A backflow assembly including a housing with a passage having at least one check valve positioned therein to permit fluid flow in one direction while preventing fluid flow in the reverse direction. The check valve includes a valve head connected to a stem having an outer surface. A hump extends rad
A backflow assembly including a housing with a passage having at least one check valve positioned therein to permit fluid flow in one direction while preventing fluid flow in the reverse direction. The check valve includes a valve head connected to a stem having an outer surface. A hump extends radially outward from the outer surface of the stem. The stem is guided by a bushing during opening and closing of the valve. The bushing includes at least one retention member that moves along the outer surface of the stem during opening and closing of the valve. The interaction between the retention member and the hump on the outer surface of the stem causes a higher friction loss during opening and closing of the valve than other portions of the outer surface.
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What is claimed is: 1. A backflow preventer, said backflow preventer comprising: a housing having a passage therethough and a valve seat; at least one valve positioned in the passage, said at least one valve resiliently biased for closure with the valve seat to prevent fluid flow in a direction an
What is claimed is: 1. A backflow preventer, said backflow preventer comprising: a housing having a passage therethough and a valve seat; at least one valve positioned in the passage, said at least one valve resiliently biased for closure with the valve seat to prevent fluid flow in a direction and to allow fluid flow in a reverse direction, said at least one valve includes a stem extending from a valve head engaging the valve seat, the stem having an outer surface with a hump extending radially outward from the outer surface along a portion of the outer surface; and a valve guide, said valve guide guides the stem during opening and closing of said at least one valve, said valve guide including a bushing having at least one retention member, said at least one retention member engaging the outer surface of the stem, wherein said hump on the outer surface of the stem causes a higher friction loss during engagement with the at least one retention member than other portions of the outer surface of the stem during opening and closing of said at least one valve. 2. The backflow preventer of claim 1, wherein the friction loss is greater when the at least one retention member engages the hump during opening than during closing of said at least one valve. 3. The backflow preventer of claim 1, wherein the at least one retention member requires at least 1 pounds per square inch of fluid flow to overcome the hump on the outer surface of said stem. 4. The backflow preventer of claim 1, wherein a first valve and a second valve are positioned in the passage. 5. The backflow preventer of claim 4, further comprising a water meter, said water meter having an inlet and an outlet, wherein the inlet is positioned to an upstream side of the first valve and the outlet is positioned to a downstream side of the second valve. 6. The backflow preventer of claim 1, wherein the retention bushing includes a plurality of retention members spaced circumferentially around the retention bushing for engagement with the hump. 7. The backflow preventer of claim 1, wherein the at least one retention member is received in a recess formed in an inner surface of the bushing. 8. The backflow preventer of claim 7, wherein at least one compression member is positioned within the recess and engages the at least one retention member. 9. The backflow preventer of claim 8, wherein the at least one compression member is an o-ring. 10. The backflow preventer of claim 9, wherein the at least one retention member and the at least one compression member are retained in place in the recess formed in the inner surface of the bushing by a retention sleeve on an outer surface of the bushing. 11. The backflow preventer of claim 8, wherein the at least one compression member is a spring. 12. The backflow preventer of claim 11, wherein the at least one retention member and the at least one compression member are retained in place in the recess formed in the inner surface of the bushing by a retention sleeve on an outer surface of the bushing. 13. The backflow preventer of claim 1, wherein a spring biases the at least one valve for closure. 14. The backflow preventer of claim 1, wherein the at least one retention member is a ball. 15. The backflow preventer of claim 14, wherein the ball is made from stainless steel. 16. A backflow preventer, said backflow preventer comprising: a housing having a passage therethrough; at least one valve assembly positioned in the passage to prevent fluid flow in a direction and to allow fluid flow in a reverse direction, said at least one valve comprising: a head; a stem extending from said head, said stem having an outer surface, wherein a portion of the outer surface includes a hump extending radially outward; and a bushing, said bushing guides the stem during opening and closing of said at least one valve, said bushing including at least one retention member, said at least one retention member moves along the outer surface of said stem during opening and closing of said at least one valve. 17. The backflow preventer of claim 16, wherein said at least one retention member is received in a recess formed in an inner surface of said bushing. 18. The backflow preventer of claim 17, wherein side walls defining the recess formed in the inner surface of said bushing are angled in relation to a longitudinal axis of said stem. 19. The backflow preventer of claim 16, wherein said bushing includes a plurality of retention members spaced circumferentially around the bushing. 20. The backflow preventer of claim 16, wherein the hump extending radially outward from the outer surface of said stem is located in close proximity to the head such that a higher pressure is required for the at least one retention member to move over the hump than to move along other portions of the outer surface of said stem. 21. The backflow preventer of claim 20, wherein the pressure for the at least one retention member to move over the hump during opening of the at least one valve is greater than the pressure for the at least one retention member to move over the hump during closing of the at least one valve. 22. The backflow preventer of claim 16, wherein the radial distance of the hump increases and then decreases along the outer surface of said stem away from said head. 23. The backflow preventer of claim 22, wherein the radial distance of the hump increases at a faster rate than it decreases along the outer surface of said stem away from said head. 24. A backflow preventer, said backflow preventer comprising: a housing having a passage therethrough; at least one valve assembly positioned in the passage to prevent fluid flow in a direction and to allow fluid flow in a reverse direction, said at least one valve comprising: a head; a stem extending from said head, said stem having a longitudinal axis and an outer surface, wherein a portion of the outer surface includes a portion having a greater radial distance from the longitudinal axis than other portions of the outer surface; and a bushing, said bushing guides the stem during opening and closing of said at least one valve, said bushing including at least one retention member, said at least one retention member moves along the outer surface of said stem during opening and closing of said at least one valve, wherein greater friction loss results when the at least one retention member moves along the portion of the outer surface having a greater radial distance from the longitudinal axis than along other portions of the outer surface.
Funderburk Robert Vernon ; Price Timothy Duane, Swing-type check valve assembly retained within a valve housing by abutting engagement with a valve cover and a port of.
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