Differential loading fluid check valve

A differential loading fluid check valve comprising:

• a. a valve body for the passage of fluid, including an inlet port, an outlet port, a chamber intermediate said ports, a service port in communication with said chamber, and a removable cover over said service port, giving selective access to said chamber;
• b. a base, having an inlet side, an outlet side, and an aperture extending therethrough, and further including means for mounting said base transversely within said chamber, for the flow of fluid through said aperture;
• c. a clapper having a proximal edge and an opposing distal edge;
• d. first means for pivotally mounting said proximal edge of said clapper about a first axis, said first means being located on said outlet side of said base adjacent said aperture for movement of said clapper from a closed position over said aperture to an open position at least partially uncovering said aperture;
• e. a cam arm, having a fixed end, a movable end, and a cam surface therebetween for engagement with said distal edge of said clapper;
• f. second means for pivotally mounting said fixed end of said cam about a second axis parallel to said first axis, said second means being located on said outlet side of said base across said aperture from said first pivot means for movement of said cam arm from a closed position to an open position;
• g. means for biasing said cam arm toward a closed position, said biasing means being overcome by a predetermined amount of pressure from fluid flowing through said aperture, and thereafter differentially loading said clapper in response to increasing flow rate.

A differential loading fluid check valve comprising:

• a. a valve body for the passage of fluid including an inlet port, an outlet port, a chamber intermediate said ports, a service port in communication with said chamber and a removable cover over said service port, giving selective access to said chamber;
• b. an upstream check valve subassembly and a downstream check valve subassembly, each of said subassemblies including:
• i. a base having an inlet side, an outlet side, and an aperture extending therethrough;
• ii. a clapper having a proximal edge and an opposing distal edge;
• iii. first means for pivotally mounting said proximal edge of said clapper about a first axis, said first means being located on said outlet side of said base adjacent said aperture, for movement of said clapper from a closed position over said aperture to an open position at least partially uncovering said aperture;
• iv. a cam arm, having a fixed end, a movable end, and a cam surface therebetween for engagement with said distal edge of said clapper;
• v. second means for pivotally mounting said fixed end of said cam about a second axis parallel to said first axis;
• said second means being located on said outlet side of said base across said aperture from said first pivot means for movement of said cam arm from a closed position to an open position;
• vi. means for biasing said cam arm toward a closed position, said biasing means being overcome by a predetermined amount of pressure from fluid flowing through said aperture, and thereafter differentially loading said clapper in response to increasing flow rate;
• c. means for mounting said base of said upstream check valve subassembly transversely within an upstream portion of said chamber, for the flow of fluid through said aperture of said upstream check valve subassembly;
• d. means for mounting said base of said downstream check valve subassembly transversely within a downstream portion of said chamber, for flow of fluid through said aperture of said downstream check valve subassembly.