Flushing valves

Claim 1

A FLUSHING VALVE FOR A LIQUID OF THE TYPE COMPRISING A CYLINDRICAL VALVE HAVING A PISTON CHAMBER AND WITH AN INLET ON ONE SIDE AND AN AXIAL OUTLET; A HOLLOW PISTON IN SAID CHAMBER CARRYING A MAIN VALVE CONTROLLING THE SAID OUTLET, SID PISTON BEING SUBJECTED TO THE PRESSURE IN SAID INLET AND ARRANGED TO BIAS SAID MAIN VALVE TO OPEN POSITION BY THE INLET PRESSURE AND HOUSING A SPRING-SEATED RELIEF VALVE CONTROLLING THE PASSAGE OF LIQUID FROM THE UPPER SIDE OF THE PISTON TO SAID OUTLET; BY-PASS MEANS FOR ENABLING THE PRESSURE OF THE INLET LIQUID TO LEAK TO THE UPPER SIDE OF THE PISTON TO CLOSE THE MAIN VALVE; AND AN ACTUATING DEVICE INCLUDING AN EXTERIOR TILTABLY MOUNTED HANDLE FOR UNSEATING THE RELIEF VALVE WHEREBY THE PRESSURE ON THE UPPER SIDE OF THE PISTON IS LIBERATED TO THE SAID OUTLET AND THEREBY THE INLET PRESSURE CAUSES THE PISTON TO RISE AND OPEN THE MAIN VALVE, WHICH REMAINS OPEN TO DELIVER LIQUID OR PERMIT A FLUSH FOR A PERIOD WHICH DEPENDS UPON THE TIME TAKEN FOR THE PRESSURE ON THE UPPER SIDE OF THE PISTON TO BE REESTABLISHED THROUGH THE BYPASS MEANS AND THEREBY TO CAUSE THE RETURN OF THE PISTON TO CLOSE THE MAIN VALVE; WHEREIN, THE SAID RELIEF VALVE HAS A STEM PROVIDED WITH A TELESCOPIC EXTENSION AND A SPRINGCONTROLLED PLUNGER ROD PROJECTING INTO THE VALVE CASING IN A TRANSVERSE DIRECTION, IS ARRANGED TO BE MOVED AXIALLY BY THE EXTERIOR TILTABLY MOUNTED HANDLE TO CAUSE ITS INNER END TO ENGAGE SUCH TELESCOPIC EXTENSION AND DEFLECT IT AND CONSEQUENTLY THE RELIEF VALVE, SUCH THAT WHEN THE HANDLE IS HELD IN ITS OPERATIVE POSITION THE PISTON WILL RISE UNTIL THE LOWER END OF THE TELESCOPIC EXTENSION SLIDES PAST THE INNER END OF THE PLUNGER, THEREBY TO BECOME DISENGAGED TO PERMIT THE RELIEF VALVE TO CLOSE, AND MEANS INCLUDING A SINGLE ADJUSTMENT SCREW MEANS OPERABLE UPON ACTUATION FROM THE EXTERIOR OF THE CASING TO DIRECTLY EFFECT THE ADJUSTMENT OF THE PLUNGER ROD TO A SELECTED POSITION WITHIN A GIVEN RANGE IN WHICH THE PLUNGER ROD IS TILTED WITH RESPECT TO THE AXIS OF THE TELESCOPIC EXTENSION, SO THAT THE POINT AT WHICH SUCH TELESCOPIC EXTENSION IS RELEASED FROM ENGAGEMENT WITH THE INNER END OF THE PLUNGER ROD WHEN THE HANDLE IS HELD IN ITS OPERATIVE POSITION CAN BE VARIED AND CONSEQUENTLY THE DISTANCE WHICH THE PISTON WILL TRAVEL TOWARDS THE CLOSED END OF ITS CHAMBER, BEFORE IT REVERSES ITS DIRECTION OF TRAVEL AND COMMENCES TO CLOSE, WHEREBY THE DURATION AND EXTENT OF THE FLUSHING OPERATION CAN BE VARIED.