Backflow Prevention Practice Exam

Which of the following conditions can lead to a check valve failure?

1. Disc pitting

2. Air-inlet valve leakage

3. Chatter or noise during flow

4. Water hammer

The correct answer is: Disc pitting

Disc pitting is a significant condition that can lead to check valve failure. Pitting refers to the formation of small holes or cavities on the surface of the valve disc, usually caused by corrosion or erosion. When the disc becomes pitted, it can fail to create a proper seal when the valve closes, allowing backflow to occur. This failure can compromise the integrity of the system and lead to unwanted contamination or other operational issues. While other conditions like air-inlet valve leakage, chatter or noise during flow, and water hammer can also indicate problems with a system or valve, they do not specifically lead to check valve failure in the same direct manner as disc pitting. Air-inlet valve leakage can contribute to pressure fluctuations but does not inherently damage the check valve itself. Chatter or noise can indicate issues with flow dynamics or improper sizing but does not necessarily result in physical damage to the valve. Water hammer, a shock wave caused by sudden changes in flow, can cause stress on pipes and valves, but check valves can often withstand these surges if they are properly designed. Thus, the presence of disc pitting represents a direct threat to the physical functionality and sealing capability of a check valve, making it the best answer in this context.