The differential pressure relief valve on a Reduced Pressure Zone (RPZ) assembly must open before the differential pressure across the inlet drops below what value?

The correct value for the differential pressure relief valve on a Reduced Pressure Zone (RPZ) assembly to open is indeed 2.0 psi. The function of the differential pressure relief valve is critical in maintaining the safety and functionality of the RPZ assembly. Its primary role is to ensure that the downstream pressure remains lower than the supply pressure, thereby preventing any potential backflow that could contaminate the potable water supply.

When the differential pressure drops below 2.0 psi, it indicates that the system is approaching conditions where backflow might occur. By opening at this threshold, the relief valve helps to maintain the intended operation of the RPZ assembly, ensuring that the system continues to function effectively in preventing backflow. This is important for safeguarding public health and maintaining water quality.

Understanding this specific pressure threshold is vital for professionals working with backflow prevention devices, as it ensures they can effectively monitor and maintain these systems in accordance with standards and regulations.