Mechanical seal for kettle Advantages and disadvantages of
1. Advantages
(1) The structure is reliable, and the leakage can be limited to a small amount. As long as the surface roughness and straightness of the main sealing surface can meet the requirements, and as long as the wear resistance of the material is good, the mechanical seal can achieve a small amount of leakage, or even the leakage can not be seen by the naked eye.
(2) Long life. In mechanical seals, the main wear part is the end face of the seal friction pair. Because the wear amount of the seal end face is not large under normal working conditions, it can be used continuously for 1 to 2 years in general, and for 5 to 10 years in special occasions.
(3) No adjustment is required during operation. Since the mechanical seal relies on spring force and fluid pressure to make the friction pair stick together and automatically keep contact during operation, it is unnecessary to adjust and compress it like ordinary soft packing after assembly.
(4) It is resistant to vibration. The maximum amplitude does not exceed 0.05mm at the speed of 3000r/min, and the PV value increases continuously
(5) Small power loss. The packing seal works on the shaft or shaft sleeve by the packing. The packing seal directly rubs against the shaft. The tighter the packing is, the greater the friction and power consumption will be. The friction of mechanical seal is in the state of half liquid friction, and the friction coefficient is very small. The power loss of mechanical seal is 10~50% of that of packing seal
(6) The bellows seal shaft or shaft sleeve is not worn, and is not sensitive to the vibration of the rotating shaft and the deflection of the shaft to the housing.
(7) Wide application range. When the medium is flammable, explosive, toxic and harmful, mechanical seal can ensure the sealing. It is also suitable for sealing equipment with high temperature, low temperature, high pressure, vacuum and various rotating speeds and corrosive media.
2. Disadvantages
(1) For example, the structure is more complex than the packing seal, the processing precision is required, and certain installation technology is required, especially the installation of dry gas seal. Moreover, the sealing technology has developed rapidly, and the new technologies have brought us new topics for maintenance.
(2) Complex structure and inconvenient disassembly. Compared with other seals, mechanical face seals have many parts, precise requirements and complex structures. Especially, it is difficult to assemble. When disassembling and assembling, the sealing ring should be pulled out from the shaft end, and the machine part (coupling) or all must be disassembled. At present, some improvements have been made to this problem, for example, the split type and Cartridge mechanical seal Etc.
