PRESSURE VACUUM VENT - 3” ALUMINUM Pressure vacuum vent designed for installation on top of the vent pipe of an aboveground storage tank. Poppets seal vapors in the tank when pressure is equalized. The vent allows the tank to breathe during filling and dispensing operations. This vent must be used in conjunction with an emergency vent. It is recommended that the opening pressure setting is set below that of the emergency vent so the normal vent operates first. Settings are approximate.