The Principle Operation of a Backflow Prevention Device for Beverage Dispensing Equipment – Backflow Prevention Backsiphonage Condition

If a backsiphonage condition were to occur, the BPBDE first check valve will seal against the diaphragm closing the first check valve and opening the atmospheric vent. The second check would close tight against the seat. Since the atmospheric vent is open, a small amount of water will discharge from the open vent. Once the water discharges, the atmospheric vent is now allowing air to enter the BPBDE atmospheric vent breaking the vacuum and eliminating the siphon. The BPBDE is providing protection and not allowing non-potable water from entering the potable water system.

The Principle Operation of a Backflow Prevention Device for Beverage Dispensing Equipment – Backflow Prevention Backsiphonage Condition – Check Valve Failure

If a backsiphonage condition were to occur, the first check valve will seal against the diaphragm closing the first check valve and opening the atmospheric vent. If the first check valve was fouled open or did not close tight, the BPBDE second check would close tight against the seat preventing carbonated water or carbon dioxide gas from entering the potable water system. Since there is a backsiphonage condition and no inlet pressure, the atmospheric vent is open. Supply pressure closes the atmospheric vent. Since the atmospheric vent is open, air is entering the BPBDE atmospheric vent breaking the vacuum and eliminating the siphon. The BPBDE is providing protection and not allowing non-potable water from entering the potable water system.