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Several Misunderstandings In The Mechanical Seal Inspection Of Pumps
- Oct 18, 2018 -

1. The greater the amount of spring compression, the better the sealing effect. In fact, if the spring compression amount is too large, the friction pair may be sharply worn and burned instantaneously; excessive compression causes the spring to lose the ability to adjust the end face of the moving ring, resulting in seal failure.

2. The tighter the moving ring seal is, the better. In fact, the dynamic ring seal is too tight and harmful. First, the wear between the seal ring and the bushing is intensified, and the leakage is premature; secondly, the resistance of the moving ring in the axial adjustment and movement is increased, and the adjustment cannot be made timely when the working conditions change frequently; the third is that the spring is excessively fatigued and easily damaged; It is to deform the moving ring seal and affect the sealing effect.

3. The tighter the static ring seal, the better. The static ring seal is basically at rest, and the relatively tight seal will be better, but too tight is also harmful. First, the static ring seal is caused by excessive deformation, which affects the sealing effect. Secondly, the static ring material is mostly graphite, which is generally brittle. Excessive force is easy to cause chipping. Third, it is difficult to install and disassemble, and it is easy to damage the static ring.

4. The tighter the impeller lock is, the better. In mechanical seal leaks, leakage between the bushing and the shaft (interaxial leakage) is more common. It is generally believed that the leakage between the shafts is that the impeller locks are not locked. In fact, there are many factors causing leakage between the shafts, such as the failure of the inter-axis pads, the offset, the impurities between the shafts, and the larger shape of the shaft and the sleeve. Position errors, contact surface damage, gaps between components on the shaft, and excessive length of the shaft threads can cause leakage between the shafts. Excessive locking of the lock nut will only lead to premature failure of the inter-axis pad. On the contrary, the lock nut is moderately locked, so that the inter-axis pad always maintains a certain compression elasticity. During operation, the lock nut will automatically lock in time, so that the shaft is always in good condition. Sealed state.

5. The new one is better than the old one. Relatively speaking, the effect of using a new mechanical seal is better than that of the old one, but the quality or material selection of the new mechanical seal is not appropriate. The large dimensional error will affect the sealing effect; in the polymerizable and permeable medium, the static ring is not excessive. Wear or not replace it as well. Because the static ring is in a static state for a long time in the static ring seat, the polymer and impurities are deposited as one body, which has a good sealing effect.

6. The repair is better than not. In the event of a mechanical seal leak, it is urgent to dismantle. In fact, sometimes the seal is not damaged. It is only necessary to adjust the working condition or properly adjust the seal to eliminate the leak. In this way, it avoids waste and can verify its own fault judgment ability, and accumulates maintenance experience to improve the quality of maintenance.