If backsiphonage occurs with a reduced-pressure device and pressure drops below 2 psi, what will happen?

When backsiphonage occurs in a system with a reduced-pressure principle backflow prevention assembly, the primary concern is maintaining proper hydraulic conditions to prevent contaminants from entering the potable water supply. If the pressure in the system drops below 2 psi, the relief valve of the device is specifically designed to respond appropriately to such a low-pressure situation.

In this scenario, the relief valve will remain fully open, which creates a pathway for air to enter the system. This action is crucial because it helps to ensure that negative pressure does not draw potentially contaminated water back into the clean water supply. The formation of an air gap is a key feature of this configuration, as it provides an additional layer of safety, preventing any backflow that could occur in adverse pressure conditions.

Keeping the relief valve open and allowing for an air gap ensures that there is no vacuum created within the system, which could lead to backsiphonage and the associated health risks. This design is essential in maintaining the integrity of the water distribution system and preventing contamination from occurring during instances of pressure loss.