The Role of Mechanical Seals

1、Advantages

    （1） The structure is reliable, the leakage can be limited to very little, as long as the surface roughness and straightness of the main sealing surface can ensure that the requirements are met, as long as the material has good wear resistance, the mechanical seal can achieve very little leakage, and even the naked eye can not see the leakage.

    （2）Long life. In the mechanical seal, the main wear part is the seal friction pair end face, because the wear of the seal end face is not large under normal working conditions, it can generally be used continuously for 1 to 2 years, and it is also useful to 5 to 10 years in special occasions.

    （3）No adjustment in operation. Because the mechanical seal relies on the spring force and fluid pressure to make the friction pair fit, it automatically maintains contact during operation, and does not need to be adjusted and pressed like ordinary soft packing after assembly.

    （4）It has vibration resistance. The maximum amplitude does not exceed 0.05mm at a rotational speed of 3000r/min and the PV value is continuously improved.

    （5）Low power loss. The packing seal works on the shaft or sleeve by pressing the packing. The packing seal has direct friction with the shaft, and the tighter the packing pressure, the greater the friction and the greater the power consumption. The friction of the mechanical seal is in a semi-liquid friction state, the friction coefficient is very small, and the power loss of the mechanical seal is 10 ~ 50% of the packing seal.

    （6）The bellows seal shaft or shaft sleeve is not worn, and is not sensitive to the oscillation of the rotating shaft and the deflection of the shaft to the housing.

    （7）A wide range of applications. When the medium is flammable, explosive, toxic and harmful, the mechanical seal can ensure the sealing. It is also suitable for high temperature, low temperature, high pressure, vacuum various speed and corrosive media equipment seal.

2、Disadvantages

    （1）For example, the structure is more complex than the packing seal, the processing accuracy is high, and certain installation technology is required, especially the installation requirements of the dry gas seal are higher. And the development of sealing technology is very fast, and the emergence of new technologies has brought new issues to our maintenance.

     （2）The structure is complicated and the disassembly is inconvenient. Compared with other seals, the mechanical end seal has a large number of parts, requiring precision and complex structure. Especially in the assembly is more difficult, disassembly to extract the seal ring from the shaft end, must be part of the machine (coupling) or all disassembly. At present, some improvements have been made to this problem, such as the use of split and pack mechanical seals that are easy to disassemble and ensure assembly quality.