Water Hammer – Definition, Factors Affecting Water Hammering

Water Hammering


If water is flowing through a channel and it is stopped abruptly i.e its momentum is broken so a pressure surge or wave results, this effect produced is called water hammer or hammer blow. This effect can be produced in any fluid. When a flow is stopped backwater effect is produced in which a wave of water moves against the flowing water.


Water hammer is caused by a pressure or shock wave that travels through the pipes, generated by a sudden stop in the velocity of the water, or a change in the direction of flow. If the pipe is suddenly closed at the outlet, the mass of water before the closure is still moving forward with some velocity, building up a high pressure and shock waves.

Water hammer Phenomenon can cause failure of fittings or burst pipes

Factors contributing to water hammer


  1. Improperly sized piping in relation to water flow velocity
  2. High water pressure with no pressure-reducing valve
  3. Straight runs that are too long without bends;
  4. Poor strapping of piping system to structure
  5. No dampening system in place to reduce or absorb shock waves


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