Abstract: An in line pressure sensitive back flow prevention valve assembly adaptable for high volume flow applications comprising an elongated housing having a fluid inlet and outlet at opposite ends thereof, an axial control rod reciprocally mounted therein, a valve motor piston carried by one end of the rod in sliding engagement with the housing inwardly spaced from the fluid inlet and an elongated double poppet valve slidably mounted within the housing on the control rod and defining with a second slidably mounted piston, an upstream check valve and, with a slidably mounted sleeve, a downstream check valve. Biasing spring urge the motor piston toward the fluid inlet and the check valves to the closed position. The valve elements are sized to utilize the fluid forces acting thereon to open the valve assembly in response to slight decreases in downstream pressure and to cooperate with the biasing springs to close the valve assembly in response to significant increases in downstream pressure.

Abstract: A hose connection vacuum breaker backflow preventing device for installation on the discharge nozzle of a water faucet for preventing reverse water flow into the faucet which may possibly contaminate the water supply. The device includes a unitary tubular body defining an unobstructed passageway with threaded female inlet and male outlet connections at opposite ends thereof. An integral shoulder is formed interiorly of the passageway and a pair of exhaust ports open radially outwardly through the body from the passageway upstream of the shoulder. A valve assembly within the passageway is spring-biased into a seated position closing communication between the inlet and outlet ends of the passageway while permitting fluid communication between the outlet end and the ports for draining any reverse water flow.

Abstract: Backflow preventer apparatus for preventing backflow of fluid in a fluid flow line includes an improved relief valve which drains fluid backflow from a zone between upstream and downstream check valves if the normal flow is shut off and downstream check valve fails to seal drip tight. During normal flow, the relief valve is closed. The relief valve includes a "peel seal" formed by a flexible diaphragm which peels to open the relief valve orifice for backflow therethrough from the downstream check valve to the ambient atmosphere.

Abstract: The present invention is for a freezeless ground hydrant having a nozzle above ground and having a main valve adapted to be connected to an underground source of water pressure at a point located below the frost line in the soil. Also underground is a drain water storage system including a storage cylinder. When the hydrant is turned off, the residual water in the nozzle drains into the cylinder and is retained there until the hydrant is turned on again. When the hydrant is turned on, a mechanical linkage connected to the hydrant handle causes the cylinder to expel the drain water therein through a drain line which extends upwardly above the ground.

Abstract: A vacuum breaker for connection in the discharge line from a source of liquid. The preferred embodiment comprises an elongated body for connection in the discharge line and opening to atmosphere through a lateral passageway selectively closed by a cylindrical sleeve coaxially carried by said body. In the open position of the sleeve the vacuum breaker is particularly adapted for in-line installation in the drain line of appliances. Various applications for the vacuum breaker are disclosed.

Abstract: Apparatus and method of its use for delivering liquid additives to irrigation units which comprises an additive liquid source and means for injecting said additives. Injection means utilize the venturi effect to permit controlled delivery of additive to fluid bound for the sprinkler circuit. Check valves permit connection of one additive liquid source to a series of water supplies. A pressure relief valve having sliding members is also described.

Abstract: A tube separator (1) having a housing (2) with an inlet (5), an outlet (6) and a separating chamber (14) connectable with a drain (9) is provided. A shut-off member (10) connecting the inlet (5) with the outlet (6) in a first position thereof and separating the inlet (5) from the outlet (6) and connecting the outlet (6) with the separating chamber (14) in a second position is provided between the inlet (5) and the outlet (6). In order to prevent the entry of contaminations into the separating chamber (14) and hence into a line system connectable with the inlet (5) and the outlet (6) the separating chamber (14) is designed in a manner to be tightly sealed against contaminations. To this end preferably a filter (24) is provided between the separating chamber (14) and the drain (9).

Abstract: A ball cock and float assembly (10) having a shank portion (11) that is adapted to be insertably received through the inlet opening (13) in the bottom wall (14) of a reservoir tank (12). A support means (50) extends upwardly of the shank portion (11). The support means (50) comprises post means (30) that extend fixedly upwardly from the shank portion (11), and extension means (46) that are telescopically slidable along the post means (30). A lock (42) secures the extension means (46) at a selected position along the post means (30) to provide in gross adjustment in the vertical height of the float assembly (110) that is movable along the extension means (46). A valve (55) is carried by the extension means (46) upwardly of the float means (110). An inlet conduit (52) communicates from the shank portion (11) through the post and extension means (30, 46) to the inlet port ( 54) of the valve means (55).

Abstract: A miniature anti-siphon valve is disclosed which is of inexpensive manufacture, requiring only three parts which may be molded rather than machined. The valve will close to prevent reverse fluid flow when either pressure in the supply line drops below ambient air pressure or fluid flow into the valve outlet occurs. The valve operates regardless of its physical orientation, and in one embodiment may include a nozzle for use with a bidet.

Abstract: This invention relates to a diverter valve with integral atmospheric type vacuum breaker.

Abstract: A flushometer valve integrable with a structure to which it is mounted.

Abstract: The present invention comprises an outer housing and an inner housing having a pressure relief chamber defined therebetween. The inner housing receives fluid and directs it through a pressure outlet opening into the pressure relief chamber. The outer housing includes an outlet opening and a pressure relief opening. A flexible cylindrical seal surrounds the pressure outlet opening of the inner housing and is yieldably movable radially outwardly to a pressure flow position wherein it closes the pressure relief opening of the outer housing and opens the pressure outlet opening of the inner housing.

Abstract: A fill valve for controlling liquid level in a toilet water tank or other tank includes a valve head assembly positioned at a selected level in the tank by a telescoping riser assembly with liquid inlet and outlet conduits extending toward the tank bottom. An adjusting nut on a stationary riser engages thread structures on inlet and outlet conduits for raising or lowering the valve head assembly and adjusting the liquid level. A main valve in the head assembly is controlled by a non-horizontal diaphragm separating a vent chamber and a control chamber. The control chamber is pressurized as liquid rises to the selected level by a standpipe extending downwardly in the tank. The valve closing and opening levels are offset by partly filling the vent chamber with liquid when the main valve is open to hydraulically load the diaphragm. A vacuum breaker valve obstructs backflow through the valve, vents the flow path when the valve is closed, and regulates flow into the vent chamber when the valve is open.

Abstract: A tube separator (1) is provided comprising a shut-off means (4) for separating an inlet side (2) from an outlet side (3) as well as a control valve (11) controlling the shut-off means (4) in dependence on the difference of the pressure at the inlet side 2 and the outlet side 3. In order to prevent a flutter of the shut-off means (4) for low flow rates a valve (42) is provided which is designed such that it releases the connection of the outlet pressure with the control valve (11) only if the flow rate of the medium drops below a certain value.

Abstract: A water flow control valve unit for a washing device of the private parts of a human body using a nozzle spouting water, in which several valves necessary for controlling the water flow to the nozzle are arranged unitedly as a single unit. The changeover valve in the unit has a plurality of longitudinal holes for passing through water and a diaphragm which opens only when water passes through the holes, whereby the water pressure given to the nozzle is maintained at a degree sufficient for washing the private parts of a human body.

Abstract: A relief valve assembly for use in backflow preventers having at least one check valve, the relief valve assembly being operable in response to changes in differential pressure across the check valve and in fluid connection downstream of the check valve for discharging liquid therefrom to atmosphere when a backflow condition occurs. The at least one check valve prevents backflow from a service pipe to the supply pipe but when the at least one check valve is fouled, and a backflow condition occurs, the relief valve assembly operates to permit the discharge of the liquid from the service line and prevent contamination of the supply line.

Abstract: An on/off valve, preferably of the ball type, with an anti-siphon feature. The valve has concentric opposite direction flow with open structured support elements to maintain the inlet tube properly positioned within the elongated housing. A cup-shaped poppet-type float valve prevents fluid from spraying out of air vents upon opening of the ball valve. The control valve is particularly adapted for indoor use.

Abstract: A backflow preventer apparatus designed for connection between a supply pipe having liquid under pressure and a service pipe, the backflow preventer apparatus comprising a pair of check valves in series and defining a zone therebetween, a relief valve operable upon a change in differential pressure across the upstream check valve, and a vacuum breaker operable upon a drop in pressure in the zone to a predetermined pressure supply above atmospheric pressure. The differential pressure operable relief valve, when opened upon certain operating conditions, causing the zone to drain to atmosphere. The vacuum breaker operates independent of supply pipe pressure or service pipe pressure but solely on a drop in pressure in the zone.

Abstract: A backflow-preventing valve for connection between a high-pressure input line and a lower-pressure output line has a valve housing forming upstream and downstream chambers and having an inlet opening into the upstream chamber remote from the downstream chamber, a vent opening into the upstream chamber offset from the inlet, and an outlet opening into the downstream chamber. A check valve in the downstream chamber allows flow only from the upstream chamber into the downstream chamber. A tubular piston sealingly engaged across the upstream chamber upstream of the vent, formed with a throughgoing bore, and having a downstream end engageable with the check valve is movable between an upstream position with its downstream end in the upstream chamber spaced from the check valve and a downstream position with its downstream end engaged sealingly with the check valve.

Abstract: A wall mountable vacuum breaker is disclosed. In one embodiment, there is an escutcheon mountable against the wall over a wall opening, the escutcheon having openings alignable with fluid supply and outlet pipes which terminate near the opening. There are also a pair of couplings connectable to the respective pipes through the escutcheon, with at least one of the couplings being shaped so as to bear against an outwardly facing surface of the escutcheon when the coupling is connected to the pipe. This holds the escutcheon against the wall. A fastener is provided to connect the main valve body to the respective couplings. In an especially preferred embodiment, there is provided a decorative shroud that is removably mounted to the valve body so as to enclose the valve body and the fastener.

Abstract: A liquid flow control valve having a valve seat and a valve plug for engaging said valve seat, said plug being connected to a pressure responsive device, such as a diaphragm, for movement therewith, said control valve being opened and closed by forces acting on opposite sides of said diaphragm, an anti-syphon valve located below said diaphragm for directing air into said flow control valve when a suction occurs at the inlet to said valve seat; said anti-syphon valve comprising an annular array of flaps which control the flow of air through openings in the body of said liquid flow control valve. Said flaps can be arranged to also provide a barrier to reverse flow from the liquid flow control valve exit through said valve seat to its inlet. Said liquid flow control valve can be of the pilot valve operated type or manually operated.

Abstract: A device for mixing and dispensing fluids comprising a head unit having a flow passage provided with a converging portion for receiving a first liquid stream from a pressurized source A hollow pipe rotatably mounted in the head unit is provided with a suction port through which a second liquid may be introduced into the flow passage downstream of the converging portion. The hollow pipe partially projects into the flow passage thereby forming a restriction in the flow passage, a low pressure region thus being formed downstream of the suction port. A chamber may be provided in the flow passage downstream of the converging portion thereof and upstream of the suction port. The chamber is vented to atmosphere thereby providing a vacuum break so as to prohibit the second liquid from being drawn back into the source of the first liquid upon terminating the flow of the first liquid stream.

Abstract: A relief valve assembly for use in backflow preventers having at least one check valve, the relief valve assembly being operable in response to changes in differential pressure across the check valve and in fluid connection downstream of the check valve for discharging liquid therefrom to atmosphere when a backflow condition occurs. The at least one check valve prevents backflow from a service pipe to the supply pipe but when the at least one check valve is fouled, and a backflow condition occurs, the relief valve assembly operates to permit the discharge of the liquid from the service line and prevent contamination of the supply line.

Abstract: A suds return valve for automatic washers is provided in which a flapper valve can be manually set to save suds water for subsequent use, the valve being automatically returned to direct rinse liquid to drain after the suds water has reached a predetermined height in a storage receptacle. The valve can be manually set to use suds water in a wash cycle and the valve would be automatically returned to send water to the drain after a predetermined amount of suds water has been removed from the storage receptacle.

Abstract: A backflow preventer apparatus designed for connection between a supply pipe having liquid under pressure and a service pipe, the backflow preventer apparatus comprising a pair of check valves in series and defining a zone therebetween, a relief valve operable upon a change in differential pressure across the upstream check valve, and a vacuum breaker operable upon a drop in pressure in the zone to a predetermined pressure supply above atmospheric pressure. The differential pressure operable relief valve, when opened upon certain operating conditions, causing the zone to drain to atmosphere. The vacuum breaker operates independent of supply pipe pressure or service pipe pressure but solely on a drop in pressure in the zone.

Abstract: The invention concerns a hydraulic disconnector to separate an inflow circuit from outflow from an outflow circuit.Controlled by the membrane, the valve opens the drainage of chamber if the outflow circuit flows back in the direction of the arrow. The spring opens this drainage even if the membrane is punctured.

Abstract: A water hydrant is provided with a number of valves operable to eliminate freezing problems and to prevent backflow into potable water, thereby precluding the danger of contamination. Water and air valves operate in conjunction such that trapping of water in the hydrant is averted by the admission of air after each closing of the water valve. By a somewhat different arrangement in outlet spout valving, air is also admitted to the spout after each closing of the water valve or other reduction in water pressure, the spout valving having the additional feature of blocking backflow, all of which meets the anti-contamination requirements of the hydrant.

Abstract: A tap for a drainage bag includes a rotatable valve which is adapted to be readily taken apart for cleaning. The valve includes a body, having a cylindrical recess formed therein, and a cylindrical valve member which fits into the cylindrical recess in the body. The body is secured to a flat flange of plastic, which flange is typically welded, or adhesively fixed, in a face-to-face manner to a wall of the bag. The construction method used to make the tap is particularly well suited to rapid mass-production methods of manufacture.

Abstract: A check valve assembly for use in backflow preventer apparatus or the like, the check valve assembly being of the poppet valve type. The assembly includes a body member having a flow passage therethrough with an inlet and an outlet, the body member further having an annular valve seat in said passage and an opening in its wall opposite and coaxial with the valve seat. A tamperproof preloaded valve module is inserted through said opening for coacting with the valve seat and the module is retained in position within the body by a cover plate closing the opening.

Abstract: A device for preventing the back flow of water from a point of use into a water supply line. The device includes a unitary casing having an inlet, a central chamber, an outlet, a removal port and a drain vent opening. The inlet, the central chamber and the outlet are coaxially aligned. A relief valve is located in the central chamber and offset from the coaxial alignment of the inlet, the central chamber and the outlet. There is a cover for the removal port. There is also a pair of check valves. One is mounted between the inlet and the central chamber and the other is mounted between the outlet and the central chamber. The device allows water to pass unobstructed in a straight-through flow path through the device. The back flow of water is prevented.

Abstract: A hose mounted fluid mixing dispenser has a fluid containing bladder inside a bottle. A bottle cap fitting the bottle has a water hose connection, a water passage having a rectilinear portion and a nozzle with an adjustable metering device for introducing fluid from the bladder into the water stream as it passes through the rectilinear portion. A removable plug in the cap permits filling of the bladder. An anti-syphon device is incorporated in the hose connecting portion of the cap. Water fills the space between the bladder and the bottle as the bladder empties, providing a pressure differential to impel fluid into the stream.

Abstract: An anti-siphon selector valve for directing fluid into one of a plurality of lines. The valve includes a valve body having an input port and a plurality of output ports and a U-shaped conduit assembly mounted on the valve body and selectively connectable between the input port and one of the output ports. A movable piston is located in the conduit assembly for sealing the conduit to the valve body. The valve further includes an anti-siphon valve assembly mounted in the U-shaped conduit assembly for venting the output port and the lines to which it is connected to the atmosphere.

Abstract: Two identical check valve assemblies are connected in series with a zone between them. A differential control valve vents this zone to atmosphere whenever the downstream pressure approaches the upstream pressure within a predetermined magnitude. The action of the differential control valve is responsive to differential pressure across the upstream check valve.

Abstract: An improved check valve for a backflow preventing valve of the type having an inlet passage, an intermediate chamber, and an outlet passage, includes a stationary valve port fluidly communicating with the intermediate chamber, a movable contoured valve seat for sealing the port, and a valve closing apparatus in rolling engagement with the valve seat and responsive to the pressure differential thereacross. The valve closing apparatus urges the valve seat to a valve closed position and includes a stationary shaft, a pair of rollers, and a spring. The spring biases the rollers against the contoured valve seat to thereby effect the closure of the seat member against the valve port. An improved exhaust valve is also provided and includes a balanced valve member providing a path between the intermediate chamber and the atmosphere when in a valve open position. The balanced valve member is resiliently biased between a valve seat and a moveable diaphragm.

Abstract: A check valve assembly employs a poppet slidably mounted in a stationary barrel to engage a seat in the barrel. The poppet and barrel cooperate to form a closed chamber containing a spring which acts to close the poppet against the seat, but the force of the spring is partially overcome by a reduction in pressure in the chamber caused by venturi action by forward flow through the check valve assembly with the result that higher upstream pressure is needed to open the valve than to maintain it in open position, at least for low and medium flow rates. Two identical check valve assemblies are connected in series, the assemblies being perpendicular to each other, each mounted at about a 45.degree. angle with respect to coaxial inlet and outlet terminals.

Abstract: Disconnector intended to be inserted in a drinking water distribution system so as to prevent, in the case of a pressure drop for any reason whatsoever, the water which is downstream and may be considered as polluted, from being fed-back upstream beyond the disconnector.The passage of the water through this disconnector from upstream to downstream and the prevention of feedback of polluted water from downstream to upstream are controlled by a hollow piston closed at both its ends slidable between two end positions under the effect of the greater of the upstream or downstream pressures, whose cylindrical wall has therethrough upstream and downstream apertures, in combination with seals whose lips are applied to said cylindrical wall and which according to the position of the piston, allow the water to pass through these apertures or not.

Abstract: An anti-siphon, selector valve for directing fluid into one of a plurality of lines. The valve includes a valve body having an input port and a plurality of output ports and a U-shaped conduit mounted on the valve body and selectively connectable between the input port and one of the output ports. The valve further includes an anti-siphon valve assembly mounted in the U-shaped conduit for venting the output port and the lines to which it is connected to the atmosphere.

Abstract: A self-regulating tide gate is installed on a conduit connecting an open body of water with a protected body of water. The tide gate comprises a mounting plate secured to the conduit at its end in the open body of water, the mounting plate defining an opening into the conduit. A door has its upper edge pivotally mounted at the top of the conduit, a door float is mounted to the door on its edge opposite the hinged edge and counterfloats are mounted to counterfloat arms extending from the door across the pivot axis thereof. When the water is below a critical level at which it is desired that the door close, the door float maintains the lower edge of the door on the surface of the water, thereby maintaining the door open and blocking debris from jamming the mouth of the conduit. As the water level rises, it acts on the counterfloat to pivot the door towards its closed position, whereafter the door is caught in the flow of water entering the conduit and rapidly pivoted to its closed position.

Abstract: A backflow preventer valve including a housing structure having inlet and outlet ports therethrough for attaching to system conduits, a chamber formed in the housing, a pair of spaced valve seats associated with one of the ports including a space formed between the valve seats, a movable valve assembly including a first member hingedly attached to the valve housing structure for movement in the chamber between a closed position adjacent to the valve seats and an open position angularly related to the closed position, the valve assembly having a clapper portion defined by relatively movable inner and outer members, a flexible valve member including first and second portions and separate members for attaching the flexible valve member respectively to the inner and outer clapper members, the first portion of the flexible valve member being engageable with one of the pair of spaced valve seats in the closed position thereof and the second portion being engageable with the other of the pair of valve seats in the c

Abstract: A pair of interlocked flap valves within a faucet, such as a hose bib, provides for a fluid flow from a pressurized source through a discharge outlet while preventing a back flow to the source due to a lower pressure at the source than exists downstream as would occur within a resilient garden hose filled with water, sealed off, and being heated by the sun. A first flap valve, comprising a check valve, automatically closes when the main line pressure drops substantially or completely ceases, or by backflow pressures. When the check valve closes, an interlock connection thereof to a second flap valve, comprising a relief valve, simultaneously opens said relief valve relative to a relief port for outward discharge of the fluid. A manual control knob provides for selective "on-off" operation of the check valve.

Abstract: In a wall hydrant, on the inner and outer ends of a wall-penetrating conduit, an inlet connection casting and a discharge casting; a valving member movable axially in an inlet valving bore relative to a seat; a lateral conduit outlet from a discharge casting bore; a shaft structure including key-rotated stem threaded through a plug in the latter bore end and connected axially to shift, upon rotation, the valving member, and also a shaft-carried flange "O"-ring sealable on an interior surface controlling plug-associated exterior draining and air vent openings; the valving and flange seals being spaced, relative to the controlling surface and inlet bore spacing, for conduit drainage and vent opening after inlet closure; a part of the shaft structure upon removal being invertable to serve as a valve seat service tool. Within the hydrant, an anti water backup device.

Abstract: A back flow preventing device is disclosed which prevents the reverse flow of water from a point of use into a water supply system. The device has a casing with coaxially aligned inlet and outlet openings, and containing coaxially aligned inlet and outlet check valves. The coaxial alignment of the inlet and outlet openings, and of the inlet and outlet check valves serves to minimize the pressure drop through the device. Between the inlet and outlet check valves is a diaphragm actuated relief valve which opens to drain the passage between the check valves if they should malfunction or if there is a drop in the supply line pressure sufficient to cause actual or potential reverse flow back toward the supply line. The internally-located inlet and outlet check valves are each removably secured in place by internally-located retaining rings.

Abstract: Two check valves in series with a zone between them are mounted between the supply pipe and discharge pipe, and a relief valve vents the zone to atmosphere under predetermined pressure conditions in the pipes. A valve poppet in the upstream check valve cooperates with its seat and an enclosing stationary barrel to form a first chamber. A second chamber is formed in the barrel on the other side of the valve poppet, and a third chamber is formed downstream of the valve poppet and the barrel, and constitutes the zone to be vented. An ejector nozzle receives liquid from the first chamber when the valve poppet is open, and discharges it into the zone. The action of the ejector nozzle aspirates the second chamber in the upstream check valve to reduce the pressure drop when the valve is open. The velocity head of the discharge from the ejector nozzle is directed against a valve poppet in the downstream check valve, which also includes a pressure affected piston area.

Abstract: A backflow preventer valve including a housing structure having inlet and outlet ports therethrough for attaching to system conduits, a chamber formed in the housing, a pair of spaced valve seats associated with one of the ports including an air space formed between the valve seats, and a movable valve assembly including a first member hingedly attached to the valve housing for movement in the chamber between a closed position adjacent to the valve seats and an open position angularly related to the closed position, and the valve assembly having a clapper portion defined by relatively movable inner and outer members, a flexible valve member including first and second portions and separate members for attaching the flexible valve member respectively to the inner and outer clapper members, the first portion of the flexible valve member being engageable with one of the pair of spaced valve seats in the closed position thereof and the second portion being engageable with the other of the pair of valve seats in th

Abstract: A liquid supply system in which liquid is only supposed to flow from a high-pressure upstream portion to a low-pressure downstream portion is provided with a backflow preventer and upstream thereof with an isolating valve assembly. The backflow preventer opens completely whenever the pressure upstream of itself drops below a predetermined minimum, thereby draining the conduit downstream of itself to prevent reverse flow in the line. The isolating valve assembly continuously monitors the pressure in the upstream and downstream conduit portions and shuts a cutoff valve between these portions whenever the pressure differential between the two portions falls below a predetermined minimum, while simultaneously depressurizing or draining the downstream portion.

Abstract: Two identical check valves assemblies are connected in series with a zone between them. A differential control valve vents this zone to atmosphere whenever the downstream pressure approaches the upstream pressure within a predetermined magnitude. The action of the differential control valve is responsive to differential pressure across the upstream check valve.

Abstract: A backflow preventer comprising a body defining a passage for flow of liquid between a supply pipe and a service pipe, a check valve in the body passage, and a relief valve assembly connected to the body passage downstream of the check valve, the assembly comprising a liquid drainage passage connected to a first port in the body passage, a first valve in the drainage passage, a gas intake passage connected to a second port above the first port in the body passage, and a second valve in the intake passage.

Abstract: A back flow preventing device which prevents the reverse flow of water from a point of use into a water supply system. The device has a casting with coaxially aligned inlet and outlet openings, and containing coaxially aligned inlet and outlet check valves. The coaxial alignment of the inlet and outlet openings, and of the inlet and outlet check valves serves to minimize the pressure drop through the device. Between the inlet and outlet check valves is a diaphragm actuated relief valve which opens to drain the passage between the check valves if they should malfunction or if there is a drop in the supply line pressure sufficient to cause actual or potential reverse flow back toward the supply line.

Abstract: A backflow preventing valve has a body with two principal portions made of a glass-fiber reinforced plastic. One portion has an inlet port and an outlet port on a through axis, the ports opening to an inlet chamber and an outlet chamber respectively. An intermediate chamber merges with the inlet chamber at an inlet valve seat and also merges with the outlet chamber at an outlet valve seat, the valve axes and the through axis being coplanar. Inlet and outlet poppet valves are urged toward their respective seats by springs in the intermediate and the outlet chambers. There is a vent chamber open to the atmosphere and having a vent valve seat merging with the intermediate chamber. A poppet vent valve has a stem movable in a guide toward and away from the vent valve seat. The stem is abutted by a diaphragm disposed between an outer diaphragm chamber and an inner diaphragm chamber and is pressed by a diaphragm spring in the inner diaphragm chamber.

Abstract: An anti-siphon and back-flow prevention valve having a main valve chamber including air ports, an inlet at its lower end and an outlet at its upper end. Contained within the main valve chamber is a check valve including a check valve seat, through which the flow of liquid in the valve must pass. The check valve seat has a flexible diaphragm which mates with the check valve seat and functions to block any back flow of liquid from the main valve chamber into the inlet. A flexible ring is also contained in the main valve chamber and mates with the air ports to function as an air valve, allowing air to enter the main valve chamber during low pressure conditions down stream from the valve. The check valve and air valve operate independently of each other, responding to the various air and liquid pressures in and around the main valve chamber. Both valves are normally held closed by the force of gravity and static water pressure within the main valve chamber during no-flow conditions.