AWWA ACE95138

Hydraulic transients occur when there are sudden changes in flow and usually take place in a matter of seconds. They typically arise from equipment failure or operational errors such as the sudden starting and stopping of pumps or the rapid opening and closing of valves. The most severe transients often result from the stoppage of one or more pumps (pump trip). This causes the pump discharge pressure to drop rapidly and can lead to pressures below atmospheric and even to the vapor pressure of the liquid. If vapor pressure is reached, cavity formation can occur immediately downstream of the pumps and at intermediate high points in the pipeline. When the vapor cavity collapses, the resulting returning pressure wave may cause a sharp rise in the pressure that may exceed pipe design capacity. This is a serious problem and must be carefully examined. Due to the importance of its largest transmission mains, the Detroit Water and Sewerage Department (DWSD) is currently involved in a project to identify facility improvements that would control transient pressures within prescribed limits.

Product Details

Published:

01/01/1995

ISBN(s):

0898678358

Number of Pages:

20

File Size:

1 file , 680 KB