Backflow Prevention Practice Exam

A pressure vacuum breaker is designed to prevent backflow in a plumbing system by allowing air to enter the system when a drop in pressure occurs, thus protecting against siphonage. The air-inlet valve is a crucial component that should function properly to maintain the breaker's effectiveness.

When the air-inlet valve is damaged, it can lead to a situation where the breaker is unable to release air as necessary. This failure compromises the breaker's ability to equalize pressure and create a vacuum, making it ineffective in preventing backflow. Thus, if the air-inlet valve does not operate correctly, it directly affects the pressure vacuum breaker’s function and could allow unsafe conditions that lead to contamination.

In contrast, while breaks in the supply line and closed valves can also inhibit proper functioning of the system, they do not directly impact the pressure vacuum breaker itself. Elevated discharge piping might influence the hydraulic conditions within the system but is not related to the operational integrity of the air-inlet valve. It is the condition of the air-inlet valve that critically determines the functionality of a pressure vacuum breaker.