Questions about mechanical seals
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Hi friends, I recently learned* I can probably understand the principles of mechanical and dry sealing, but one thing I still don’t understand is how the contact surface between the shaft and the seal is guaranteed not to leak, as shown in the picture
Just in your picture, isn't there a black sealing ring on it?
4 is the main leakage channel, the end face of the two sealing rings. The end faces of these two rings are very flat and there is a thin liquid film in between. Mechanical seals cannot ensure that the medium is completely leak-free, but only limit the amount of leakage. A single-end mechanical seal can ensure that the leakage of process media is below 1000ppm.
It is component 3. It is an O-ring or other shaped annular seal, which is elastic, so that the inner diameter surface of the seal is in contact with the shaft, and the outer diameter surface is in sealing contact with other sealants to achieve the sealing effect.
There is a typo above. The outer diameter of the annular seal is in contact with 4 in the picture. Due to the elastic compensation function of the seal, the medium does not leak or the leakage amount is within the allowable range.
Are you referring to the sealing ring "3"?
"3" in the picture represents elastic rubber ring； Material can be rubber or PTFE
3 is the sealing ring, which can play the role of sealing with the shaft
The function of the seal is to prevent the medium from leaking into the atmosphere, or to prevent atmospheric gas from entering the pump. The red part in the picture is the medium. The left side is the sealing chamber filled with media, the right side is the sealing gland, and further to the right is the atmosphere. If you look carefully at 3, the 3 sealing ring plays a sealing role between the shaft and the moving ring. The white part on the left of 3 is the atmosphere, which is the circumferential gap between the shaft and the moving ring. It is the 3 sealing ring that seals the shaft and the moving ring to prevent the medium from leaking into the atmosphere through 3.