What action can lead to the occurrence of water hammer in a system?

Water hammer is a phenomenon that occurs when there is a sudden change in the flow rate of water within a pipe system, creating shock waves that can result in loud banging noises and potential damage to pipes and fittings. The action that most commonly leads to this occurrence is opening or closing a valve too quickly.

When a valve is closed suddenly, the flow of water is abruptly halted, and the kinetic energy of the moving water has nowhere to go. This causes a pressure surge, creating a shock wave that travels back through the pipe. The force of this pressure surge can lead to significant stresses on the system, potentially resulting in pipe failure or damage to valves and fittings.

On the other hand, reducing flow gradually allows for a smooth transition in water movement, minimizing any drastic changes in pressure. Maintaining constant pressure or using larger pipe sizes generally does not contribute to the occurrence of water hammer, as these actions tend to stabilize flow and pressures within the system. Therefore, the method of quickly manipulating a valve is a direct cause of the sudden pressure changes that characterize water hammer.