A vent installed on an aboveground tank to provide for vapor release in event of excessive pressure build-up resulting from fire exposure of the tank. Such vents are designed to operate at higher pressure settings and to allow a greater flow rate of vapors than those which actuate the operation of pressure/vacuum vents on normal vent pipes.

Aboveground storage tanks have two separate openings for vents–one for emergency venting and one for normal venting.