What are the common causes of water hammer in a piping system?

Water hammer, also known as hydraulic shock, is a pressure surge or wave that occurs in a piping system when a fluid in motion is suddenly forced to stop or change direction. Several factors can cause water hammer. The most common cause is the rapid closure of a valve. When a valve is suddenly closed, the momentum of the water flowing through the pipe is abruptly stopped, creating a pressure wave that travels back and forth through the pipe. This pressure wave can be several times higher than the normal operating pressure of the system. Another cause is the sudden starting or stopping of a pump. When a pump is started or stopped quickly, it can create a pressure surge in the piping system. Air in the piping system can also contribute to water hammer. Air pockets can compress and expand rapidly, creating pressure waves when the flow changes. Improperly sized or installed piping can also increase the risk of water hammer. Long, straight runs of pipe are more susceptible to water hammer than shorter, more complex piping systems. Additionally, systems with high flow velocities are more prone to water hammer. For example, in a long pipeline, a sudden valve closure can create a pressure wave that can damage the pipes, valves, and fittings. Water hammer can be mitigated by using slow-closing valves, installing air chambers or surge tanks, and properly sizing the piping system.