1. Several misconceptions in mechanical seal maintenance
　　
The greater the compression of the spring, the better the sealing effect. In fact, excessive compression of the spring 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.
　　
The tighter the dynamic sealing ring, the better. Actually, tightening the dynamic ring seal is harmful and not beneficial. One is to intensify 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.
　　
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; Secondly, if the material of the static ring is graphite, it is generally brittle and can easily crack under excessive stress; Thirdly, installation and disassembly are difficult, and the static ring is easily damaged.
　　
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 will only lead to premature failure of the shaft pad. On the contrary, moderately locking the locking nut can maintain a certain degree of compression elasticity of the shaft pad, and the locking nut will automatically lock in a timely manner during operation, ensuring that the shaft pad is always in a good sealing state.
　　
The new one is better than the old one. Relatively speaking, the effect of using a new mechanical seal is better than the old one, but the quality or material selection of the new mechanical seal is not appropriate, and larger dimensional errors can 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. In addition to strictly following the installation and use instructions, two points should also be noted when using the water pump:
　　
One is to avoid relying solely on experience. For example, when the bottom valve of a water pump leaks, some operators try to save time by filling the inlet pipe with dry soil before each start-up, and then pouring water to flush the soil to the bottom valve to prevent the bottom valve from leaking. This method may seem simple and easy to implement, but it is not practical enough. Because when the water pump starts working, the sand and soil inside the bottom valve will enter the pump with the water, wear out the impeller, pump casing, and shaft, seriously affecting the service life. The correct method should be to inspect the bottom valve. If it cannot be repaired, it should be replaced. The second is to promptly troubleshoot any faults and avoid letting the unit work while it is sick. For example, if severe wear is found on the packing of the water pump shaft, it is necessary to increase the packing in a timely manner, otherwise it will cause air leakage from the packing of the water pump shaft. Leakage of the water pump shaft packing not only causes excessive energy consumption of the unit, but also leads to cavitation, accelerating the damage of the impeller and directly affecting the service life of the water pump. For example, if a water pump is found to be vibrating violently, it should be stopped immediately for inspection. Otherwise, if the water pump is bent or deformed, it is likely to cause a safety accident.
　　
After a period of use, the water pump unit and pipeline should be well maintained.
　　
(1) Drain the remaining water from the water pump and pipeline.
　　
(2) If disassembly is convenient, the water pump and pipeline can be removed and cleaned thoroughly.
　　
(3) Check the ball bearings, and replace them if the inner and outer sleeves are worn, loose, the ball bearings are worn, or there are spots on the surface. Clean the bearings with gasoline or kerosene and apply butter for storage if they are still usable.
　　
(4) Check whether there are cracks or small holes on the impeller, and whether the impeller fixing nut is loose. If it is damaged, it should be repaired or replaced. Check the clearance at the impeller wear reducing ring. If it exceeds the specified value, it should be repaired or replaced.
　　
(5) If the water pump and pipeline are not disassembled, the outlet should be sealed with a cover plate to prevent debris from entering.
　　
(6) When the transmission tape is not in use, it should be removed, cleaned and dried with warm water, and stored in a place without direct sunlight. It should also not be stored in places with oil stains, corrosive substances, or smoke. Under no circumstances should the tape be contaminated with oily substances such as engine oil, diesel, or gasoline, and do not apply rosin or other viscous substances to the tape. Before using the tape, the powder on the contact surface of the tape must be removed.
　　
(7) Clean all screws and bolts with a wire brush and apply engine oil or soak them in diesel for storage.
　　
In short, in addition to strictly following the instructions for use, it is also necessary to do a good job in repairing and maintaining the water pump in order to extend its service life.