At this time, the valve V1 is closed and V2 is open. As the water flows, valve V2 gradually closes interrupting the flow of water. The momentum of the water is converted into pressure energy which opens the valve V1 and pushes the water through the outlet. The outlet is of a small cross section as compared to the inlet.
As the water is discharged, the pressure energy reduces and the valve V1 closes and V2 opens and the cycle starts over again. Thus, only a small quantity of water is discharged. The cylinder C1 serves as a pulsation damper which absorbs the fluctuations during each cycle.