During decarburization procedures the vacuum system must operate long time in a rough pressure range. A competent gas-cooling is essential as the extracted warm gases would otherwise overheat the filter and vacuum program.
With the development of technology and the improvement of item quality in aerospace, energy, iron and steel processing, pharmaceutical and chemical industries, these industries need to obtain a certain vacuum environment. At 
the same time, the vacuum system used by these industries is continuously increasing, and the vacuum degree is continuously increasing. Furthermore, the state’s environmental protection, Gas-Cooling Roots Pump energy saving and three wastes discharge to the above-described industries, etc. The requirements are more stringent. At present, the existing dry vacuum pumps out there, such as screw vacuum pumps and claw vacuum pumps, cannot meet up with the requirements of oil-free large pumping velocity clean vacuum environment proposed by these industries because of the restrictions of pumping rate characteristics and structural mechanism.
In view of the shortcomings of the prevailing technology, the technical problem to be solved by the utility model is to provide an all-gas-cooled vacuum system to satisfy the use in a clean vacuum environment with huge oil-free pumping speed.