a type of pressure change which occurs when the speed of the change of condition in the liquid is considerable compared with the reflection time of the wave,so that the compressibility of the liquid and the elasticity of the pipe-line may no longer be neglected, a sharp hammer-like blow from a steep-fronted pressure wave in water cused by the sudden stoppage of flow in a long pipe when a valve is closed sufficiently rapidly, torustikus liikva vedeliku õhu järsk suurenemine voolukiiruse kiire muutumise korral