With the development of vacuum application, there are more and more kinds of vacuum pumps, and their pumping speed ranges from tens of liters per second to hundreds of thousands and millions of liters per second. With the increasing demand for the application pressure range of vacuum technology in the fields of production and scientific research, most of them need a vacuum pumping system composed of several vacuum pumps to pump air together to meet the requirements of production and scientific research. Because the vacuum application department involves a wide range of working pressures, any type of vacuum pump can not be completely suitable for all working pressure ranges, and different types of vacuum pumps can only be used according to different working pressure ranges and different working requirements. In order to be convenient to use and meet the needs of various vacuum processes, various vacuum pumps are sometimes combined according to their performance requirements and applied in the form of units.

Commonly used vacuum pumps include dry screw vacuum pump, water ring pump, reciprocating pump, slide valve pump, rotary vane pump, Roots pump and diffusion pump. These pumps are essential main pumps for the application of vacuum technology in various industries of our national economy. In recent years, with the sustained and high-speed economic development in China, the downstream application industries related to vacuum pumps have maintained a rapid growth momentum. At the same time, driven by the continuous expansion of vacuum pump application fields and other factors, China's vacuum pump industry has achieved sustained, stable and rapid development.