Water hammer can cause pipelines to break or induced damage to equipment if the water hammer is severe enough.
Oscillating pressure waves generated in a water pipe following an abrupt alteration of the flow. The pressure surge oscillates back and forth in the pipe system until dampened by the system. It occurs in a closed piping system as a result of the pressure being rapidly increased when the liquid velocity is suddenly increased. This damaging effect is usually the result of sudden starting, stopping, change in pump speed, or the sudden opening or closing of a valve.
The severity of the phenomenon is dependent on a number of variables, such as change of velocity during the reflection cycle, pipe material characteristics (e.g. stiffness) as well as liquid characteristics. Water hammer can cause pipelines to break or induce damage to equipment if the water hammer is severe enough. However moderate water hammer can be positive if it is kept to a level where it does not damage the piping as the “blow” can release settled matter in the pipeline.
Water hammer can be controlled by regulating valve closure times, by including stand pipes (open at the top), surge chambers or relief valves into the system. These arrangements will act as dampers by providing a cushion to absorb the force of moving water in order to prevent damage to the system.