Axial check valve behaviour during flow reversal

An ideal check valve is supposed to have a zero pressure loss when the flow rate direction is positive and a negative flow rate is not possible. A real check valve has a low pressure loss and it is possible to suppress negative flow (especially when the check valve is new) under steady conditions. The transition between the steady positive flow and zero flow is often connected with a water hammer, here called check valve slam. An experimental investigation of behaviour of the axial check valve disc during the flow reversal is described in this paper. A high-speed camera was used for the disc position observation and pictures are compared with pressure pulsations and the flow rate.