What is the difference between a reduced pressure principle backflow device and a double check backflow device? The RP has a __________.

What is the difference between a reduced pressure principle backflow device and a double check backflow device? The RP has a __________.

• A. Diaphragm
• B. Relief Valve
• C. Check Valve
• D. Vent

Answer: (B)

The difference comes from the presence of a relief valve. A reduced pressure principle backflow device contains a relief valve placed between two check valves. If backflow or a drop in pressure occurs, this relief valve opens and vents water to drain, maintaining a reduced-pressure zone and preventing contaminants from being drawn back into the supply. A double check device uses two check valves to block reverse flow but does not include a relief valve to vent the zone, so it provides protection without the additional discharge path.

The difference comes from the presence of a relief valve. A reduced pressure principle backflow device contains a relief valve placed between two check valves. If backflow or a drop in pressure occurs, this relief valve opens and vents water to drain, maintaining a reduced-pressure zone and preventing contaminants from being drawn back into the supply. A double check device uses two check valves to block reverse flow but does not include a relief valve to vent the zone, so it provides protection without the additional discharge path.