Foldable check valve

Claim 1

A CHECK VALVE INCLUDING: A GENERALLY TUBULAR VALVE BODY HAVING UPSTREAM AND DOWNSTREAM ENDS OF SMALLER INNER DIAMETER THAN THE INNER DIAMETER OF THE VALVE BODY BETWEEN SAID ENDS; A GENERALLY PLANAR SEAT EXTENDING TRANSVERSELY ACROSS THE VALVE BODY BETWEEN THE UPSTREAM AND DOWNSTREAM ENDS HAVING AN APERTURE THERETHROUGH SURROUNDED BY A SEATING SURFACE ON THE DOWNSTREAM SIDE OF THE SEAT, THE DISTANCE ACROSS THE APERTURE IN ONE DIRECTION BEING SUBSTANTIALLY EQUAL TO THE INNER DIAMETER OF THE DOWNSTREAM END OF THE BODY, AND THE DISTANCE ACROSS THE APERTURE IN ANOTHER DIRECTION BEING LESS THAN THE INNER DIAMETER OF THE DOWNSTREAM END OF THE VALVE BODY, SAID SEAT ALSO HAVING A MOUNTING PORTION ON THE DOWNSTREAM SIDE THEREOF ADJOINING THE SEATING SURFACE; A VALVE MEMBER OF LARGER TRANSVERSE DIMENSIONS THAN THE INNER DIAMETER OF THE DOWNSTREAM END OF THE VALVE BODY HAVING A MOUNTING PORTION AND A FLAPPER PORTION JOINED BY A RESILIENT HINGE PORTION, WHEREBY THE MOUNTING PORTION AND FLAPPER PORTION MAY BE FOLDED TOWARD ONE ANOTHER FOR INSERTION OF THE VALVE MEMBER THROUGH THE DOWNSTREAM END OF THE BODY; SAID MOUNTING PORTION INCLUDING A RIGID MATERIAL, PLATELIKE REINFORCING PORTION AND RESILIENT SEALING MATERIAL ADAPTED TO SEAL AGAINST THE MOUNTING PORTION OF SAID VALVE SEAT; SAID FLAPPER PORTION INCLUDING A RIGID MATERIAL, PLATELIKE REINFORCING PORTION HAVING TRANSVERSE DIMENSIONS GREATER THAN THE RESPECTIVE DIMENSIONS OF SAID APERTURE TO SPAN ACROSS SAID APERTURE WHEN THE VALVE IS CLOSED; AND MEANS FOR SECURING SAID MOUNTING PORTION OF THE VALVE MEMBER IS SEALED RELATION AGAINST THE MOUNTING PORTION ON THE DOWNSTREAM SIDE OF SAID PLANAR SEAT.