Flush valves

Claim 1

IN A FLUSH VALVE, A HOLLOW BODY HAVING AN INLET AND AN OUTLET THEREIN WITH A VALVE SEAT FORMED AROUND SAID OUTLET, A PISTON IN SAID BODY NORMALLY CLOSING SAID VALVE SEAT AND PROVIDING A PRESSURE CHAMBER ABOVE SAID PISTON, SAID PISTON HAVING A BY-PASS EXTENDING THERETHROUGH FOR PASSAGE OF WATER INTO THE PRESSURE CHAMBER FROM SAID INLET, SAID PISTON HAVING A RELIEF VALVE SEAT THEREIN WITH A RELIEF VALVE NORMALLY CLOSING THE SAME AGAINST THE EGRESS OF WATER FROM SAID PRESSURE CHAMBER, AND MEANS INTERPOSED BETWEEN SAID BY-PASS AND INLET FOR PRECLUDING ENTRY OF SEDIMENTARY DEPOSITS IN SAID BY-PASS TENDING TO CLOG THE SAME, SAID LAST NAMED MEANS COMPRISING A RING-SHAPED MEMBER SURROUNDING SAID PISTON AND A DOUBLE ROW OF SPACED RIBS FORMED BETWEEN SAID MEMBER AND SAID PISTON TO PROVIDE IN EACH ROW A PLURALITY OF WATER PASSAGE GAPS THEREBETWEEN, EACH OF WHICH GAPS IS LESS IN WIDTH BUT GREATER IN AREA THAN THE OPENING IN SAID BY-PASS, SAID BY-PASS BEING POSITIONED IN SAID PISTON BETWEEN THE SAID ROWS OF SPACED RIBS.