During decarburization procedures the vacuum system must operate very long time in a tough pressure range. An efficient gas-cooling is essential as the extracted sizzling 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 processing, pharmaceutical and chemical industries, these industries have to obtain a certain vacuum environment. At the same time, the vacuum system used by these industries is certainly continuously raising, and the vacuum degree is continuously increasing. Moreover, the state’s environmental safety, energy conservation and three wastes discharge to the above-talked about industries, etc. Certain requirements are more stringent. At the moment, the prevailing dry vacuum pumps out there, such as screw vacuum pumps and claw vacuum pumps, are unable to meet up with the requirements of oil-totally free large pumping velocity clean vacuum environment proposed by these industries due to the restrictions of pumping 
acceleration characteristics and structural mechanism.
In view of the Gas-Cooling Roots Pump shortcomings of the prevailing technology, the specialized problem to be solved by the utility model is to supply an all-gas-cooled vacuum system to fulfill the use in a clean vacuum environment with large oil-free pumping speed.