Patent ID: 6490738
Filing Date: 2002-12-10
Classification: E03C,Y10T

Abstract:
A plug, comprising:a solid circular plug body having first openings formed therein; and a valve co-operating with the plug body and having second openings formed therein, the valve being moveable relative to the plug body between a first closed position abutting the plug body and a second open position spaced from the plug body; wherein the valve is resiliently biased to the first closed position while hydrostatic pressure on the valve is less than a predetermined value; wherein the first and second openings are so arranged that in the first closed position the first openings are blocked by solid portions of the valve while the second openings are blocked by solid portions of the plug body to prevent water passage therethrough; and wherein in the second open position the first and second openings communicate to form a passageway to allow water to drain therethrough at a rate sufficient to prevent overflow; and wherein a top surface of the valve abuts an underside surface of the plug body when the valve is in the first closed position, at least one of the top surface of the valve and the underside surface of the plug body being formed with a raised circular protrusion to form a seal between the abutting surfaces.