Image Number 4 for United States Patent #5553333.
An apparatus for flushing a water closet bowl includes a pressurizable reservoir, within which is formed a primary and a secondary pressure zone. Formed at the bottom of the reservoir is an exit aperture through which the pressurized fluid is discharged into the bowl. Movably disposed within the reservoir is an elongate piston member. Formed at the top of the piston member is a hollow cup, which is movably disposed within a downwardly extending hollow cylinder within which is formed the secondary pressure zone. Formed at the bottom of the piston is a plug which seals the exit aperture. During a flushing action, pressure within the secondary pressure zone is released by operating a flushing lever, and the piston moves upwardly so as to release the plug from the exit aperture. In one embodiment, the flushing apparatus includes a fluid inlet regulator that controls the amount of fluid that is introduced into the reservoir from a fluid supply line. The inlet regulator also includes a back flow prevention mechanism which prevents fluid from reentering the fluid supply line in the event of a negative pressure therein. In another embodiment the flushing apparatus includes an overpressure protection mechanism formed within the piston.