Seal selection, considering the working conditions, so as to choose the appropriate seal form and material, installation structure. The operating conditions to be considered generally include: temperature, pressure, medium. Other needs to be combined with the characteristics of the equipment itself to consider the selection. About the temperature, such as NBR material working temperature fan mechanical seals generally in the range of -40 ~ +120℃. If the temperature exceeds 120℃, FKM should be considered, even PTFE material. Generally speaking, the use of cold resistant NBR should be considered in the case of -20 ~ -40℃. Generally speaking, NBR materials in the low temperature environment will lead to the material hardening, leading to leakage. For example, railway locomotives often have such problems in the winter in the north. As for pressure, it affects the type of seal to choose.
  Generally speaking, the selection of low pressure rubber or PU seal will not have too much problem. However, there is a problem of impact pressure to be considered. For example, when the construction machinery is started and closed, its impact pressure is much higher than the normal working pressure, so the impact and extrusion resistance HBY mechanical seal or SPGW, which can withstand pressure up to 70MPA, is often selected as the main seal. PTFE combination seals are also a common option. The medium problem is relatively simple. There are just a few special issues to look out for, such as hydro-ethylene glycol and phosphate ester hydraulic fluids that are often used in metallurgical industry cylinders. Sometimes, although the working temperature is not high, the selection of materials should be very careful, and FKM should be used for hydraulic oil when the latter is adopted. The selection of seals is very important, or combined with the situation of the equipment to choose. For example, you need to be responsive, control and of course choose the stefanegele circle. In need of high reliability, GD1000K series of hongge or SPGW of NOK are often selected. For example, the field work of construction machinery often has shock and cold weather, its dust ring will choose exposed metal framework to avoid falling off. Cylinders, compressor piston rings, high pressure oil seals, and pumps used in scientific instruments all require special structures for their seals.


What is the general knowledge of seal selection?

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