Backflow preventers for beverage dispensing equipment are engineered for installation in carbonated post-mix dispensing systems. ASSE 1022 covers a backflow prevention device designed to protect the potable water supply serving beverage dispensing equipment. These devices are intended for use under continuous or intermittent pressure conditions. These devices shall consist of two independently acting check valves biased to a normally closed position. An atmospheric port shall be located between the check valves and shall be biased to a normally open position. The port shall vent liquids, gases, or both, under backflow conditions.