Backflow Prevention Practice Exam

Which condition would cause a pressure vacuum breaker to discharge water?

1. Supply pressure loss without a functional check valve

2. Fully opened valves

3. Blocked irrigation sprinkler heads

4. Closed discharge piping

The correct answer is: Supply pressure loss without a functional check valve

When assessing the functioning of a pressure vacuum breaker, it's essential to understand its role in backflow prevention. A pressure vacuum breaker operates by maintaining a specific pressure in the system to prevent backflow due to suction. If there is a supply pressure loss and no functional check valve is present, the pressure vacuum breaker will not be able to maintain the necessary pressure in the line. As a result, water will discharge from the device to relieve the negative pressure created by the loss. This is a vital mechanism that protects the potable water supply from contamination. In contrast, fully opened valves do not create conditions conducive to the discharge of water from the vacuum breaker because the system still experiences normal operational conditions. Blocked irrigation sprinkler heads may restrict water flow but do not directly influence the vacuum breaker's function. Likewise, closed discharge piping would impede water flow and pressure but would not lead to the discharge of water from the vacuum breaker itself since it would not be experiencing the negative pressure that triggers the discharge.