Water vapor condenses into droplets in the process of contraction and mixes with the pump to form suspension. It not only reduces the vacuum, but also rusts the pump chamber and rotor, destroys the sealing surface and lowers the limit vacuum of the pump. Therefore, it is very important to prevent water vapor from polluting mechanical pumps. The preventive measures include:
(1) Oil-sealed mechanical pumps with air-ballast devices are selected;
(2) Oil separators, centrifugal separators or oil-water separators stop the treatment of mechanical pump oil mixed with water, and the treated oil is then flowed into the pump for use;
(3) Use monotonous agents with strong water absorption;
(4) The use of liquid nitrogen cold trap can not only effectively absorb water vapor, but also prevent the mechanical pump oil from flowing back to the high vacuum chamber.
Pollution and Prevention of Oil Diffusion Pump Vacuum System
The vacuum system of oil diffusion pump is the most widely used vacuum system. Its vacuum degree is 1.3 *10-3~1.3 *10-5 Pa. After long-term use, the common shortcomings of various vacuum devices consisting of oil diffusion pump vacuum system are that the vacuum can not be pumped up, or the vacuum can not be pumped up to the original limit vacuum level. It is related to the oil vapor pollution of the vacuum chamber wall and the pollution of various pollutants in the vacuum process.
(1) Clean the vacuum chamber regularly;
(2) Stop cleaning oil seal mechanical vacuum pump and oil metal diffusion pump regularly.
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