Which assembly is designed to be installed for back-flow prevention and has a pressure relief feature?

The reduced pressure principle assembly is specifically designed for back-flow prevention and includes a pressure relief feature. This assembly works by utilizing two independent check valves and a pressure differential relief valve positioned between them. In normal operating conditions, the system maintains a pressure that keeps water flowing in one direction, preventing contamination from entering the potable water supply.

If there is a drop in pressure or an occurrence of backflow, the pressure relief valve opens to discharge water, ensuring that any contaminants are expelled and do not enter the clean water system. This feature makes the reduced pressure principle assembly suitable for high-risk applications where the potential for backflow is significant.

In contrast, other assemblies such as the double check assembly do not provide a pressure relief feature. An air gap assembly is more about creating a physical separation to prevent siphoning rather than utilizing a mechanical pressure relief system, while an atmospheric vacuum breaker is designed to prevent back siphonage but does not incorporate a pressure relief valve that functions under backflow conditions. These differences highlight the unique role of the reduced pressure principle assembly in safeguarding water supply systems.