Patent ID: 7721903

Claim:
An automatic drain assembly for a floating roof covering a liquid product stored in a tank, said roof including a deck with top and bottom surfaces, said drain pipe having an open top end and an opposite open bottom end, the drain assembly comprising: (a) a drain pipe extending from a predetermined elevation at a maximum allowable level for accumulated water above said top surface of said floating roof, downward through said roof, providing a conduit for water to be drained from said deck, said drain pipe having an open top end and an opposite open bottom end, (b) a drain pipe sealing cover lying by its weight in its closed position atop said open top end of said drain pipe, said cover having opposite top and underside surfaces, and (c) at least two buoyant members secured in spaced apart relation to the underside of the cover forming a collar that at least partially surrounds said top end of said drain pipe. for imparting a buoyant force from water accumulated on said deck to lift said cover from said closed position where it lies and is sealed against said top end of said drain pipe to an open position where it is spaced above said open top end of said drain pipe, to thereby allow water to flow into the drain pipe, said cover adapted to be repeatedly moved between its closed and open positions as required to drain water from said deck.