초록 ▼

An apparatus and method for automatic disablement of a pressure relief valve used in connection with a backflow preventer in a fire line. A normally open solenoid valve is included in a pressure sampling line, extending from an inlet, or upstream chamber to one side of the pressure relief valve. A w

An apparatus and method for automatic disablement of a pressure relief valve used in connection with a backflow preventer in a fire line. A normally open solenoid valve is included in a pressure sampling line, extending from an inlet, or upstream chamber to one side of the pressure relief valve. A water flow switch, interconnected to a power supply and the solenoid valve, is provided in the fire line. In response to water flowing through the fire line, the switch conducts, actuating the solenoid to a closed position. The solenoid thereby hydraulically isolates the inlet sensor line leading to the pressure relief valve. By maintaining high pressure in this portion of the sensor line, the pressure relief valve is effectively disabled. Thus, even if a check valve malfunction occurs, the pressure relief valve will not open and cannot cause a catastrophic loss of water pressure in the fire line.

대표청구항 ▼

In a backflow preventer within a water line, the preventer including a housing having an upstream check valve and a downstream check valve transversely positioned therein, the upstream check valve defining an upstream chamber and an intermediate chamber, and the downstream check valve further defini

In a backflow preventer within a water line, the preventer including a housing having an upstream check valve and a downstream check valve transversely positioned therein, the upstream check valve defining an upstream chamber and an intermediate chamber, and the downstream check valve further defining a downstream chamber, an apparatus for automatically disabling a pressure relief valve hydraulically connected across the upstream check valve between the upstream chamber and the intermediate chamber of the backflow preventer, said apparatus comprising: a. water flow detector means, producing an output signal when water flows through the water line at a predetermined rate; and, b. normally open electro-mechanical valve means on an upstream side of the pressure relief valve, said valve means closing in response to said output signal and hydraulically isolating the pressure relief valve from the upstream chamber.