Backflow Prevention Practice Exam

Which system feature can potentially harm the operation of a pressure vacuum breaker?

1. Elevation of the discharge piping

2. Presence of a check valve

3. Excessive backpressure

4. Reduction of atmospheric pressure

The correct answer is: Excessive backpressure

The operation of a pressure vacuum breaker can be adversely affected by excessive backpressure. A pressure vacuum breaker is designed to protect against backflow into the potable water supply, and it functions based on maintaining a specific pressure relationship. When excessive backpressure occurs in a system, it can force water back into the potable water supply line, thereby defeating the purpose of the pressure vacuum breaker. This can lead to contamination of the drinking water system, which is a significant concern for public health and safety. In the context of backflow prevention, it is crucial to maintain the correct pressure for the device to operate correctly. If the pressure exceeds what the pressure vacuum breaker can handle, the device may fail to function as intended, allowing harmful substances to be siphoned back into the water supply. Other factors, while they can contribute to the device's overall function, do not pose the same direct risk as excessive backpressure. The elevation of discharge piping is a normal design consideration, and the introduction of a check valve is sometimes necessary for system operations but does not inherently harm the device's function. Additionally, a reduction in atmospheric pressure can affect the operation but is generally less impactful than excessive backpressure when focusing on the primary harm to the device's operations.