Packing Seal is one of the most ancient seal, in China have had a thousand years of history. It was originally to cotton, the fiber packing Ma leak in the flow channel to prevent leakage, mainly for water to the mechanical seal.
Mainly used as a packing seal dynamic seal. It is widely used as centrifugal pumps, compressors, vacuum pumps, mixers and the ship's propeller shaft seal, reciprocating compressor, refrigerator seal the reciprocating motion, as well as the rotating valve stem seals, etc.. In order to adapt to the working conditions of the equipment, packing seal must meet the following requirements:
1) a certain degree of plasticity, the clamping force can produce some radial force and close contact with the shaft.
2) there is sufficient chemical stability, and less pollution medium, medium foam filler is not bulging, fill in the stain of transgression was not dissolved media, do not fill sealing surface corrosion.
3) Self-lubricating properties of a good, wear, friction factor small.
4) the presence of small amounts eccentric shaft, the filler should be sufficient flexibility floating.
5) create simple, convenient filling.
Many of the types of fillers, from the function, structure and material aspects of classification, the most common are the following four categories: Stranded filler, filler for guitar, plastic filler, filler metal.
Stranded for a guitar and filler packing
   Stranded filler that is, several asbestos-Stranded together, it will be filling in the cavity filler can be sealed from the role.
   Fill a guitar for cotton, as well as asbestos fibers Ma spinning lines for guitar from, and which penetrated lubricant or PTFE. .2 Plastic filler
   After packing plastic film is a suppressed molding respectively.
3 metal filler
   Fill a metal-metal and metal filler packing two. The so-called semi-metal filler is a combination of metal and non-metallic, non-metal, non-metallic fillers.
4 carbon fiber filler
   Carbon fiber is a new filler packing. Self-lubricating its excellent performance, high resistance, low temperature performance, and chemical resistance properties attract a lot of attention, and as a compression packing flexibility and softness also very good, the drawback is that there are only infiltration leaks, but transgression stain - Tetrafluoroethylene or other bonding agent after can prevent. Its current high cost, but with the development of carbon fiber, and the cost will decrease, therefore, carbon fiber filler is one of the most ideal and the most promising filler. `
5 filler choice
    Packing options should be considered when: machine types, media physics, chemistry, temperature and pressure, and velocity, and so on, particularly in the areas of the corrosive medium (pH value that), pH and temperature for the important.
6 reasonable filler loading
    Filler loading shall be reasonable steps:
1) Fill cavity clearance check whether there is a shaft surface scratches, Burr phenomenon.
2) Using Dial Indicator inspection shaft seal parts of the radial variation of its tolerance should be allowed limits.
3) Fill cavity and the shaft surface should be coated with sealant or the media would like to meet sealants.
4)% vol packaging materials should be used to take a shaft with the same size stick, fill in its winding, again with a knife cut, and the best was 450 slant incision, cut off after each section filler, it should not be loose, it should not be realigned, and should take the same width and fill each section of the tapes to fill a circle-shaped bandage, and the place clean.
5) should be filled loading lap lap, not at the same time filled laps.
6) and take a strong filler wood with the size of the two semi-bushings are in the axis, will be packing into the deep cavity, and the wood used gland bushings exerting certain pressure to be pre-compression packing.
7) the same way filled second round, third round.
8) the final lap after the filler loading, application gland presser, but clamping force should not be too large.