During decarburization procedures the vacuum system needs to operate very long time in a rough pressure range. An efficient gas-cooling is necessary as the extracted incredibly hot gases would otherwise overheat the filter and vacuum system.
With the development of technology and the improvement of product quality in aerospace, electric power, iron and steel Gas-Cooling Roots Pump digesting, pharmaceutical and chemical industries, these industries need to obtain a specific vacuum environment. At the same time, the vacuum system used by these industries can be continuously increasing, and the vacuum degree is continuously increasing. Furthermore, the state’s environmental safety, energy saving and three wastes discharge 
to the above-stated industries, etc. Certain requirements are more stringent. At present, 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 acceleration clean vacuum environment proposed by these industries because of the restrictions of pumping acceleration 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 utilization in a clean vacuum environment with large oil-free pumping speed.