Some considerations on water-hammer and cavitation following the sudden closure of a check-valve

The function of a no-return check-valve is to obturate a pipe when the current in it has a tendancy to revert : in normal operation the valve is maintained in open position by the flow and it closes, in case of flow-rate inversion, under the action of its own weight and of the hydrodynamic forces. At the precise time of closure, the stream most of the time is suddenly interrupted, which determines a waterhammer and the separation of a water column followed by other waterhammers.