Which side of the FDC must be connected first and why?

The correct answer is based on the function of the clapper valve in the fire department connection (FDC) system. When connecting hoses to the FDC, it is essential to connect to the side that allows for proper operation of the clapper valve. The clapper valve is designed to prevent backflow from the riser to the FDC, ensuring that water flows only in the desired direction—toward the fire pump and not back into the city water supply.

By connecting to the left side first, the flow of water into the system is optimized, as it aligns with the design of the clapper valve, facilitating efficient water delivery during operations. This procedure reduces the risk of complications such as backflow or improper water supply to the firefighting effort. Prioritizing the left side connection ensures operability and safety for the crew on the scene.

Understanding the role of the clapper valve is crucial for maintaining water supply integrity, ultimately supporting the overall effectiveness of firefighting operations.