What distinguishes a reduced pressure principle back-flow assembly from a double check back-flow assembly?

A reduced pressure principle back-flow assembly is distinguished by the presence of a relief valve, which is a critical component that ensures the protection of the potable water supply from contaminants or harmful substances. This relief valve allows for the discharge of water if the pressure in the system drops below a certain threshold, thus preventing back-flow. This design is essential in situations where there is a risk of back-flow contaminating the drinking water, making it particularly suitable for high-hazard applications.

In contrast, a double check back-flow assembly does not contain a relief valve. Instead, it relies on two check valves to prevent back-flow, which offer adequate protection in lower hazard situations but do not provide the same level of assurance as the reduced pressure principle assembly. The lack of a relief valve means that double check assemblies are not always suitable for environments where contamination risks are higher, as they do not actively release water to alleviate back-pressure situations.

Understanding this key difference helps in selecting the appropriate back-flow assembly for specific applications, thereby ensuring the safety and integrity of water supplies in various settings.