What is the typical pressure drop required in an RPZ device to prevent backflow?

In an Reduced Pressure Zone (RPZ) device, a pressure drop of at least 2 pounds per square inch (psi) is necessary to effectively prevent backflow. This pressure drop is crucial because it creates a difference between the inlet pressure and the pressure in the zone that is intended to remain free from contamination. When the pressure in the protected system is lower than the supply pressure by this specified amount, it ensures that backflow cannot occur, thereby maintaining a safe and non-contaminated water supply.

The design and operation of an RPZ device hinge on maintaining this pressure drop as it allows the device to function properly under varying conditions of flow and pressure. If the pressure drop is insufficient, it could lead to backflow situations where contaminated water could potentially enter the clean water system, posing serious health risks. Thus, adhering to the minimum pressure drop standard is vital for safeguarding public health and maintaining water quality.