Patent ID: 8668105

Claim:
A floating plug emergency drain valve for a floating roof used with a storage tank for volatile fluid, where said floating roof includes vertically spaced apart top and bottom surfaces and a duct having open top and bottom ends that extends through said roof for drainage through said roof of water accumulated atop said roof, said valve having an open state for allowing said accumulated water to drain downward through said duct and a closed state for blocking vapors from rising upward through said duct, said valve comprising: a. a valve seat mountable in said duct below said top surface of said roof, said valve seat having a generally truncated conical upper sealing surface, b. a valve sealing element having (i) a buoyant ball-like upper part, (ii) a bottom part formed as a plug extending downward with a generally truncated conical outer sealing surface conforming generally to and sealing with said valve seat upper sealing surface when said valve is in its closed state, and (iii) a guide pole extending upward from said upper part, and c. a guide member mountable to said roof to slidably receive said guide pole and to thereby guide said plug to align and seal with said valve seat when said valve is in said closed state.