During decarburization procedures the vacuum system needs to 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 product quality in aerospace, electric power, iron and steel digesting, pharmaceutical and chemical industries, these industries need to obtain a specific vacuum environment. Simultaneously, the vacuum system utilized by these industries is certainly continuously raising, and the 
vacuum level is continuously increasing. Furthermore, the state’s environmental security, energy saving and three wastes discharge to the above-stated industries, etc. Certain requirements are more stringent. At present, the prevailing dry vacuum pumps Gas-Cooling Roots Pump available, such as for example screw vacuum pumps and claw vacuum pumps, are unable to meet up with the requirements of oil-free large pumping velocity clean vacuum environment proposed by these industries because of the restrictions of pumping swiftness characteristics and structural mechanism.
Because 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 fulfill the utilization in a clean vacuum environment with huge oil-free pumping speed.