Anti-siphon check valve

Claim 1

IN A WATER-CONVEYING VALVE BODY FORMING AN ENCLOSED PASSAGEWAY HAVING AN INLET AND AN OUTLET, SAID PASSAGEWAY HAVING VENT OPENINGS FOR VENTING THE VALVE BODY PASSAGEWAY TO ATMOSPHERE PRESSURE, BACK-FLOW PREVENTING MEANS COMPRISING: AN ELONGATED, SUBSTANTIALLY CYLINDRICAL, OPEN-ENDED VALVE SEAT IN SAID PASSAGEWAY JOINED TO THE VALVE BODY AT THE INLET THEREOF, A SECOND VALVE SEAT SPACED FROM AND COAXIAL THEREOF, A SECOND VALVE SEAT, A DOWNWARDLY EXTENDING TUBULAR MEMBER SUBSTANTIALLY CENTRALLY DISPOSED WITH RESPECT TO SAID SECOND VALVE SEAT, THE LOWER END OF SAID TUBULAR MEMBER TERMINATING AT A POINT ABOVE THE LOWER END OF SAID SECOND VALVE SEAT, A LIGHTWEIGHT, NON-METALLIC VALVE HOLDING ELEMENT BUOYANT IN WATER POSITIONED BETWEEN SAID VALVE SEATS, SAID VALVE HOLDING ELEMENT HAVING A BODY PORTION OF GREATER DIAMETER THAN THAT OF SAID ELONGATED VALVE SEAT, A DOWNWARDLY EXTENDING WALL PORTION JOINED TO SAID BODY PORTION, THE INNER SURFACE OF SAID WALL PORTION TAPERING DOWNWARDLY AND OUTWARDLY FROM THE LOWER SURFACE OF SAID BODY PORTION AND BEING SPACED FROM THE OUTER WALL OF SAID ELONGATED VALVE SEAT WHEN THE VALVE HOLDING ELEMENT IS SEATED THEREON, SAID WALL PORTION HAVING A LENGTH SUCH THAT WHEN THE NON-METALLIC VALVE HOLDING ELEMENT IS MOVED BY THE INITIAL FLOW OF THE WATER THROUGH SAID INLET AWAY FROM SAID ELONGATED VALVE SEAT TOWARD SAID SECOND VALVE SEAT THE LOWER MARGIN OF SAID WALL PORTION WILL AT ALL TIMES DURING MOVEMENT OF THE VALVE HOLDING ELEMENT BE BELOW THE UPPER MARGIN OF SAID ELONGATED VALVE SEAT TO IMPEDE THE FLOW OF WATER AROUND SAID WALL PORTION THEREBY TO PREVENT WATER ENTERING THE VALVE BODY FROM REACHING SAID VENT OPENINGS BEFORE THE VALVE HOLDING ELEMENT IS IN SEATED ENGAGEMENT WITH RELATION TO SAID SECOND VALVE SEAT, MEANS JOINED TO THE LOWER SURFACE OF SAID BODY PORTION AND EXTENDING DOWNWARDLY THEREFROM TO A POINT ABOVE THE LOWER MARGIN OF SAID WALL PORTION, SAID MEANS BEING HOLLOW AND HAVING AN OPENING AT THE LOWER END THEREOF WHEREBY WATER FLOWING INTO SAID INLET OF SAID PASSAGEWAY CAN PASS UPWARDLY INTO THE INTERIOR OF SAID MEANS TO ENHANCE THE FLOATABILITY OF SAID VALVE HOLDING ELEMENT, SAID MEANS FURTHER HAVING UPWARDLY AND OUTWARDLY DIVERGING WALLS TERMINATING AT A POINT AT THE LOWER SURFACE OF SAID BODY PORTION SPACED FROM THE UPPER MARGIN OF THE INNER SURFACE OF SAID WALL PORTION, SAID DIVERGING WALLS OF SAID MEANS IN COOPERATION WITH THE INNER SURFACE OF SAID WALL PORTION SERVING TO SUBSTANTIALLY REDUCE ANY TURBULENCE IN WATER PASSING FIRST UPWARDLY AND THEN DOWNWARDLY THEREAGAINST THROUGH SAID INLET OF SAID VALVE THEREBY TO ACHIEVE A SMOOTH, UNIFORM WATER CURRENT FLOW OF SUBSTANTIALLY ALL WATER FLOW RATES, A RESILIENT VALVE MEMBER REMOVABLY HELD BY SAID MEANS AT THE LOWER SURFACE OF SAID BODY PORTION FOR FORMING A FLUIDTIGHT SEAL WITH SAID ELONGATED VALVE SEAT WHEN THE VALVE HOLDING ELEMENT IS POSITIONED THEREON, MEANS ON THE UPPER SURFACE OF SAID BODY PORTION FOR REMOVABLY RETAINING A SECOND RESILIENT VALVE MEMBER IN SPACED RELATION WITH RESPECT TO SAID UPPER SURFACE OF SAID BODY PORTION, SAID SECOND VALVE MEMBER SERVING TO FORM A FLUID-TIGHT SEAL WHEN SAID VALVE HOLDING ELEMENT IS SEATED THEREON, AND MEANS JOINED TO SAID SECOND MENTIONED MEANS EXTENDING UPWARDLY THEREFROM INTO SAID TUBULAR MEMBER AND HAVING DIMENSIONS SUCH THAT IT CAN MOVE RECIPROCABLY THEREIN, SAID VALVE HOLDING ELEMENT UNDER MINIMAL FORWARD FLUID PRESSURES SUBSTANTIALLY INSTANTANEOUSLY FLOATING BODILY TO A DOWNSTREAM POSITION TO DISTENDEDLY SEAT THE RESILIENT VALVE MEMBER POSITIONED AT THE UPPER SURFACE OF SAID BODY PORTION AGAINST SAID SECOND VALVE SEAT TO SEAL-OFF THE VALVE BODY PASSAGEWAY FROM SAID VENT OPENINGS, AND UNDER ZERO OR BACK PRESSURE TO AN UPSTREAM POSITION TO SEAT THE RESILIENT VALVE MEMBER POSITIONED AT THE LOWER SURFACE OF SAID BODY PORTION AGAINST SAID ELONGATED VALVE SEAT TO VENT THE VALVE BODY PASSAGEWAY TO ATMOSPHERIC PRESSURE.