Backflow Prevention Practice Exam

Which component is essential to prevent backflow in a plumbing system?

1. Check valve

2. Expansion tank

3. Temperature relief valve

4. Shut-off valve

The correct answer is: Check valve

The check valve serves a critical role in preventing backflow within a plumbing system. It is designed to allow fluid to flow in only one direction, effectively blocking reverse flow that could contaminate the potable water supply. By automatically closing when fluid attempts to flow back, the check valve helps maintain the integrity and safety of the system, ensuring that water does not revert to an area where it could introduce pollutants. The other components mentioned serve different functions. An expansion tank is used to accommodate changes in water volume due to temperature fluctuations, helping to maintain pressure and prevent excessive buildup. A temperature relief valve is crucial for safety in water heating systems, releasing water if the temperature exceeds safe levels, but does not prevent backflow. A shut-off valve controls the flow of water in a system, allowing maintenance and repairs to be conducted safely, but it does not inherently prevent backflow on its own. Thus, the check valve is the key component specifically focused on backflow prevention in plumbing systems.