The Principle Operation of a Backflow Prevention Device for Beverage Dispensing Equipment – Backflow Prevention Backpressure Condition
If a backpressure condition were to occur, the BPBDE second check would close tight against the seat, if not fouled open. The first check valve will seal against the diaphragm closing the first check valve and opening the atmospheric vent. 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. 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 Backpressure Condition – Check Valve Failure
If a backpressure condition were to occur, the BPBDE second check would close tight against the seat. If the second check valve was fouled open or did not close tight, the first check valve will seal against the diaphragm closing the first check valve and opening the atmospheric vent. Since the atmospheric vent is open, carbonated water or carbon dioxide gas will discharge from the open vent. The amount of carbonated water or carbon dioxide gas that will discharge is dependent on the volume in the downstream piping. The BPBDE is providing protection and not allowing non-potable water from entering the potable water system 