Which backflow prevention method uses two independent check valves with an automatic differential valve between them?

Which backflow prevention method uses two independent check valves with an automatic differential valve between them?

• A. Air Gap
• B. Reduced Pressure Principal Device
• C. Atmospheric Vacuum Breaker
• D. Backflow

Answer: (B)

This item is testing your understanding of the reduced pressure principle backflow preventer. This device uses two independent check valves in series with an automatic differential relief valve placed between them. The two checks provide redundancy, while the relief valve maintains a defined pressure differential between the upstream and downstream sides. If either check valve leaks or if downstream pressure rises, the differential valve opens and vents to the atmosphere or a drain, preventing backflow into the supply line. This arrangement offers strong protection in high-hazard situations, such as when pesticides could contaminate drinking water. Air gaps are simple physical separations with no valves, so they don’t match the description. An atmospheric vacuum breaker relies on an air inlet to break the connection when pressure drops but doesn’t involve two independent checks with a differential valve. The term backflow is too general to identify a specific device.

This item is testing your understanding of the reduced pressure principle backflow preventer. This device uses two independent check valves in series with an automatic differential relief valve placed between them. The two checks provide redundancy, while the relief valve maintains a defined pressure differential between the upstream and downstream sides. If either check valve leaks or if downstream pressure rises, the differential valve opens and vents to the atmosphere or a drain, preventing backflow into the supply line. This arrangement offers strong protection in high-hazard situations, such as when pesticides could contaminate drinking water.

Air gaps are simple physical separations with no valves, so they don’t match the description. An atmospheric vacuum breaker relies on an air inlet to break the connection when pressure drops but doesn’t involve two independent checks with a differential valve. The term backflow is too general to identify a specific device.