During decarburization processes the vacuum system must operate very long time in a rough pressure range. A competent gas-cooling is necessary as the extracted hot gases would otherwise overheat the filter and vacuum system.
With the development of technology and the improvement of item quality in aerospace, electric power, iron and steel digesting, pharmaceutical and chemical industries, these industries have to obtain a particular vacuum environment. Simultaneously, the vacuum system utilized by these industries is usually continuously raising, and the vacuum degree is continuously increasing. Furthermore, the state’s environmental protection, energy conservation and three wastes discharge to the above-described industries, etc. Gas-Cooling Roots Pump Certain requirements are more stringent. At present, the prevailing dry vacuum pumps out there, such as for example screw vacuum pumps and claw vacuum pumps, cannot meet the requirements of oil-free large 
pumping rate clean vacuum environment proposed by these industries due to the restrictions of pumping acceleration characteristics and structural system.
In view of the shortcomings of the existing technology, the specialized 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 large oil-free pumping speed.