Brake pneumatic valve elasticity soft seal and hard seal of distinction

and structural mechanism:
is between metal and metal hard seal seal, seal ball and pneumatic valve seat are metals. The machining accuracy and process is difficult, generally used in high pressure, usually more than MPa. Soft seal is sealed between the metal and nonmetal, such as nylon tetrafluoroethylene, manufacturing standards are the same.
and sealing material:
the elastic pneumatic soft sealing gate valve pneumatic and hard seal gate valve for pneumatic seat sealing material, hard seal is to use pneumatic seat materials precision machining, assurance and pneumatic valve core ( A sphere) The matching accuracy, generally speaking, there are stainless steel and copper. Soft seal is set in the pneumatic sealing material on the seat of non-metallic materials, because of the soft sealing material has certain elasticity, therefore hard seal will be relatively low demands on machining accuracy.
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on manufacturing process due to a lot of chemical industry, machinery industry work environment is more complex, many of them are high temperature and high pressure, the medium of frictional resistance is big, strong corrosion. Now technology progress, all kinds of materials used is better, can keep up with all the aspects of processing, make hard seal ball pneumatic valve widely promoted. Actually hard seal ball principle and soft sealing pneumatic valve is the same, just because is sealed between the metal, to consider the relationship between the hardness of metal, as well as the working condition, what medium, etc. Are generally required to do hardening treatment, between the ball and pneumatic seat to grinding to the seal. Pneumatic valve production cycle is long, hard seal ball processing is more complex, hard seal ball pneumatic valve is not easy to do.
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on the conditions of use soft seal generally seal can achieve very high, while hard seal according to the requirements can be high to low. Soft seal need to fire prevention, because at high temperatures, soft sealing material will leak, and hard seal is not the problem. Hard seal generally can do high pressure, soft seal is not. Soft seal due to the problem of flow medium, some occasions is can't use, Some corrosive medium, for example) 。 The last hard seal generally more expensive than soft sealing pneumatic valves. In manufacturing, both difference is not big, mainly is the difference between pneumatic valve seat, non-metallic, soft seal is is metal hard seal.
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on equipment selection of soft and hard seal ball pneumatic valve is chosen mainly according to the process medium, temperature and pressure, average temperature wear or the medium containing solid particles or above degree had better choose hard seal, diameter greater than the pneumatic valve pressure difference is bigger also consider open pneumatic valve torque size, large torque should be chosen when fixed pneumatic valve, hard seal ball seal level for both hard and soft seal can be achieved.