Disc valve

Claim 1

A FLAPPER VALVE COMPRISING, IN COMBINATION WITH AN ANNULAR VALVE SEAT, A CIRCULAR VALVE BODY OF RESILIENTLY FLEXIBLE MATERIAL HAVING A PERIPHERAL SEALING LIP, MEANS MOUNTING SAID VALVE BODY ON ONE SIDE OF SAID SEAT WITH SAID LIP URGED INTO SEALING ENGAGEMENT WITH SAID SEAT, A DIAMETRAL GROOVE EXTENDING COMPLETELY ACROSS SAID VALVE BODY IN THE SIDE THEREOF OPPOSITE SAID SEAT, SAID GROOVE PROVIDING A BODY PORTION OF SUBSTANTIALLY UNIFORM REDUCED THICKNESS EXTENDING COMPLETELY ACROSS SAID VALVE BODY, AND A SUPPORTING WEB ACROSS SAID SEAT IN BACK-UP RELATION TO SAID REDUCED BODY PORTION, SAID VALVE BODY MOUNTING MEANS COMPRISING ANCHOR LUG MEANS EXTENDING FROM SAID REDUCED THICKNESS BODY PORTION ON THE WEB SIDE THEREOF, SAID LUG MEANS ENGAGING SAID WEB AND ORIENTING SAID BODY PORTION WITH RESPECT THERETO, SAID ANCHOR LUG MEANS DEFINING HINGE AXES IN SAID REDUCED THICKNESS BODY PORTION AND COEXTENSIVE THEREWITH ABOUT WHICH THE OPPOSITE HALVES OF SAID BODY FOLD RELATIVELY EASILY UPON OPENING MOVEMENT OF SAID VALVE IN RESPONSE TO FLOW IN ONE DIRECTION, AND SAID SUPPORTING WEB BEING SUBSTANTIALLY AS WIDE AS SAID GROOVE AND SUBSTANTIALLY COEXTENSIVE THEREWITH FOR SUPPORTING SAID REDUCED THICKNESS BODY PORTION AGAINST REVERSE FLOW.