Before which point must the air inlet of a pressure vacuum breaker open according to pressure gauges?

The air inlet of a pressure vacuum breaker must open at 1.0 psi. This is a crucial aspect of the operation of a pressure vacuum breaker, as it is designed to prevent the backflow of contaminated water into the potable water supply. The air inlet serves to break the vacuum when there is a drop in pressure, thus allowing air to enter the system and equalize pressure.

When pressure drops to 1.0 psi, the air inlet opens to ensure that there is sufficient air to prevent a vacuum condition that could lead to back siphonage. This mechanism is vital for maintaining the safety and integrity of the water supply as it helps avoid the risk of water being drawn back into the system from potentially contaminated sources.

Understanding this pressure threshold is essential for those involved in the installation, maintenance, and testing of backflow prevention devices, as it directly impacts the device's effectiveness in providing protection against backflow.