Abstract: A floating plug emergency drain valve for a floating roof used with a storage tank for volatile fluid, where the floating roof includes vertically spaced apart top and bottom surfaces and a duct having open top and bottom ends that extends through the roof for drainage through the roof of water accumulated atop the roof, the valve having an open state for allowing the accumulated water to drain downward through the duct and a closed state for blocking vapors from rising upward through the duct, the valve including a valve seat having an upper sealing surface, and a valve sealing element having a buoyant ball-like upper part, and a bottom part formed as a plug extending downward with a bottom sealing surface sealing with the valve seat upper sealing surface when the valve is in its closed state.

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