Tham khảo tài liệu 'know and understand centrifugal pumps episode 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Know and Understand Centrifugal Pumps When a seal is installed into a pump and the motor started an imaginary line is drawn and the seal begins a journey toward the day when the seal will come out of service either from premature failure or from obtaining its maximum service life. On one side of the imaginary line are the events in the manufacture of the seal its handling storage and installation. On the other side of the imaginary line are the events that occurred after the pump and seal were started the first time. AUTHOR S NOTE Maybe you ve heard your auto mechanic say on installing a new radiator water pump or alternator onto your car . that if it runs for 5 minutes then it will run for 15 years. If it s going to fail it will do so within the first five minutes. Mechanical seal problems originating in the factory storage handling and installation will be evident within the first few moments or hours of operation. Consider fractured faces from poor handling or a missing o-ring from poor assembly or installing a 50 mm seal onto a 48 mm shaft poor installation . These failures and the leaks will be immediately evident. If there is a chemical incompatibility between the liquid and an o-ring rubber compound or if heat is generated from too much spring tension this will be evident within a few hours or days. Galvanic corrosion or inadequate spring tension will reveal itself in a few weeks. Certainly at the moment of starting a pump with a new seal installed the events prior to the installation begin to disappear as a cause or origin of failure and the factors of operation process and design in the system begin to appear as possible reasons for any premature failure. Let s begin the analysis or autopsy with the physical evidence on the component seal parts. O-ring The elastomer failure About half of all pumps in the shop today were pulled out of service because they were leaking or wouldn t hold pressure or pump. This is most likely a leaking o-ring. The o-ring is the
