초록 ▼

A back flow preventing device is disclosed which prevents the reverse flow of water from a point of use into a water supply system. The device has a casing with coaxially aligned inlet and outlet openings, and containing coaxially aligned inlet and outlet check valves. The coaxial alignment of the i

A back flow preventing device is disclosed which prevents the reverse flow of water from a point of use into a water supply system. The device has a casing with coaxially aligned inlet and outlet openings, and containing coaxially aligned inlet and outlet check valves. The coaxial alignment of the inlet and outlet openings, and of the inlet and outlet check valves serves to minimize the pressure drop through the device. Between the inlet and outlet check valves is a diaphragm actuated relief valve which opens to drain the passage between the check valves if they should malfunction or if there is a drop in the supply line pressure sufficient to cause actual or potential reverse flow back toward the supply line. The internally-located inlet and outlet check valves are each removably secured in place by internally-located retaining rings.

대표청구항 ▼

A device for preventing the back flow of water from a point of use into a water supply line comprising: (a) a unitary casing having a water inlet opening, a water outlet opening and a drain vent opening, said water inlet and water outlet openings being coaxially aligned, the interior of said casing

A device for preventing the back flow of water from a point of use into a water supply line comprising: (a) a unitary casing having a water inlet opening, a water outlet opening and a drain vent opening, said water inlet and water outlet openings being coaxially aligned, the interior of said casing defining an inlet chamber, a central chamber and an outlet chamber, said chambers being coaxially aligned with each other and with said water inlet and water outlet openings to form a straight through flow path for the water, said interior of said casing also defining a drain vent chamber communicating with said drain vent opening and said central chamber, and said drain vent chamber being offset from said coaxially aligned inlet, central and outlet chambers; (b) a first check valve assembly removably attached to the interior of said casing between said inlet and central chambers, said first check valve being biased in a closed position to prevent the flow of water therethrough and opening to permit the flow of water therethrough when the water pressure in the water inlet chamber exceeds a predetermined level; (c) a first removable retaining means for retaining said first check valve assembly in said attached position, said first removable retaining means being located in said central chamber; (d) a second check valve assembly removably attached to the interior of said casing between said central and outlet chambers, said second check valve being biased in a closed position to prevent flow of water therethrough and opening to permit the flow of water therethrough when the water pressure in said central chamber exceeds a predetermined level; (e) a second removable retaining means for retaining said second check valve assembly in said attached position, said second removable retaining means being located in said central chamber; (f) a relief valve located within said casing interposed between said central chamber and said drain vent chamber, said relief valve being offset from said coaxially aligned inlet, central and outlet chambers, and said relief valve being biased in an open position; (g) a flexible diaphragm attached to said casing and to said relief valve, one side of said diaphragm communicating with said central chamber and the other side of said diaphragm communicating with said inlet chamber, such that the normal pressure differential between said inlet and central chamber causes said relief valve to close thereby preventing water flowing from said central chamber to said drain vent chamber; and (h) a cover removably attached to said casing over an opening therein such that upon removal of said cover, said first and second check valve assemblies being removable from said casing interior without removal of said flexible diaphragm.