Warning system for preventing overfill in underground tanks having a gage box

Claim 1

A warning system for preventing overfill of liquid in an underground tank provided with a gage box having connecting means at ground level, comprising: a hollow housing designed to hold an electrical battery and having a bottom opening and bottom connecting means connectable in leakproof relationship with the gage box connecting means, a length of pipe extending from about ground level through said gage box and into the top portion of said tank and having top and bottom connecting means, and being connected at its top to the bottom oPening of said housing, and serving as a conduit for electrical wiring, a retainer connected at its top to the bottom of said pipe and having an open hollow bottom with a passage into said pipe, a float switch disposed within the hollow bottom of said retainer, and having movement-limiting means for restricting movement of the float to within said retainer, and serving to make electrical contact when the liquid level in said tank rises to a predetermined height, a cover, disposed over and attached to said housing, a signal assembly disposed on and attached to said cover, and wiring means leading from said switch, through said pipe and said housing and connectable to said battery and said signalling means for actuation of the latter when said float switch becomes closed by rise of fluid level in said tank.