Waterhammer Caused by Valve Stroking in a Pipe Line with Two Valves

Abstract

This paper deals with the waterhammer caused by closing the valves in a pipe line with two valves, one at the outlet end (discharge valve), another at the center of the pipe line (mid valve). Theoretical and experimental results indicate that the maximum head rise in the pipe line with two valves is lower than that produced by closing the discharge valve only, when the speed of closing the valve is the same. Moreover it is shown that when the mid valve is nearer to the reservoir or the mid valve is closed some time before the discharge valve, the head drop at the point just after the mid valve increases so much that the possibility of water column separation increases ; and when the mid valve is nearer to the discharge valve, the head rise at the point just before the mid valve increases.