Mechanical seal wear and service life1

1. About the service 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, such as the graphite friction pair with a balance coefficient of 0.75, the wear amount per hour in water and oil It is about 0.1 micron, that is to say, the wear amount of continuous operation for 10,000 hours is about 1 mm. It can be seen that the wear amount of the friction pair generally does not affect the life of the mechanical seal. Mechanical seals can generally be used continuously for 1 to 2 years, and in some cases, they can be used for 5 to 10 years without any problem. The premise of the above-mentioned life is that the mechanical seal operates under the allowable working conditions, such as shaft movement, beating, medium particle concentration, temperature, corrosion and other factors.

External factors affecting the life of mechanical seals:

1. The pump shaft has a large amount of movement

2. The axial force is too large

3. The disturbance of the pump shaft is too large

4. The auxiliary flushing system is unreasonable

Second, about the standard of leakage

my country's JB4127.1-1999 'Technical Conditions for Mechanical Seals' stipulates: 'In the case of reasonable selection and correct installation and use, when the sealed medium is clean water, oil and similar media, the service life of the mechanical seal is generally Not less than 1 year. When the medium to be sealed is a corrosive medium, the service life of the mechanical seal is generally 6 months to 1 year. However, when the use conditions are harsh, it is not limited. 'Sealing test, average leakage axis ( When the outer diameter of the shaft (or shaft sleeve) is greater than 50mm, it shall not exceed 5mL/h, and when the outer diameter of the shaft (or shaft sleeve) is not greater than 50mm, the leakage shall not exceed 3mL/h.