The HEPA standard is set in the United States: for dust of 0.3 micrometers and above, it is required that the filtering efficiency of such dust should reach 99.97% or above.
How are the grades of HEPA filters divided?
Generally, HEPA is divided into five levels according to its filtration efficiency: coarse efficiency filter, medium efficiency filter, sub efficiency filter, HEPA efficiency filter, and ultra efficiency filter.
Common grade standards for HEPA filter screens:
HEPA filters are subdivided into H10-H14 and U15-U17 according to current European grades. The common type of HEPA in air purifiers is Grade H, which belongs to high-efficiency or sub high-efficiency filter screens. The H13 HEPA filter can achieve a total efficiency of 99.95%. The total efficiency of the H14 HEPA filter can reach 99.995%. Of course, in European standards, the high purification level of HEPA filters is Grade U, and the total purification efficiency of Grade U17 HEPA filters can even reach 99.99987%. However, due to the high production cost of U-grade HEPA filters, and the strict requirements for the production environment. So there are not many applications in the market.
HEPA is a high efficiency air filter. Based on the single filtration rate, the standard HEPA filter can filter particles ranging from small to 0.3 microns in the air, with a filtration rate of at least 99.97%. It is widely used in hospitals, laboratories, precision instrument production workshops, and other places with strict air quality requirements. HEPA filters can be roughly divided into three levels: high, medium, and low. Each level has its own advantages and disadvantages. First of all, taking H13 and above as an example, high-grade HEPA filters can efficiently filter out more than 99% of particulate pollutants, but at the same time, they often increase the wind resistance of the air purifier, which directly reduces the purification efficiency and outweighs the losses. Secondly, medium and low grade HEPA filters, although they can maintain a stable wind force, affect the filtering effect of particles below PM2.5, and the two cannot be taken into account. Even if both can be taken into account, this increases power consumption and also imposes mutual constraints on performance. Therefore, no matter which grade of HEPA filter screen is available, there are drawbacks. To avoid these drawbacks, it is necessary to choose a relatively balanced and reliable comprehensive performance to be more practical.