Three general operating practices used to minimize water hammer during CCW pump start up and normal shutdowns
WATER HAMMER The very large CCW flow rate results in huge kinetic energy of the flowing water, and hence it promotes severe water hammer during CCW pump start up, shutdowns and trips. How to Minimize Water Hammer To minimize water hammer the following general operating practices are used during CCW pump start up and shutdown. 1. A sufficient time delay before the next pump Is started up or shut down. This allows the energy of pressure waves in the system to destroy before the system is subjected to another flow surge. Time delay : About 5 minute 2.Proper position and slow opening / closing of the CCW pump discharge valve during pump start up and shutdown a) Each CCW pump is started against its discharge valve fully closed or slightly pre-opened (depending on the plant) and then the valve opens gradually. b) During normal pump shutdown first the discharge valve closes gradually and when it is fully closed (or nearly fully cl...