Why do firefighters open and close all valves and nozzles slowly?

Firefighters open and close all valves and nozzles slowly primarily to avoid water hammer. Water hammer occurs when there is a sudden change in the flow of water, causing a shock wave that creates a loud banging noise and can result in damage to pipes, valves, and fittings. By gradually adjusting the valves and nozzles, firefighters ensure a smoother transition of pressure and flow, minimizing the risk of such violent pressure changes.

This careful operation helps protect the entire water delivery system during firefighting efforts, especially when dealing with high-pressure hoses and heavy water flow. Practicing this technique is crucial for preserving the integrity of firefighting equipment and ensuring safety for both the firefighters and the infrastructure they are working with.