1. End face eccentricity:
General mechanical seal, its center of the moving ring, the center of the static ring and the center line of the shaft are all in a straight line. If the center of the end face of the moving ring or a ring in the static ring is made to offset the center line of the shaft by a certain distance, it can make the ring continuously bring lubricating fluid into the sliding surface for lubrication during rotation.
It should be pointed out that the eccentric size should not be too large, especially for high pressure, the eccentric will make the pressure on the end face uneven, resulting in uneven wear. For high speed seal, it is not suitable to use the moving ring as the eccentric ring, otherwise the machine will vibrate due to the balance of centrifugal force.
2. End face slotting:
It is difficult for high pressure and high speed machines to keep the liquid film between the friction surfaces. The liquid film is often damaged by the friction heat that generated by high pressure and high speed. In this case, slotting to strengthen lubrication is very effective. The moving ring and the static ring can be slotted, generally on the more wear-resistant material. The moving ring and the static ring should not be slotted at the same time, because this will reduce the lubrication effect. In order to prevent dirt or debris from entering the friction surface as much as possible, the flow of liquid in the direction of centrifugal force (outflow type) should be sealed , the groove shall be opened on the static ring to avoid dirt from entering the friction surface under the effect of centrifugal force. On the contrary, when the liquid flows against the direction of centrifugal force (internal flow), the groove should be opened on the moving ring, and the centrifugal force is helpful to throw the dirt out of the groove.
The small grooves on the friction surface are rectangular, wedge-shaped, or other shapes. The groove should not be too much or too deep, otherwise the leakage will increase.
3. Hydrostatic lubrication:
Hydrostatic lubrication is to introduce the pressure lubricating liquid directly into the friction surface for playing the role of lubrication. The introduced lubricating liquid is supplied by a separate liquid source, such as hydraulic pump. With this kind of pressure lubricating fluid, it is against the fluid pressure in the machine, which is also called hydrostatic seal.
Measures should be taken to establish gas film lubrication for the mechanical seal of gas medium. For example, the gas static pressure controlled film mechanical seal or solid lubrication should be used, that is to say, the self-lubricating material should be used as the driving ring or static ring. As long as conditions permit, the gas medium conditions should be converted into liquid medium conditions as far as possible, so as to facilitate lubrication and sealing.