초록 ▼

A check valve or backflow preventer has a valve mechanism mounted to a valve cover for removal and replacement as a unit. The valve clapper is resiliently supported to accommodate variations in tolerance. The valve seat is removably secured within the valve body by compression of a resilient seal ri

A check valve or backflow preventer has a valve mechanism mounted to a valve cover for removal and replacement as a unit. The valve clapper is resiliently supported to accommodate variations in tolerance. The valve seat is removably secured within the valve body by compression of a resilient seal ring to engage opposed walls of the seat and body. A spring pretensioning member facilitates safe replacement and removal of the valve mechanism.

대표청구항 ▼

[ What is claimed is:] [21.] 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 acc

[ What is claimed is:] [21.] 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; anda 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, anda 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.