Apparatus and method for automatically disabling pressure relief valve of backflow preventer

In a water line backflow preventer, 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, and further including a pressure relief valve having a first sensing line in communication with the upstream chamber and having a second sensing line in communication with the intermediate chamber, the improvement comprising:

• a. a water flow detector, producing an output signal when a predetermined rate of flow through the water line is detected;
• b. a normally open solenoid valve, located within said first sensor line and interconnected to said water flow detector, said solenoid valve closing in response to said output signal and hydraulically isolating the pressure relief valve from the upstream chamber.

In a water line backflow preventer having a housing with an upstream check valve and a downstream check valve transversely positioned therein, the upstream check valve defining an upstream chamber and a intermediate chamber, and the downstream check valve further defining a downstream chamber, and further including a pressure relief valve having a first sensing line interconnected to the upstream chamber, and having a second sensing line interconnected to the intermediate chamber, said apparatus comprising:

• a. a water flow detector, producing an output signal when a predetermined rate of flow through the water line is detected;
• b. a normally open solenoid valve, located within said first sensing line and interconnected to said water flow detector, said solenoid valve closing in response to said output signal and hydraulically isolating the pressure relief valve from the upstream chamber.

An apparatus for disabling the pressure relief valve of a water line backflow preventer, 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 a intermediate chamber, and the downstream check valve further defining a downstream chamber, the pressure relief valve having a first sensing line interconnected to the upstream chamber, and having a second sensing line interconnected to the intermediate chamber, said apparatus comprising:

• a. means for sampling the water line and producing an output signal when a predetermined rate of flow therethrough is detected;
• b. means for closing off the first sensing line in response to said output signal, thereby hydraulically isolating the pressure relief valve from the upstream chamber.

In a fire line including a backflow preventer, the preventer including a housing having an upstream check valve and a downstream check valve trasnversely 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.

A method for disabling the pressure relief valve of a water line backflow preventer, 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, the pressure relief valve having a first sensor line interconnected to the upstream chamber, and having a second sensor line interconnected to the intermediate chamber, said method comprising the steps of:

• a. sampling the water line and producing an output signal when a predetermined rate of flow therethrough is detected;
• b. closing off the first sensor line in response to said output signal, thereby hydraulically isolating the pressure relief valve from the upstream chamber.