Check valve

Claim 1

A CHECK VALVE COMPRISING: A BODY INCLUDING AN INLET, AN OUTLET, AN ANNULAR SEAT FORMED BETWEEN SAID INLET AND SAID OUTLET, A RADIALLY INWARDLY EXTENDING FLANGE FORMED UPSTREAM OF SAID ANNULAR SEAT; A GENERALLY CIRCULAR SEAL MEMBER COMPRISING A CONCAVE PORTION HAVING AN UPSTREAM SIDE, A DOWNSTREAM SIDE, AND A PERIPHERY MOUNTED FOR SEALING ENGAGEMENT AGAINST SAID SEAT IN A CLOSED CONDITION OF THE VALVE, AT LEAST A PORTION OF SAID PERIPHERY BEING MOUNTED FOR TORSIONAL FLEXURE IN ONE DIRECTION ONLY AWAY FROM SAID SEAT DURING THE OPENING OF THE VALVE, THE CONCAVE PART OF SAID CONCAVE PORTION OPENING TOWARD SAID OUTLET, A FIRST ELONGATED PORTION EXTENDING LONGITUDINALLY OUTWARDLY FROM THE UPSTREAM SIDE OF SAID CONCAVE PORTION, SAID FIRST ELONGATED PORTION HAVING A AXIALLY EXTENDING RECESS FORMED THEREIN AND A REDUCED DIAMETER PORTION FORMED ADJACENT THE UPSTREAM SIDE OF SAID CONCAVE PORTION, AND A SECOND ELONGATED PORTION EXTENDING OUTWARDLY FROM THE DOWNSTREAM SIDE OF SAID CONCAVE PORTION; AND SEAL MEMBER RETAINING MEANS FOR CONFINING A PORTION OF SAID FIRST ELONGATED PORTION TO PREVENT, DURING OPERATION OF THE VALVE, MOVEMENT OF THE FIRST ELONGATED PORTION OF SAID SEAL MEMBER IN AN AXIAL DIRECTION, SAID SEAL MEMBER RETAINING MEANS COMPRISING AN ANNULAR MEMBER INCLUDING A RADIALLY INWARDLY AND RADIALLY OUTWARDLY EXTENDING FLANGE PORTION FORMED ADJACENT THE DOWNSTREAM SIDE OF SAID SEAL RETAINING MEANS, SAID RADIALLY OUTWARDLY EXTENDING FLANGE OF SAID RETAINING MEANS BEING DISPOSED IN ABUTTING ENGAGEMENT AGAINST THE RADIALLY INWARDLY EXTENDING FLANGE OF SAID BODY, SAID RADIALLY INWARDLY EXTENDING FLANGE PORTION OF SAID RETAINING MEANS BEING DISPOSED IN CONTACTING ENGAGEMENT ABOUT SAID REDUCED DIAMETER PORTION FORMED ON SAID FIRST ELONGATED PORTION THEREBY RESTRICTING AXIAL MOVEMENT OF SAID SEAL MEMBER RELATIVE TO SAID SEAL MEMBER RETAINING MEANS DURING OPERATION OF THE VALVE; SAID SEAL MEMBER BEING CONSTRUCTED FOR REMOVAL FROM SAID SEAL MEMBER RETAINING MEANS UPON APPLICATION OF A PREDETERMINED TENSILE FORCE ALONG SAID SECOND ELONGATED PORTION TO CAUSE THE PART OF SAID FIRST ELONGATED PORTION DISPOSED UPSTREAM OF THE RADIALLY INWARDLY EXTENDING FLANGE OF SAID SEAL MEMBER RETAINING MEANS TO MOVE IN A DOWNSTREAM DIRECTION PAST SAID RADIALLY INWARDLY EXTENDING FLANGE OF SAID SEAL MEMBER RETAINING MEANS; SAID ANNULAR SEAT AND SAID SEAL MEMBER RETAINING MEANS COOPERATING TO PROVIDE SUPPORT TO UPSTREAM SURFACE PORTIONS OF SAID SEAL MEMBER TO PREVENT INTERRUPTION OF SEALING CONTACT BETWEEN THE SEAL MEMBER AND THE ANNULAR SEAT WHEN THE OUTLET PRESSURE GREATLY EXCEEDS THE INLET PRESSURE.