Brief introduction to classification standard of air filter filtration grade

According to the filtering effect, air filters are strictly classified. At present, the European standards commonly used in the industry are generally divided into 17 grades from G1 to U17, and the total purification efficiency of HEPA filter screen with the highest grade of U17 can even reach 99.999997%.

If divided according to Chinese standards, it is generally divided into five grades: coarse efficiency, medium efficiency, high efficiency, sub efficiency and high efficiency. From the comparison of the figure below, F7-F8 in European standard is called high and medium efficiency filter screen; F9-H11 is called sub high efficiency filter screen, H12-H14 is called high efficiency filter screen, and U15~U17 are generally called super high efficiency filter screen.

In addition to the common European standards and winning bids, there is also an American standard ASHRAE that is not commonly used. American standard is divided from C1 to UH20, with a total of 20 grades. Different from the European standard, the purification effect of H13 in the American standard is roughly equal to F7 in the European standard, which belongs to the high and medium efficiency filter screen, while the UH17 in the American standard is roughly equivalent to H13 in the European standard, which is what we call the high efficiency filter screen.

Therefore, in order to ensure the best effect of air purification, we'd better select a filter screen with the filter screen level above H12 (or high efficiency) when selecting a new fan, so as to fundamentally solve the problem of PM2.5. However, in the fresh air system, the primary, medium and high efficiency filters are generally not used separately, but two or three types are used together. The primary filter screen can filter out some large particles, allowing HEPA filter screen to focus on filtering smaller particles, reducing the burden of HEPA filter screen. Therefore, the fresh air system with more than two filters can achieve better air filtering effect.