| 摘要 |
PURPOSE:To keep of a counter flow of oily vapor as well as to prevent a vacuum vessel from being polluted by oil, by keeping space between a mechanical booster of a first stage pump of a vacuum device and an oil-sealed rotary vacuum pump of the second stage pump into lower pressure than an achievable vacuum of the oil-sealed rotary vacuum pump by means of gas admixture. CONSTITUTION:A mechanical booster 12, an intermediate vessel 17 and an oil- sealed rotary vacuum pump 11 are all connected to an exhaust system of a vacuum vessel 13 in regular sequence. Inside the intermediate vessel, there are provided with a baffle plate and a cooling pipe and simuotaneously a lead-in pipe 16 taking in gas is connected. Therefore, the inside of the intermediate vessel is kept up in the degree of vacuum being slightly lower than an achievable vacuum of the oil-sealed rotary vacuum pump by means of gas admixture so that oily vapor is stread wide, thus it is prevented from flowing backward inside the vacuum vessel.
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