Mechanical seal

Mechanical seal refers to a device for preventing fluid leakage composed of at least one pair of end faces perpendicular to the rotation axis under the action of fluid pressure and elastic force (or magnetic force) of compensation mechanism and the cooperation of auxiliary seal. Elastic loading mechanism and auxiliary seal are the mechanical seals of metal bellows, which we call metal bellows seal. In the light seal, there are also those that use rubber bellows as auxiliary seal. The elastic force of rubber bellows is limited. Generally, it needs to be supplemented by springs to meet the loading elastic force.

Mechanical seal is a shaft seal device of rotating machinery. Such as centrifugal pump, centrifuge, reactor, compressor and other equipment. Since the transmission shaft runs through the inside and outside of the equipment, there is a circumferential gap between the shaft and the equipment, and the medium in the equipment leaks outward through the gap. If the pressure in the equipment is lower than the atmospheric pressure, the air leaks into the equipment. Therefore, there must be a shaft package to prevent leakage. There are many kinds of shaft seals. Because mechanical seals have the advantages of less leakage and long service life, mechanical seals are the most important shaft seals in these equipment in the world. Mechanical seal, also known as end face seal, is defined in the relevant national standards as follows: "it is a device to prevent fluid leakage composed of at least one pair of end faces perpendicular to the rotation axis, which are kept stuck and relatively sliding under the action of fluid pressure, elastic force (or magnetic force) of compensation mechanism and the cooperation of auxiliary seal."

Advantages of mechanical seal:

1. The sealing is reliable. During long-term operation, the sealing state is very stable and the leakage is very small. According to rough statistics, the leakage is generally only 1 / 100 of that of soft packing seal;

2. Long service life, generally up to 1 ~ 2 years or more in oil and water media, and more than half a year in chemical media;

3. The friction power consumption is small, and the friction power of mechanical seal is only 10% ~ 50% of that of soft packing seal;

4. The shaft or shaft sleeve is basically free from wear;

5. The maintenance cycle is long, and the end face can be automatically compensated after wear. Generally, there is no need for regular maintenance;

6. Good vibration resistance, insensitive to the vibration and deflection of the rotating shaft and the deflection of the shaft to the sealing cavity;

7. Wide application range mechanical seal can be used for sealing of low temperature, high temperature, vacuum, high pressure, different rotating speeds, as well as various corrosive media and media containing abrasive particles.

8. Packing can not meet the requirement of "zero leakage" in many factories today; It has a wide application range and greater randomness, but for the factory, frequent replacement or maintenance will cause great losses to the factory.