The rapid development of air filters is closely related to the development of military industry and electronic industry. During the First World War, due to the use of various chemicals, military gas masks with asbestos fiber filter paper as smoke filter layer came into being. Glass fiber filter media for air filtration was patented in the United States in June 1940. In 1950s, the United States deeply studied the production technology of glass fiber filter paper, and improved and developed the air filter. In 1960s, HEPA filter came out; In 1970s, the HEPA filter with micro-glass fiber filter paper as the filter medium had a filtration efficiency of 99.9998% for particles with a particle size of 0.65438 0.3 micron. Since 1980s, with the appearance of new testing methods, the improvement of use evaluation and the improvement of filtration performance requirements, it was found that there were serious problems in HEPA filter, so ULPA filter with higher performance was produced. At present, countries are still studying hard, and it is estimated that more advanced air filters will appear soon.
The design of the air filter itself has also made remarkable progress, the most important of which is to cancel the baffle, that is, to develop a non-baffle filter. The separator-free filter not only eliminates the danger that the separator damages the filter medium, but also effectively increases the filtering area, improves the filtering efficiency and reduces the airflow resistance, thus reducing the energy consumption. In addition, air filters have made great progress in high temperature resistance, corrosion resistance, waterproof and antibacterial, and met some special needs.