Analysis and modification of frequent leakage in mechanical seals
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The mechanical seal of the catalytic P204AB gasoline top circulation pump in our factory leaks frequently; the seal has to be replaced every 1–2 months. Upon opening the old seal, it was found that its interior as well as the moving and stationary rings were quite dirty. The mechanical seal is flushed automatically, with a small heat exchanger in the self-flushing pipeline for cooling. The reason for the frequent leakage of the mechanical seal is that the flushing fluid used for it is too dirty. We plan to install a filter in front of the self-flushing heat exchanger; do you think this is a viable solution? Please share your opinions.
Improving the operating conditions of mechanical seals is certainly effective in extending their service life
If it is led from the pump outlet, passes through a heat exchanger and then to the sealing chamber, it is PLAN21; adding a filter results in PLAN22. If a filter is used, two filters need to be connected in parallel, with a valve placed before and after each filter. Regularly switch and clean the filter.
With the self-flushing mechanism removed, how long can a pump like this operate?； What will be the effect of a cryopump without self-flushing?
If the problem described by the poster occurs frequently, I think it is generally caused by two reasons: 1. High temperature. 2. The rinse solution is too dirty. It is recommended to change the flushing method to P32
Rinsing dirt will definitely affect the service life of the mechanical seal. Even with filters in place, there is a risk that they may go unnoticed during inspections, leading to insufficient flushing fluid and damage to the mechanical seal. External flushing is recommended
Check if the self-cleaning is still working If the outlet of the cooler is cold, it is most likely that the flushing pipeline is blocked, causing the flushing to be interrupted. One can try to enlarge the orifice plate to increase the heat exchange area of the cooler, and install dual filters in the flushing pipeline to reduce the accumulation of fouling on the pipe walls. As long as the flushing volume and temperature can be maintained, the sealing environment is improved and the service life is extended.
After passing through the heat exchanger, the pipeline for flushing the mechanical seal of this pump is sometimes at no temperature, indicating that the flushing flow has become blocked. I would like to ask how long a mechanical seal usually lasts under such conditions, and what impact flushing has on the mechanical seal in this environment, with or without flushing.
If the liquid being transported isn’t clean, why use self-flushing? Switching to external flushing will fundamentally solve the problem
What material are the static and dynamic rings made of? The medium contains impurities, so graphite rings cannot be used. What is the condition of the rings after disassembly, and what is the condition of the O-rings?
Also, are small springs used as the elastic elements in the mechanical seal? Is spring protection in place? Possible reasons: 1. The small spring lacks spring protection, which prevents it from providing compensation and results in the ring surface opening. 2. The wrong material was chosen for the moving ring O-ring; the O-ring swells and deforms, which prevents the moving ring from performing its compensatory function, leading to leakage at the location of the O-ring. 3. The materials of the stationary and rotating rings are incorrect; impurities are present, and graphite rings cannot be used. These are roughly the issues.