Shock in the pressure fluid due to the release of kinetic energy if the flow rate suddenly stops (e.g. due to closing a valve or a piston moving against a stop). The pressure wave produced in this manner is reflected at the next pipe elbow and comes back.
The largest possible surge is produced if the closing time t s is less than the propagation time t L of the wave (Joukowski surge):
This pressure surge increases correspondingly if the kinetic energy of the weight must also be retarded as well as the column of fluid.