How should a hydrant be opened to prevent a water surge (hammer), if possible?

When opening a hydrant, it is essential to do so slowly to prevent a water surge, often referred to as water hammer. Water hammer occurs when a sudden change in water flow creates a pressure wave that can damage pipes and fittings. By opening the hydrant slowly, the water pressure can build gradually, allowing the system to adjust and minimizing the risk of a sudden forceful surge.

Opening the hydrant too quickly can create a rapid change in water velocity, leading to those damaging surges in pressure. Conversely, taking the time to open it slowly allows for a smoother transition of flow, ensuring that both the hydrant and the connected hoses, including those attached to fire engines or other equipment, are protected from potential damage caused by sudden pressure changes. This method is a critical practice in firefighting procedures to maintain the integrity of water supply lines and equipment.