjustable bleed constriction.

A valve assembly for an air flow system, where the air flow system has a turbocharger unit and a venturi valve member for receiving a portion of the pressurized air from the turbocharger unit, and generating back pressure. The valve assembly includes a bypass switching valve and a bypass check valve. During a first mode of operation, the valve assembly is exposed to vacuum pressure, and the bypass check valve is exposed to the vacuum pressure such that the bypass check valve is placed in a closed position. During a second mode of operation the turbocharger unit is activated, pressurized air flows through the bypass switching valve, and places the bypass check valve in an open position, and the back pressure generated by the venturi valve member and the pressurized air from the turbocharger unit creates a pressure differential in the bypass check valve.

A diaphragm-type control valve having a diaphragm and a valve body is provided preferably for use in the separation of and fluid control between a fluid source and a pressurized gas volume. The diaphragm element and a port in the body together form an intermediate chamber that eliminates the need for a check-valve downstream of the valve. In one preferred embodiment, an inner surface of the valve body defines a chamber having an inlet and an outlet in communication with the chamber, and an elongated seat member defining a groove in communication with the port. A diaphragm member having upper and lower surfaces is disposed within the chamber. The lower surface preferably includes a pair of spaced apart elongated members defining a channel therebetween. The diaphragm member engages the seat member placing the channel in communication with the groove to define an air seat in communication with the port.

A diaphragm-type control valve having a diaphragm and a valve body is provided preferably for use in the separation of and fluid control between a fluid source and a pressurized gas volume. The diaphragm element and a port in the body together form an intermediate chamber that eliminates the need for a check-valve downstream of the valve. In one preferred embodiment, an inner surface of the valve body defines a chamber having an inlet and an outlet in communication with the chamber, and an elongated seat member defining a groove in communication with the port. A diaphragm member having upper and lower surfaces is disposed within the chamber. The lower surface preferably includes a pair of spaced apart elongated members defining a channel therebetween. The diaphragm member engages the seat member placing the channel in communication with the groove to define an air seat in communication with the port.

A system can include one or more valve arrangements with a working chamber to receive a working fluid at a first pressure, and a control chamber to receive fluid at a second pressure. A dynamic seal can be disposed on a land of a valve element. The valve arrangement may include a sleeve against which the dynamic seal is slidably engaged. The valve element may include a check stem. A pressure compensating system may be in communication with bores formed in with the valve element. A pressure system to monitor dynamic seal wear may be in communication with the control chamber of the valve arrangement.

A main valve seat surface for engaging the piston, an outer sidewall, and an inner sidewall defining a flow passage with a first opening and an second opening, the flow passage having a reduced diameter portion.