Civacon's MaxAir II Emergency Valve improves safety in petroleum-handling and various other fuel-transport applications. Designed for use in fuel-handling applications on tank trailers transporting products such as gasoline, diesel, biodiesel, ethanol and other typical petroleum products carried in aluminum DOT 406-style tankers. Features an externally ported air cylinder exhaust port, which uses three independent seals to completely isolate the air cylinder. The valves are outfitted with Viton GFLT wetted seals and a standard Teflon-encapsulated seat, which make them compatible with a wide array of products. Has a shearable air inlet fitting allows the valve to close, even if open, during an under-ride accident.