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Home - News - Misunderstandings in overhauling mechanical seals for pumps and correct overhaul methods

Misunderstandings in overhauling mechanical seals for pumps and correct overhaul methods

December 9, 2021



     1. The larger the spring compression, the better the sealing effect. In fact, it is not the case. Excessive compression of the spring can lead


to rapid wear of the friction pair and instant burnout; excessive compression makes the spring lose its ability to adjust the end face of the


moving ring, resulting in seal failure. So choose the appropriate spring compression.


     2. The tighter the dynamic ring seal, the better. In fact, too tight a dynamic ring seal is harmful and useless. One is to aggravate the wear


between the seal ring and the shaft sleeve, and to leak prematurely; the second is to increase the resistance of the axial adjustment and


movement of the moving ring, which cannot be adjusted in a timely manner when the working conditions change frequently; the third is that


the spring is excessively fatigued and easily damaged; It deforms the moving ring sealing ring and affects the sealing effect.


    3. The tighter the static ring seal, the better. The static ring sealing ring is basically in a static state, and the sealing effect will be better if it is


relatively tight, but too tight is also harmful. One is that the static ring seal is excessively deformed, which affects the sealing effect; the second


is that the static ring is mostly made of graphite, which is generally brittle, and excessive force is very easy to cause fragmentation; the third is


that it is difficult to install and disassemble, and it is easy to damage the static ring.


    4. The tighter the impeller lock nut, the better. In the mechanical seal leakage, the leakage between the sleeve and the shaft (inter-shaft


leakage) is relatively common. It is generally believed that the leakage between the shafts means that the impeller lock nut is not locked. In


fact, there are many factors that lead to the leakage between the shafts, such as the failure of the shaft pads, offset, impurities in the shafts,


and larger shapes in the joints between the shafts and the shaft sleeves. Position errors, damage to the contact surface, gaps between parts


on the shaft, and excessively long shaft head threads will cause leakage between the shafts. Over-tightening of the lock nut will only cause


premature failure of the inter-axial pad. Therefore, as long as the lock nut is properly locked, the pad between the shafts will always maintain a


certain compression elasticity, and the lock nut will be automatically locked in time during operation, so that the shaft is always in a good


sealing state.


     5. The new one is better than the old one. Relatively speaking, the effect of using the new mechanical seal is better than the old one, but


the quality or material of the new mechanical seal is improperly selected, and the large size error of the fit will affect the sealing effect; in


polymerizing and permeable media, the static ring is not excessive Worn, it is better not to replace. Because the static ring stays in a static


state for a long time in the static ring seat, the polymer and impurities are deposited as a whole, which has a better sealing effect.


     6. Dismantling is better than no dismantling. Once the mechanical seal leaks, it is eager to dismantle and repair. In fact, sometimes the seal


is not damaged, and the leakage can be eliminated by adjusting the working conditions or properly adjusting the seal. In this way, it can not


only avoid waste but also verify its own fault judgment ability, accumulate maintenance experience and improve the quality of maintenance.