Water-saving flush valve

Claim 1

A FLUSH VALVE FOR A WATER TANK HAVING SIDE AND BOTTOM WALLS COMPRISING: (A) A VALVE ASSEMBLY INCLUDING AN ELONGATED TUBE A SKIRT ATTACHED TO THE TUBE NEAR ITS LOWER END AND INCLUDING AN OUTWARDLY EXTENDING RING-LIKE WALL AND A CYLINDRICAL WALL EXTENDING DOWNWARDLY FROM THE OUTER PART OF SAID RING-LIKE WALL AND HAVING AN ANNULAR OUTWARDLY EXTENDING FLANGE AT ITS LOWER EDGE, SAID SKIRT BEING OPEN AT THE LOWER END AND DEFINING AN ANNULAR CHAMBER AROUND THE TUBE, SAID TUBE AND SKIRT BEING COMPOSED OF MATERIAL HAVING A SPECIFIC GRAVITY OF APPROXIMATELY 1, (B) A SPUD TO EXTEND THROUGH THE BOTTOM WALL OF THE TANK AND HAVING AN ANNULAR VALVE SEAT AT ITS UPPER END AND DISPOSED ABOVE THE INNER SURFACE OF SAID BOTTOM WALL, THE UPPER SURFACE OF SAID SEAT EXTENDING OUTWARDLY AND DOWNWARDLY, AND (C) A RESILIENT DISC CLOSING THE OPEN END OF THE CHAMBER, SAID DISC HAVING AN INNER CYLINDRICAL PORTION AROUND AND ENGAGING THE TUBE AND AN OUTER PERIPHERAL PORTION IN THE FORM OF A FLANGE PROVIDING A GROOVE OPEN ON THE SIDE FACING SAID TUBE, THE OUTWARDLY EXTENDING FLANGE ON THE SKIRT EXTENDING INTO SAID GROOVE AND SERVING TO RETAIN THE DISC IN ASSEMBLED POSITION WITH THE SKIRT, SAID DISC HAVING A DOWNWARDLY AND OUTWARDLY INCLINED ANNULAR FLANGE POSITIONED FOR ENGAGEMENT OF ITS INNER SURFACE WITH THE SAID ANNULAR SURFACE OF SAID SEAT AND HAVING A PLURALITY OF OPENINGS INTO THE CHAMBER WITHIN SAID FLANGE, THE AREA OF THE TOP SURFACE OF THE SKIRT BEING GREATER THAN THE AREA OF THE DISC OUTSIDE OF SAID FLANGE.