A backflow prevention device with reduced pressure zone to be installed in water systems is provided and comprises a body provided with inlet, outlet and exhaust openings, a check assembly with a stem, an elastic element, and a plate, a mobile diaphragm or membrane adapted to interrupt the fluid connection between the outlet opening and inlet opening and between said inlet opening and exhaust opening, wherein said stem of said check assembly is stabilized with respect to said body, and said plate is slidably disposed along the stem and is cooperatively placed with the mobile diaphragm or membrane in order to interrupt the fluid connection between said inlet opening and said outlet opening.

A hydraulic control assembly includes means for holding pressure in a cylinder to inhibit boom or arm drop of a machine in the event that a hose between the cylinder and a main control valve (MCV) ruptures. The pressure holding means of the hydraulic control assembly include a hydraulic valve and a parts-in-body check assembly both configured for insertion into a valve cavity defined by a valve body. The hydraulic valve comprises a proportional piloted valve that controls pressure.

An example valve includes: a plurality of ports comprising: (i) a first port, (ii) a second port configured to be fluidly coupled to a reservoir, and (iii) a third port configured to be fluidly coupled to a source of fluid; a spool slidably accommodated in a sleeve; an annular chamber formed between the spool and the sleeve, wherein the annular chamber is fluidly coupled to the first port, and wherein a first flow area is formed between the spool and the sleeve to fluidly couple the annular chamber to the second port via the first flow area; and a solenoid coil, wherein when the solenoid coil is energized, a solenoid force the spool, thereby causing the spool to move, forming a second flow area between the spool and the sleeve to fluidly couple the third port to the annular chamber via the second flow area.

A pressure regulating and pressure relief valve, has a valve body defining an inlet port, outlet port, valve seat and pressure relief opening. A pressure regulating plug is displaced during a first portion of a motion from an open position, which provides a continuous flow path from the inlet port to the outlet port, to a closed position in which the plug is closed against the valve seat to obstruct the continuous flow path. A spring biases the plug to the open position. An actuation surface is exposed to a pressure at the outlet port that displaces the plug against the spring bias toward the closed position. Further displacement of the plug beyond the closed position during a second portion of the motion that is beyond a range of the first portion of the motion, opens a relief flow path from the outlet port through the pressure release opening.

A pressure relief valve includes a valve body having a main bore, an inlet bore which is connected to the main bore, an outlet bore which extends through a side of the valve body, and a valve bore which connects the inlet bore with the outlet bore. A valve member is positioned in the valve bore and is movable between a closed position in which a fluid in the inlet bore is prevented from flowing into the outlet bore and an open position in which the fluid in the inlet bore is permitted to flow into the outlet bore. The valve member is movable from the closed position to the open position in response to an overpressure event in the main bore. The valve body further includes a return bore which connects the inlet bore with the main bore.

A filter assembly has a housing with a housing inlet and a drain. A rotary vessel is rotatably mounted within the housing and has a rotary vessel inlet and a rotary vessel outlet. Fluid exiting the rotary vessel outlet exits the housing through the drain. A valve assembly moveable between a closed and an open configuration is provided. When closed, the valve assembly fluid-tightly seals rotary vessel inlet from housing inlet. When open, the rotary vessel inlet is in fluid communication with the housing inlet such that fluid flowing into the housing inlet passes into the rotary vessel inlet. The valve assembly is moveable from closed to open configuration when a pressure of fluid flowing into the housing inlet exceeds a threshold pressure. The filter assembly has a fluid passageway permitting air flow into the rotary vessel through the rotary vessel inlet when the valve assembly is closed.

A relief valve that includes a tube; a valve configured to slide along an inner wall of the tube in an axial direction, and a spring that urges the valve, wherein the valve has a hydraulic pressure receiving surface on a first axial side that is one side in the axial direction, and a spring abutment against which the spring abuts, on a second axial side opposite to the first axial side, and the tube has a discharge oil passage having an opening in the inner wall and extending through the inner wall in a radial direction.

An example valve includes: a plurality of ports comprising: (i) a first port, (ii) a second port configured to be fluidly coupled to a reservoir, and (iii) a third port configured to be fluidly coupled to a source of fluid; a spool slidably accommodated in a sleeve; an annular chamber formed between the spool and the sleeve, wherein the annular chamber is fluidly coupled to the first port, and wherein a first flow area is formed between the spool and the sleeve to fluidly couple the annular chamber to the second port via the first flow area; and a solenoid coil, wherein when the solenoid coil is energized, a solenoid force the spool, thereby causing the spool to move, forming a second flow area between the spool and the sleeve to fluidly couple the third port to the annular chamber via the second flow area.

The present disclosure provides a backflow prevention device, comprising: an inlet chamber comprising at least two ports, in which a first port is used for receiving a fluid; a chamber-separating component comprising a separating member and a relief valve; an outlet chamber separated from the inlet chamber by the separating member; the relief valve being operatively connected with the separating member for opening or closing a drain port of the outlet chamber; wherein the fluid is allowed to be delivered from the outlet chamber only when the relief valve is closed by means of a differential pressure applied on the separating member. Also provided is a dialysis apparatus comprising the backflow prevention device. According to the present disclosure, the backflow prevention device has simple structure, reduced dead space and small sizes and can work reliably.

A dual lock flow gate includes a valve with a flapper which may be fixed and/or locked in various positions for example to prevent fluid flow in the production string during lowering of the production string in the casing by blocking flow in the production string with the dual lock flow gate or for example to prevent rotation of the pump motor by preventing fluid flow in the production string.