Swing check backflow preventer

Abstract

A swing check valve for controlling fluid flow, including a valve housing having a port for fluid flow therethrough with a removable cover for accessing an interior of the valve housing. A valve assembly is positioned within the interior of the valve housing for controlling the fluid flow through the valve housing. The valve assembly includes a valve seat in fluid communication with the port and a clapper mounted in the valve housing on a pivotally-mounted rocker arm and moveable between an open position responsive to fluid flow in a flow direction and a closed position sealed against the valve seat responsive to fluid flow in an opposite, backflow direction. A spring is captured in the valve housing by the removable cover without attachment to either the cover or valve housing, and normally urges the clapper into the closed position sealed against the valve seat. A first pivot is carried by the spring and cooperates with a mating interior surface of the cover for permitting unattached pivotal movement of the spring relative to the cover. A second pivot is carried by the spring and cooperates with a mating pivot surface carried on the rocker arm for permitting unattached pivotal movement of the spring relative to the rocker arm whereby the spring is allowed to pivot within the valve housing responsive to movement of the clapper. Also disclosed is an alignment spring mechanism for preventing “heel drag” as the clapper is closing.