With the continuous development of economy and the improvement of people's living standards, people have higher and higher requirements for product quality. This puts forward higher requirements for production technology and production environment, so the level of clean environment directly determines the level of product quality and efficiency. Especially in the fields of electronics, pharmacy, food, bioengineering, medical treatment, laboratory and so on, there are strict requirements for the cleanliness of production environment. Therefore, different customers have different requirements for the design and use of clean Engineering, and their clean environment grades are also different. There will be different levels of design requirements, such as level 10, level 100, level 1000, level 10000, level 10000, level 100000, level 300000 air purification system engineering.

In order to meet the actual needs of the enterprise, according to the combination of design and actual use of many advanced clean rooms in China at present, starting from the initial investment of investors and other factors, to the actual clean environment required by the enterprise, and reasonable control from various technical indicators of the production environment, to meet the requirements of special production process. Especially in recent years, the propaganda of national policies on environmental protection and energy conservation has been deeply rooted in the hearts of the people. Many large and medium-sized cities' requirements and restrictions on investors mainly show the direction of energy conservation, environmental protection and sustainable development. And these are the research and development direction of fresh purification in the field of clean engineering.