Discussion on common problems of mechanical seals
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This post was last edited by springpang on 2015-9-24 at 11:21. I have been working in after-sales service for mechanical seals, moving from Xi’an Yonghua to Dongguan Huahui, and I have been in this field for over 6 years now. Everyone is welcome to ask me questions regarding mechanical seals in the context of daily work (including seal installation, identification of leakage causes, etc.). I will do my best to provide answers. Contact method: Private message within the website; I am usually online on weekdays. PS: Please approach the discussions with an attitude of learning from and communicating with one another. No one is perfect; we should learn from one another.* There is a difference in when one learns something, but everyone has their own area of expertise.
The high-pressure centrifugal ammonia pump is equipped with a double-end mechanical seal; the sealing medium is deionized water, and the friction pair consists of high-temperature sintered silicon carbide against graphite. It functions well when in operation, but leakage occurs after just two or three starts and stops (mostly external leakage, although internal leakage is also possible). What causes this?
Should the desalinated water be used as an isolation fluid? Also, is the leakage amount large or small? What flushing method is being used?
Desalinated water is used as the isolation fluid; at first, the leakage amount is small, in the form of drops. After operating for some time, it gradually develops into continuous dripping, eventually turning into a ‘light stream’. The flushing plan is Plan 54
At first, the leakage was minimal, but it gradually increased, which indicates that the sealing surface has been damaged. In most cases, this is caused by the medium entering the sealing surface. Does your pump experience vacuum conditions? Try to avoid starting and stopping the pump intermittently after it has been started; frequent start-stop operations cause significant damage to the mechanical seal. During pump operation, it is necessary to monitor whether the inlet and outlet pressures remain stable; if there are large fluctuations, it indicates a problem with the process
The demineralized water system is equipped with a filter; air is exhausted before the pump starts operating, and there should be no vacuum conditions during operation. However, since the first shutdown after the mechanical seal was installed (about 1 month ago), dripping from the outer side of the seal was observed during shutdowns. After restarting the pump, the dripping reduced, but it continued to occur, though the amount of leakage was not significant.
The demineralized water system is equipped with a filter; air is exhausted before the pump starts operating, and there should be no vacuum conditions during operation. However, since the first shutdown after the mechanical seal was installed (about 1 month ago), dripping from the outer side of the seal was observed during shutdowns. After restarting the pump, the dripping reduced, but it continued to occur, though the amount of leakage was not significant.
The specific pressure on the atmospheric side end face isn’t sufficient; try increasing the pressure of the circulating fluid.
:Lol, I’m asking about the Saintyin vertical high-speed pumps – their seals often leak for no apparent reason, and it’s difficult to identify the exact cause
The preliminary estimate is that the external mechanical seal may be damaged; the specific cause needs to be determined by considering the conditions of the medium, as well as the pressure and temperature levels, including those of the deionized water