What does the critical level on a vacuum breaker indicate?

The critical level on a vacuum breaker refers to the minimum elevation at which the device must be installed to function properly and prevent backflow. This elevation is critical for ensuring that the air inlet of the vacuum breaker remains above the flood level of the fixture it serves, which is essential for preventing contamination of the potable water supply due to back siphonage.

Understanding the importance of this installation height is paramount, as it ensures that the vacuum breaker can effectively protect the system from negative pressures that might draw contaminated water back into the clean supply. Properly adhering to the minimum elevation specified for the device safeguards public health by maintaining the integrity of drinking water systems.