Failure of mechanical seals in centrifugal pumps

This fourth paper in the troubleshooting series deals with mechanical seals. Often a seal failure is diagnosed through visual inspection of the failed seal's components; this may yield the condition that existed in the seal cavity prior to, or at the time of, failure. The events that led to this condition are usually linked to the real cause of failure, which often requires us to move beyond the vicinity of the seal itself in our search for cause of failure. The extensive nature of this topic does not allow full coverage of all aspects of diagnosis, but this first of three discussions by Stan Shiels will deal with the prime areas associated with seal failure. His next article will address some specific in more detail.