Leakage of mechanical seal-

Leakage of mechanical seal
　2017-07-20　　
Leakage Q of mechanical seal:
The leakage Q of a mechanical seal refers to the total amount of the sealed medium that leaks through the end seal pair and the auxiliary seal per unit time, and is the most important performance parameter of the mechanical seal. The leakage of the mechanical seal is caused by many factors. According to statistics, 80% to 90% of the leakage in the contact mechanical seal is caused by the end face seal pair. The leakage of the end face seal pair is mainly determined by the friction state between the sealing faces. Therefore, in order to ensure the reliability of the seal, long life and small leakage, the end face of the seal must be in the best lubrication state when working. National standard 103B water pump mechanical seal
When the end face of the seal is in a fluid lubrication state, the leakage Q usually introduces a correction coefficient according to the radial slit internal flow formula, namely

In the formula-the average thickness of the fluid film on the end face,;
－－Leak correction coefficient considering various factors It can be seen from the above formula that the leakage of the seal in the fluid lubrication state is proportional to the average diameter and pressure difference, proportional to the third power of the average film thickness of the sealing surface, and proportional to the viscosity of the medium and the sealing surface The width is inversely proportional. It can be seen that the average film thickness of the sealing surface has a greater impact on the leakage Q.
When the sealing end face is in a state of mixed lubrication, Meyer proposed that the leakage Q can be calculated according to the following empirical formula. which is


When the sealing end face is in the boundary lubrication state, Meyer proposed that the leakage Q can be calculated according to the following empirical formula. which is:

In the formula, S-gap coefficient, its value increases sharply with the increase of the circumferential velocity v of the seal end face and tends to a certain value at high circumferential velocity. The relationship between S and v is shown in Figure 1-11.

For contact mechanical seals, my country’s JB/T4127.1-1999 'Technical Conditions for Mechanical Seals' stipulates: When the sealed medium is liquid, the average leakage is specified as follows:
When the outer diameter of the shaft (or sleeve) is greater than 50mm, it shall not be greater than tml/h;
When the outer diameter of the shaft (or sleeve) is not more than 50mm, it is not more than 3ml/h.
For special conditions and when the sealed medium is a gas, it is not subject to this limit.　　539.html,

The amount of wear of the mechanical seal 　 　 the friction power consumption of the mechanical seal