Which backflow prevention device features a center relief valve?

The correct answer is the reduced pressure backflow assembly. This device is specifically designed to prevent backflow and consists of two check valves and a center relief valve. The center relief valve plays a crucial role in maintaining the system's integrity by allowing for the pressure to be relieved between the two check valves. If the pressure in the system drops, the relief valve opens to prevent potential contaminants from entering the potable water supply. This feature is essential in situations where backpressure or backsiphonage could lead to contamination, making the reduced pressure backflow assembly a vital component in safeguarding public water systems.

In contrast, other backflow prevention devices like the dual check valve and pressure vacuum breaker do not employ a center relief valve in their design. A dual check valve typically consists of two check valves that work together to prevent backflow but does not include the additional relief function. The pressure vacuum breaker is primarily used to protect against backsiphonage and features an air inlet valve rather than a relief valve. An air gap, on the other hand, is a physical separation between the water supply and potential contamination source, offering a simple yet effective method of prevention without any moving parts or valves.