The Fainger make Pressure / Vacuum Relief Valve with Flame Arrester is designed to prevent costly evaporation losses, tank rupture due to over-pressure, and collapse due to vacuum. The flame arrester protects tank against fire and explosion caused by exterior sources of ignition. Pallets in the vent housing minimize air and vapor loss as the tank “breathes”. They open and close just enough to maintain safe working pressures and avoid damage to the tank. The flame arrester element is mounted externally and is only exposed to vapors when venting.