During decarburization procedures the vacuum system must operate long time in a tough pressure range. A competent gas-cooling is essential as the extracted warm gases would otherwise overheat the filter and vacuum system.
With the development of technology and the improvement of product quality in aerospace, energy, iron and steel digesting, pharmaceutical and chemical industries, these industries have to obtain a particular vacuum environment. At the same time, the vacuum system used by these industries is definitely continuously increasing, and the vacuum degree is 
continuously increasing. Moreover, the state’s environmental safety, energy saving and three wastes discharge to the Gas-Cooling Roots Pump above-pointed out industries, etc. Certain requirements are more stringent. At the moment, the existing dry vacuum pumps out there, such as for example screw vacuum pumps and claw vacuum pumps, are unable to meet up with the requirements of oil-free large pumping swiftness clean vacuum environment proposed by these industries due to the restrictions of pumping acceleration characteristics and structural mechanism.
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 fulfill the use in a clean vacuum environment with huge oil-free pumping speed.