Backflow Prevention Practice Exam

A pressure vacuum breaker is designed primarily to ____?

1. Prevent backpressure

2. Prevent backsiphonage

3. Control fluid temperature

4. Reduce system pressure

The correct answer is: Prevent backsiphonage

A pressure vacuum breaker is specifically engineered to prevent backsiphonage. Backsiphonage occurs when there is a drop in pressure in the water supply system, causing contaminated water to be siphoned back into the potable water supply. The pressure vacuum breaker is equipped with a check valve that opens when the system pressure drops, allowing air to enter the system and thereby breaking the siphon effect. This mechanism effectively stops contaminated water from flowing back into the clean water supply, ensuring the safety of the drinking water. This design is crucial in areas where there is a potential for the cross-connection of non-potable and potable water sources, as it protects the water quality and public health.