Flapper check valve

A check valve assembly mounted for engagement with a valve seat, said check valve assembly comprising:

• flapper valve comprising
• a bracket pivotably mounted to the valve seat at a flapper mount location,
• a valve plate mounted to said bracket, said valve plate having an upper angled surface accommodating movement relative to said bracket, and
• a mounting assembly joining said valve plate to said bracket,
• said flapper valve having a first closed position with said valve plate in sealing engagement with the valve seat about a periphery of said valve plate and a second open position spaced from the valve seat, and
• a cam member comprising
• a first lever arm pivotably mounted to the valve seat at a first lever arm mount location and including a first lever surface disposed for moving contact with a first engagement surface of said bracket, said first lever arm further comprising a first biasing means for biasing said first lever surface toward contact with said first engagement surface, and
• a second lever arm pivotably mounted to the valve seat at a second lever arm mount location and including a second lever surface disposed for moving contact with a second engagement surface of said bracket, said second lever arm further comprising a second biasing means for biasing said second lever surface toward contact with said second engagement surface,
• said first lever arm mount location and said second lever arm mount location being equally spaced about a point opposite said flapper mount location.

A backflow preventer comprising:

• a body defining a conduit for flow of fluid between an inlet and an outlet, a first valve and a second valve disposed in sequence in the conduit, the first valve having a first position permitting flow in a first direction and a second position opposing flow in a second direction opposite the first direction, with first means for biasing the first valve toward the second position, and the second valve having a first position permitting flow in the first direction and a second position for opposing flow in the second direction, with second means for biasing the second valve toward the second position,
• said first valve mounted for engagement with a first valve seat, said first valve comprising
• a flapper valve comprising
• a bracket pivotably mounted in a region along a first hemisphere of the valve seat,
• a valve plate mounted to said bracket, said valve plate having an upper angled surface accommodating movement relative to said bracket, and
• a mounting assembly joining said valve plate to said bracket,
• said flapper valve having a first closed position with said valve plate in sealing engagement with the valve seat about said periphery of said valve plate and a second open position spaced from the valve seat, and
• at least one lever arm pivotably mounted in a region along a second hemisphere of the valve seat opposite said first hemisphere and including a lever surface disposed for moving contact with an engagement surface of said bracket, said lever arm including a biasing means for biasing said lever surface toward contact with said engagement surface,
• said second valve mounted for engagement with a second valve seat, said second valve comprising
• a flapper valve comprising
• a bracket pivotably mounted in a region along a first hemisphere of the valve seat,
• a valve plate mounted to said bracket along a region generally spaced from a periphery of said valve plate, and
• a mounting assembly joining said valve plate to said bracket,
• said flapper valve having a first closed position with said valve plate in sealing engagement with the valve seat about said periphery of said valve plate and a second open position spaced from the valve seat, and
• at least one lever arm pivotably mounted in a region along a second hemisphere of the valve seat opposite said first hemisphere and including a lever surface disposed for moving contact with an engagement surface of said bracket, said lever arm including a biasing means for biasing said lever surface toward contact with said engagement surface.