What is a water hammer?
Water hammer is a term used to describe a hydraulic shock to an element that happens when the high pressure pump is started before all air has been flushed from the system. This could be the case at initial startup or at operational startups when the system has been allowed to drain. It can cause longitudinal and circumferential cracks on fiberglassed elements. It can also result in membrane compaction which is typically associated with low permeate flow and improved salt rejection. It can also cause o-rings to leak due to mechanical stress caused by element movement. To prevent this from recurring, the elements in the pressure vessel should be shimmed. Shimming the elements at the time they are initially loaded will minimize the shifting that occurs during startups and shutdowns.
