Check valves

Claim 1

A CHECK VALVE STRUCTURE COMPRISING A HOUSING HAVING AN ANNULAR FLANGE PROVIDED WITH A CHAMBER THEREIN AND AN OUTLET NIPPLE COMMUNICATING WITH SUCH CHAMBER, SAID FLANGE HAVING AN ANNULAR FREE EDGE PORTION ENGAGEABLE AGAINST AN APERTURED WALL OF A RECEPTACLE AND PROVIDED WITH AN ANNULAR CHANNEL, A RESILIENT VALVE ELEMENT PROVIDED WITH A PERIPHERAL BEAD SHAPED TO FIT IN SAID CHANNEL AND HAVING A SURFACE SUBSTANTIALLY FLUSH WITH SAID FREE EDGE PORTION OF SAID FLANGE AND ENGAGEABLE AGAINST THE WALL OF RECEPTACLE TO FORM A SEAL BETWEEN SAID FLANGE AND SAID WALL, SAID VALVE ELEMENT HAVING AN AXIAL OPENING THERETHROUGH AND BEING FORMED AT ONE SIDE SURROUNDING SUCH OPENING WITH AN INTEGRAL ANNULAR THINEDGED LIP ENGAGEABLE AGAINST THE WALL OF THE RECEPTACLE, THE APERTURES IN SUCH WALL BEING RADIALLY OUTWARDLY OF SAID LIP, AN ANNULAR REINFORCING RIB FORMED INTEGRAL WITH SAID VALVE ELEMENT AT THE SIDE THEREOF OPPOSITE SAID LIP AND OF LARGER DIAMETER THAN SUCH LIP, SAID RIB AND SAID LIP COMBINING TO FORM A RELATIVELY THICK ANNULAR RADIALLY INWARD PORTION OF SAID VALVE ELEMENT TO LEND SUBSTANTIAL STIFFNESS THERETO, SAID VALVE ELEMENT BETWEEN SAID RIB AND SAID BEAD HAVING A RELATIVELY THIN HIGHLY FLEXIBLE PORTION TO PROVIDE FOR FREE MOVEMENT OF SAID LIP TOWARD AND AWAY FROM SAID WALL, SAID BEAD BEING THICKER THAN SAID FLEXIBLE PORTION OF SAID VALVE ELEMENT TO BE RETAINED IN POSITION BY SAID CHANNEL.