The Hunan vacuum unit is a pumping system composed of a vacuum pump and corresponding vacuum components, assembled according to performance requirements. It plays a critical role in industrial production and is widely used in various fields.

　　Based on the vacuum level they can achieve and the type of primary pump used, Hunan vacuum units can be categorized into low-vacuum pumping units, medium-vacuum pumping units, high-vacuum pumping units, ultra-high-vacuum pumping units, and oil-free vacuum pumping units. Low-vacuum pumping units are suitable for rough evacuation of vacuum chambers as well as scenarios involving large gas release rates and high working pressures, such as vacuum conveying and vacuum impregnation. Their primary pumps commonly include reciprocating vacuum pumps and oil-sealed mechanical pumps—both types of direct-atmosphere vacuum pumps. Medium-vacuum pumping units are designed for systems requiring high pumping speeds and moderate vacuum levels, and they find wide application in industries such as coating machines and vacuum metallurgy. Commonly used primary pumps for these units include oil booster pumps and Roots pumps. High-vacuum pumping units operate in the molecular flow regime, featuring low working pressures, small exhaust volumes, and high pumping speeds. Their primary pumps are typically diffusion pumps or molecular pumps. Vacuum pumping units operate within a specific vacuum pressure range and place extremely high demands on both the primary pump and the unit’s components—for instance, the primary pump must achieve an ultimate vacuum of at least 10⁻⁷ to 10⁻⁸ Pa and be capable of withstanding high-temperature baking.

　　The operating principle of a vacuum unit in Hunan is as follows: After the preliminary-stage pump (such as a vacuum pump) has evacuated the sealed chamber to a certain pressure level, the main pump (such as a Roots pump) is automatically started to continue the vacuum extraction process, thereby meeting the required technical specifications. Taking a medium-vacuum pumping unit composed of a Roots pump and an oil-sealed mechanical pump as an example, the Roots pump serves as the main pump; you can choose either a standard Z-type Roots pump or a Roots pump equipped with a bypass valve. When the system has been evacuated by the preliminary-stage pump to the pressure at which the Roots pump is allowed to start, the Roots pump begins operation. If a Roots pump with a bypass valve is used, the starting pressure can be determined based on the actual conditions of the system. In environments with low levels of dust or water vapor, a liquid-ring pump can directly perform rough evacuation of the system through the Roots pump’s pump cavity. However, if the amount of dust or water vapor is relatively high, a separate bypass rough-evacuation pipeline must be provided.

　　In the field of applications, vacuum systems are used in the medical sector for radiotherapy, operating room ventilation, and other purposes, ensuring the quality and stability of medical equipment and preventing the risk of oxygen and hydrogen leaks. In the chemical industry, vacuum pumps and steam recovery systems employed in chemical reactors guarantee that the production environment meets high-purity requirements, thereby reducing gas pollution and the risk of corrosion. In the aerospace industry, these systems are utilized for instrument and pipeline testing on aircraft, as well as for inspection and test runs of aero-engines, ensuring that the systems maintain a highly evacuated state and enhancing both system performance and safety. In semiconductor manufacturing, precise vacuum control is used to remove impurities from semiconductor devices, improving product quality and performance; it is indispensable in critical processes such as etching, ion implantation, and CVD. In the photovoltaic industry, vacuum coating technology is employed during the fabrication of solar cells to create anti-reflective layers, boosting the photoelectric conversion efficiency of the cells. Additionally, during cell cutting, a highly precise vacuum environment is provided to ensure smoothness and accuracy of the cut surfaces. In the field of new materials research and development, vacuum coating technology enables fine surface treatment of materials, facilitating the creation of novel materials with specialized properties and enhancing the purity and uniformity of new material preparation.