Five basic points that sealing packing materials in the machinery industry should possess
In the mechanical industry, packing seals are mainly used as dynamic seals. It is commonly used as the shaft seal for centrifugal pumps, compressors, vacuum pumps and agitators. In the design and selection of packing seals, the working conditions of mechanical equipment should be the main consideration. The selection of packing should take into account the following conditions:
It has a certain degree of plasticity and can generate a certain radial force under the action of clamping force and come into contact with the tight shaft.
2. It should have sufficient chemical stability, not contaminate the medium, the packing should not be swollen by the medium, the impregnating agent in the packing should not be dissolved by the medium, and the packing itself should not corrode the sealing surface.
3. The packing material has good self-lubricating performance, is wear-resistant and has a low coefficient of friction.
When there is a slight offset of the shaft, the packing should have sufficient floating elasticity.
5. Simple to manufacture and convenient to fill.
For this reason, it is necessary to frequently adjust the compression degree of the packing, so that after the lubricant in the packing has been running for a period of time and has been lost to some extent, some lubricant can be squeezed out, while compensating for the relaxation of the compression force caused by the volume change of the packing. Of course, such frequent squeezing of the filler will eventually deplete the impregnating agent, so it is necessary to replace the filler regularly. In addition, in order to maintain the liquid film and remove frictional heat, it is also necessary to intentionally allow a small amount of leakage at the packing.
