During decarburization processes the vacuum system needs to operate long time in a rough pressure range. A competent gas-cooling is essential as the extracted hot gases would otherwise overheat the filter and vacuum program.
With the development of technology and the improvement of product quality in aerospace, electric power, iron and steel processing, pharmaceutical and chemical industries, these Gas-Cooling Roots Pump industries need to obtain a particular vacuum environment. At the same time, the vacuum system utilized by these industries is continuously raising, and the vacuum level is continuously increasing. Moreover, the state’s environmental safety, energy conservation and three wastes discharge to the above-pointed out industries, etc. The requirements are more stringent. At the moment, the prevailing dry vacuum pumps on the market, such as screw vacuum pumps and claw vacuum pumps, cannot meet up with the requirements of oil-totally free large pumping swiftness clean vacuum environment proposed by these industries because 
of the restrictions of pumping rate characteristics and structural system.
In view of the shortcomings of the prevailing technology, the technical problem to be solved by the utility model is to supply an all-gas-cooled vacuum system to satisfy the use in a clean vacuum environment with large oil-free pumping speed.