The above objects are satisfied with a check valve made in accordance with the present invention. Generally, the check valve includes a check valve mechanism secured within a check valve body. The check valve body includes a body interior wall spaced away from a central longitudinal axis. CHECK VALVESThe check valve mechanism may be removable from the check valve body or be integrally formed as part of the check valve body. Additionally, the check valve mechanism can be used in a conduit, such as a pipe, which forms the body of the check valve mechanism.

The check valve mechanism permits downstream fluid flow in a conduit such as a pipe. The check valve mechanism includes a valve seat having an interior wall extending therethrough defining an opening for fluid flow. Check ValvesA seal retainer is positioned adjacent to the valve seat and is configured to seal the opening. The valve seat includes a downstream face having a raised lip surrounding the opening. The seal retainer has an upstream face having a seal ring mounted thereon which contacts the raised lip to create a fluid seal between the valve seat and the seal retainer. A linkage between the valve seat and the seal retainer permits displacement between the valve seat and the seal retainer. The linkage includes a stem extending between the valve seat and the seal retainer permitting limited axial displacement between the valve seat and the seal retainer.

The linkage also includes at least two arms extending between the valve seat and the seal retainer. The arms each preferably have a first end pivotally mounted to the seal retainer and a second end contacting the interior wall of the valve seat.Check Valves The arms are preferably resiliently biased to provide a retention force urging the seal retainer into engagement with the valve seat to create a fluid seal therebetween when the downstream fluid flow in the opening is insufficient to overcome the retention force provided by the arms.

The interior wall of the valve seat preferably has a first peripheral surface and a second peripheral surface. The second end of each of the arms preferably contacts the first peripheral surface and the second peripheral surface of the interior wall of the valve seat. The arms preferably provide a greater retention force when the second end of each of the arms is in contact with the second peripheral surface than when in contact with the first peripheral surface. A torsion spring can be provided at the first end of each of the arms to provide the retention force to the arms. The second end of each of the arms can have a roller which contacts the interior wall of the valve seat.

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