Abstract: A flush valve for releasing a predetermined volume of liquid upon actuation thereof includes a valve housing having an inlet, an outlet, a valve seating surface circumventing the inlet and a piston housing portion adjacent to the outlet. The piston is movable between an opened and a closed position and has one end sealable with the valve seating surface when the piston is in the closed position to block the flow of liquid from the inlet to the outlet. Upon actuation of the valve, the piston is unsealed from the seating surface to permit liquid to flow from the inlet to the outlet. The other end of the piston is sealed to the piston housing portion and a control chamber is provided having an expanding portion between the piston and the piston housing portion. Restricted flow of liquid from the control chamber to the outlet is permitted.

Abstract: This invention relates to an in-line back flow preventer valve for fluid supply lines of the reduced pressure zone type. The valve body has an inlet means and a discharge means for liquid flow therethrough. A first chamber, within the valve body, is in liquid communication with the valve inlet, with the first chamber having at least one outlet positioned in the periphery thereof. At the outer periphery of the first chamber is a first flexible member which is adapted to seal the peripheral outlet through elastic pressure under the static or back flow pressure condition within the valve. A second chamber commonly referred to as a reduced pressure zone is positioned outside the first chamber and has at least one outlet in the periphery thereof. Mounted at the outer periphery of the second chamber is a second flexible member adapted to seal the peripheral opening through elastic pressure when the valve is under the back flow or static pressure condition.