1. The new one is better than the old one
Relatively speaking, the use of new mechanical seals for vertical pipeline centrifugal pumps is more effective than the old ones. However, if the quality or material selection of the new mechanical seal is not appropriate and there is a larger dimensional error, it will affect the sealing effect; In polymeric and permeable media, it is better not to replace the static ring if there is no excessive wear. Because the stationary ring remains in a stationary state for a long time in the stationary ring seat, the polymer and impurities deposit together, providing a good sealing effect.
2. Dismantling and repairing is better than not dismantling at all
Once a mechanical seal leakage occurs, it is urgent to dismantle and repair it. In fact, sometimes the seal is not damaged, and only adjusting the working conditions or appropriately adjusting the seal can eliminate the leakage. This not only avoids waste but also verifies one's fault diagnosis ability, accumulates maintenance experience, and improves the quality of maintenance.
3. The greater the compression of the spring, the better the sealing effect
In fact, excessive compression of the spring in a vertical pipeline centrifugal pump can cause rapid wear and instant burning of the friction pair; Excessive compression causes the spring to lose its ability to adjust the end face of the moving ring, resulting in seal failure.
4. The tighter the dynamic ring seal diagram, the better
Actually, tightening the dynamic ring seal is harmful and not beneficial. Firstly, it exacerbates the wear of the sealing ring and shaft sleeve, leading to premature leakage; Secondly, it increases the resistance to axial adjustment and movement of the moving ring, making it difficult to make timely adjustments when working conditions change frequently; Thirdly, the spring is prone to damage due to excessive fatigue; The fourth is to deform the sealing ring of the moving ring, which affects the sealing effect.
5. The tighter the static ring seal, the better
The static ring seal is basically in a static state, and a relatively tight seal will have better sealing effect, but being too tight is also harmful. One is to cause excessive deformation of the static ring seal, which affects the sealing effect; The second reason is that the material of the static ring is mostly graphite, which is generally brittle and prone to cracking under excessive stress; Thirdly, installation and disassembly are difficult, and the static ring is easily damaged.
6. The tighter the impeller lock nut, the better
In mechanical seal leakage, leakage between the shaft sleeve and the shaft (inter shaft leakage) is quite common. It is generally believed that inter shaft leakage is caused by the impeller locking nut not being tightened. In fact, there are many factors that can lead to inter shaft leakage, such as the failure and displacement of the inter shaft gasket, impurities in the inter shaft, significant positional errors at the fit between the shaft and the shaft sleeve, damage to the contact surface, gaps between various components on the shaft, and excessively long screw threads on the shaft head, all of which can cause inter shaft leakage.
Excessive locking of the locking nut of a vertical pipeline centrifugal pump will only lead to premature failure of the shaft gasket. On the contrary, moderate locking of the locking nut can maintain a certain degree of compression elasticity of the shaft gasket. During operation, the locking nut will automatically and timely lock, ensuring that the shaft gasket is always in a good sealing state.
