Check valve and backflow preventer

A valve element biasing mechanism comprising:

• a base,
• a swing arm having a first end and a second end, said first end hingedly attached to said base,
• a valve element attached at said second end of said swing arm and defining a seal surface,
• a spring, having a first point of attachment and a second point of attachment, said spring, by deflection between said first point of attachment and said second point of attachment, causing a predetermined bias force to be applied in opposition between said swing arm and said base, said predetermined bias force hingedly biasing said seal surface of said valve element in a first bias direction toward sealing engagement with an annular seat seal surface of a valve seat, and
• a pretensioning member having a first end, a second end, a first attachment of said first end of said pretensioning member to said base and a second attachment of said second end of said pretensioning member to said swing arm, said pretensioning member being adjustable relative to at least one of said first attachment and said second attachment to define a controllable length between said first attachment and said second attachment, adjustment of said controllable length being selected to bias said valve seal surface in a second bias direction with said predetermined bias force.

A check valve comprising:

• a valve housing defining a passageway for flow of fluid therethrough between an inlet and an outlet, a chamber region of said passageway disposed between said inlet and said outlet, a valve bore between said inlet and said chamber region, an access opening to said chamber region, and a valve seat with an annular valve seat seal surface in said valve bore;
• a valve housing cover removably securing said access opening to said chamber region;
• a valve element defining a valve element seal surface pivotally mounted within said valve housing for movement between a first position in sealing engagement with said valve seat for resisting flow of fluid between said inlet and said outlet of said passageway, and a second position removed from said valve seat to allow flow of fluid between said inlet and said outlet;
• and
• a valve element biasing mechanism supporting said valve element, said valve element biasing mechanism and said valve element mounted to said valve cover housing, with said valve element biased in a first direction toward said first position;
• said valve housing cover, said valve element biasing mechanism and said valve element being removable from said valve housing and replaceable as a unit;
• said valve element biasing mechanism further comprising:
• a base;
• a swing arm having a first end and a second end, said first end hingedly attached to said base and said second end attached to said valve element,
• a spring, having a first point of attachment and a second point of attachment, said spring, by deflection between said first point of attachment and said second point of attachment, causing a predetermined bias force to be applied in opposition between said swing arm and said base, said predetermined bias force hingedly biasing said seal surface of said valve element in a first bias direction toward sealing engagement with an annular seat seal surface of a valve seat, and
• a pretensioning member having a first end, a second end, a first attachment of said first end of said pretensioning member to said base, and a second attachment of said second end of said pretensioning member to said swing arm, said pretensioning member being adjustable relative to at least one of said first attachment and said second attachment to define a controllable length between said first attachment and said second attachment, adjustment of said controllable length selected to bias said valve seal surface in a second bias direction with said predetermined bias force.

A check valve comprising:

• a valve housing defining a passageway for flow of fluid therethrough between an inlet and an outlet, a chamber region of said passageway disposed between said inlet and said outlet, a valve bore between said inlet and said chamber region, an access opening to said chamber region, and a valve seat with an annular valve seat seal surface in said valve bore;
• a valve housing cover removably securing said access opening to said chamber region;
• a valve element defining a valve element seal surface pivotally mounted within said valve housing for movement between a first position in sealing engagement with said valve seat for resisting flow of fluid between said inlet and said outlet of said passageway, and a second position removed from said valve seat to allow flow of fluid between said inlet and said outlet;
• a valve element biasing mechanism supporting said valve element, said valve element biasing mechanism and said valve element mounted to said valve cover housing, with said valve element biased in a first direction toward said first position;
• a valve seat seal assembly comprising:
• a valve seat ring removably positioned within said valve bore defined by said valve housing, said valve seat ring having an external circumferential surface, an external circumferential shoulder and axial annular sealing surface;
• a valve seal ring comprised of a resilient deformable material, positioned within said bore of said valve housing and about said circumferential surface for engagement with said external circumferential shoulder;
• a seal clamp ring positioned about said circumferential surface and within said bore of said valve housing to engage said valve seal ring on a side of said valve seal ring opposite said external circumferential shoulder;
• and
• fastener elements releasably engaged between said valve seat ring and said seal clamp ring, said fastener elements applying a force across said valve seat ring and said seal clamp ring to cause said resilient material of said seal ring to deform into sealing and securing engagement between a surface of said valve seat ring and an internal circumferential surface of said bore of said valve housing;
• said valve housing cover, said valve element biasing mechanism and said valve element being removable from said valve housing and replaceable as a unit.

A backflow preventer comprising:

• a valve housing defining a passageway for flow of fluid therethrough between an inlet and an outlet, a first chamber region and a second chamber region of said passageway disposed in sequence between said inlet and said outlet, a first access opening to said first chamber region and a second access opening to said second chamber region, a first valve bore between said inlet and said first chamber region and a second valve bore between said first chamber region and said second chamber region, and a first valve seat in said first valve bore and a second valve seat in said second valve bore;
• a first valve housing cover removably securing said first access opening to said first chamber region, and a second valve housing cover removably securing said second access opening to said second chamber region;
• a first valve element defining a valve element seal surface pivotally mounted within said valve housing for movement between a first position in sealing engagement with said first valve seat seal assembly for resisting flow of fluid through said passageway, between said inlet and said outlet of said passageway, and a second position removed from said first valve seat seal assembly, and a second valve element defining a second valve element seal surface pivotally mounted within said valve housing for movement between a first position in sealing engagement with said second valve seat seal assembly for resisting flow of fluid through said passageway, between said inlet and said outlet of said passageway, and a second position removed from said second valve seat seal assembly, said first valve element and said second valve element in their respective said second positions allowing flow of fluid through said passageway between said inlet and said outlet;
• and
• a first valve element biasing mechanism supporting said first valve element, said first valve element biasing mechanism and said first valve element mounted to said first valve cover housing, with said first valve element biased toward its said first position, and a second valve element biasing mechanism supporting said second valve element, said second valve element biasing mechanism and said second valve element mounted to said second valve cover housing, with said second valve element biased toward its said first position;
• each of said first valve element biasing mechanisms and said second valve biasing mechanisms further comprising:
• a base;
• a swing arm having a first end and a second end, said first end hingedly attached to said base and said second end attached to said respective valve element,
• a spring, having a first point of attachment and a second point of attachment, said spring, by deflection between said first point of attachment and said second point of attachment, causing a predetermined bias force to be applied in opposition between said swing arm and said base, said predetermined bias force hingedly biasing said seal surface of said respective valve element in a first bias direction toward sealing engagement with an annular seat seal surface of a valve seat, and
• a pretensioning member having a first end, a second end, a first attachment of said first end of said pretensioning member to said base, and a second attachment of said second end of said pretensioning member to said swing arm, said pretensioning member being adjustable relative to at least one of the first attachment and second attachment define a controllable length between said first attachment and said second attachment, adjustment of said controllable length selected to bias said valve seal surface in a second bias direction with said predetermined bias force;
• said first valve housing cover, said first valve element biasing mechanism and said first valve element being removable from said valve housing and replaceable as a first unit, and said second valve housing cover, said second valve element biasing mechanism and said second valve element being removable from said valve housing and replaceable as a second unit.