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. There is a first passage extending through the two body portions between the inlet chamber and the outer diaphragm chamber and a second passage extending through the two body portions between the intermediate chamber and the inner diaphragm chamber.
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.
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. The diaphragm compares the inlet passage and intermediate chamber pressures and maintains the valve closed when the inlet passage pressure is greater than the intermediate chamber pressure, while moving to absorb fluid displacements from the intermediate chamber caused by large reductions in the inlet passage pressure.
5129416 - Anti-siphon frost-proof water hydrant - Owned by Watts Regulator Company (No. Andover, MA) [*] Notice:The portion of the term of this patent subsequent to July 9, 2008 has been disclaimed.
A water hydrant defines an elongated flow passage having a water inlet and an air inlet, and a laterally extending water outlet spout disposed therebetween to define an outlet. An elongated rotatable stem is reciprocated within the flow passage, and terminates in an exterior handle. A water inlet valve is connected to the stem for control of flow from the water inlet into the passage and an air valve is connected to the stem to control inflow of air and preclude outflow of water through the air inlet. A first check valve in the spout precludes backflow of water into the passage, movement of the air valve opening the first check valve during operation of the handle. A second check valve in the spout downstream of the first check valve precludes backflow of water into the spout. A drain orifice, open to the atmosphere, extends through the spout between the check valves.
A water hydrant defines an elongated flow passage having a water inlet and an air inlet, and a laterally extending water outlet spout disposed therebetween to define an outlet. An elongated rotatable stem is reciprocated within the flow passage, and terminates in an exterior handle. A water inlet valve is connected to the stem for control of flow from the water inlet into the passage and an air valve is connected to the stem to control inflow of air and preclude outflow of water through the air inlet. A first check valve in the spout precludes backflow of water into the passage, movement of the air valve opening the first check valve during operation of the handle. A second check valve in the spout downsteam of the first check valve precludes backflow of water into the spout. A drain orifice, open to the atmosphere, extends through the spout between the check valves.
A double check valve reduced pressure backflow preventor assembly is configured to have a relatively small length, volume and/or weight. The assembly defines parallel, preferably coaxial, inlet and outlet directions. In one aspect, first and second check valves are at an angle, preferably of 90.degree., to the in-line axis and preferably intersect the in-line axis. In one aspect, a relief valve is positioned spaced from the in-line axis. First and second shutoff valves are enclosed in the same integral, unitary housing which encloses the check valves and, preferably, some or all of the relief valve. The shutoff valves are preferably positioned along the in-line axis.
