Abstract: A reduced pressure backflow preventer includes a body defining a passageway for flow of fluid between a supply pipe and a service pipe; a check valve positioned in the passageway; a relief valve assembly positioned downstream of the check valve; and a stabilization device for delaying opening of the relief valve assembly. In one embodiment, the stabilization device includes a reservoir coupled to the body and configured to release fluid, thereby to delay operation of the relief valve assembly. In another embodiment, the stabilization device includes a charging device for increasing the effective volume of the region at the service side of the check valve, thereby to delay operation of the relief valve assembly.

Abstract: A check valve assembly mounted for engagement with a valve seat includes a flapper valve and a lever arm. The flapper valve includes a bracket pivotably mounted along a first hemisphere of the valve seat, a valve plate mounted to the bracket along a region generally spaced from a periphery of the valve plate, and a mounting assembly adjustably joining the valve plate to the bracket. The flapper valve has a closed position with the valve plate in sealing engagement with the valve seat about the periphery of the valve plate. The lever arm is pivotably mounted to the valve seat along a second hemisphere of the valve seat opposite the first hemisphere. The lever arm includes a lever surface disposed for moving contact with an engagement surface of the bracket and a biasing means for biasing the lever surface toward contact with the engagement surface.

Abstract: A check valve assembly mounted for engagement with a valve seat includes a flapper valve and a lever arm. The flapper valve includes a bracket pivotably mounted along a first hemisphere of the valve seat, a valve plate mounted to the bracket along a region generally spaced from a periphery of the valve plate, and a mounting assembly adjustably joining the valve plate to the bracket. The flapper valve has a closed position with the valve plate in sealing engagement with the valve seat about the periphery of the valve plate. The lever arm is pivotably mounted to the valve seat along a second hemisphere of the valve seat opposite the first hemisphere. The lever arm includes a lever surface disposed for moving contact with an engagement surface of the bracket and a biasing means for biasing the lever surface toward contact with the engagement surface.