The performance of 3 stage air valve has been investigated experimentally. Throughout this work, more understanding of the dynamic behavior of air valves during transient is achieved. A wide range of tests were conducted, the aim of which were to obtain a graphical representation of the differential pressure versus water discharge rate characteristics for different valve float configurations and to determine the exact point at which dynamic closure occurs, whenever it occurs, and to determine the peak pressure induced when a flow of water column reaches and closes the valve.
The test rig for water discharge tests was constructed from a transparent pipe, and also transparent valve was used to allow visual interpretation of the valve behavior during transients using high speed camera. The rig was interfaced with a high pressure air/water supply in order to obtain the necessary pressure difference to vary the water column velocity. The pressure was monitored and recorded at different locations along the pipe and at the valve. Water column velocity was also recorded via an ultrasonic clamp on flow meter. The outputs of the various sensors were monitored by means of a data acquisition device.