204 Mechanical seal What are some mistakes that should be paid attention to during maintenance?
1. The greater the spring compression, the better the sealing effect. In fact, the spring compression is too large, which can lead to rapid wear and instant burning of the friction pair; Excessive compression makes the spring lose the ability to adjust the end face of the moving ring, leading to seal failure.
2. The tighter the dynamic ring seal diagram, the better. In fact, the moving ring seal ring is too tight and harmful. One is to intensify the wear between the seal ring and the shaft sleeve, causing premature leakage; The second is to increase the resistance of axial adjustment and movement of the moving ring, which can not be adjusted timely when the working conditions change frequently; Third, the spring is easily damaged due to excessive fatigue; The fourth is to deform the dynamic ring seal ring, which affects the sealing effect.
3. The tighter the stationary ring seal, the better. The static ring seal ring is basically in a static state, and the sealing effect will be better if it is relatively tight, but it is also harmful if it is too tight. First, it causes excessive deformation of the static ring seal and affects the sealing effect; Second, the stationary ring is mostly made of graphite, which is generally brittle and easy to be broken under excessive stress; Third, it is difficult to install and disassemble, and the stationary ring is easily damaged.
4. The tighter the impeller locknut, the better. In the leakage of mechanical seal, the leakage between shaft sleeve and shaft (leakage between shafts) is relatively common. It is generally believed that the leakage between shafts is the failure of the impeller locknut to lock. In fact, there are many factors that lead to the leakage between shafts, such as the failure and deviation of the inter shaft gasket, impurities in the inter shaft, large form and position errors at the fitting between the shaft and the shaft sleeve, damage to the contact surface, gaps between the components on the shaft, and too long screw lines on the shaft head. Excessive locking of the lock nut will only lead to premature failure of the inter axle gasket. On the contrary, lock the lock nut properly to keep the inter axle gasket always with certain compression elasticity. During operation, the lock nut will automatically lock in time to keep the inter axle gasket always in a good sealing state.
5. The new is better than the old. Relatively speaking, the effect of using the new mechanical seal is better than the old one, but the quality or material selection of the new mechanical seal is not appropriate, and the matching size error will affect the sealing effect; In polymerizable and permeable media, it is better not to replace the stationary ring if there is no excessive wear. Because the stationary ring is in a static state for a long time in the stationary ring seat, the polymer and impurities are deposited together, playing a better sealing role.
6. It is better to repair than not. Once the mechanical seal leaks, it is urgent to disassemble and repair it. In fact, sometimes the seal is not damaged, and only needs to adjust the working condition or properly adjust the seal to eliminate the leakage. This can not only avoid waste, but also verify their fault judgment ability, accumulate maintenance experience and improve maintenance quality.
