HEPA is a high-efficiency air filter. According to the single filtration rate calculation, standard HEPA filters can filter particles as small as 0.3 microns in the air, with a filtration rate of at least 99.97%. They are widely used in hospitals, laboratories, and precision instrument production workshops with strict air quality requirements.
Single filtration rate refers to the determination of the filtration capacity of a filter by comparing the changes in the number of air particles during a single process from the intake of air to the discharge of fresh air.
HEPA filter grade
According to the EU EN1882 standard, HEPAl filters are classified into 5 levels based on their filtration efficiency: coarse filter, medium filter, sub high efficiency filter, HEPA high efficiency filter, and ultra high efficiency filter. A filter with a filtration efficiency higher than 99.9% for particles with a diameter of 0.3 μ m is called H12.
The national standard requires HEPA materials to have a filtration efficiency of F9 or higher. But as the level increases, the purification ability becomes stronger, and the wind resistance will also increase. Therefore, under the same conditions, air purifiers with higher HEPA levels tend to have lower CADR values.
Why does it have a sour taste?
Actually, this is a problem that most filtering air purifiers have. Because air purifiers adsorb particles and microorganisms in the air onto the filter screen during operation, under appropriate temperature and humidity conditions, the filter screen will breed bacteria and produce odors. In addition, the activated carbon filter in air purifiers can also produce a sour taste when exposed to moisture.
In response to this situation, the editor of Shiyang Electromechanical suggests taking out the filter element and placing it in a sunny and ventilated place to dry, as the "sour taste" may become lighter. If it doesn't work, we suggest you replace the filter directly.
Why can't HEPA filters be washed with water?
Replacing the filter element is the most direct method, but some friends are concerned that the cost of replacing the filter element once is too high. Indeed, the price of HEPA filters in air purifiers ranges from 200 to 1000 yuan. There are many materials that make up HEPA filters, including PP (polypropylene) high-efficiency filter paper, PET filter paper, PP and PET composite high-efficiency filter paper, and fiberglass high-efficiency filter paper. PP (polypropylene) is a type of paper, so it generally cannot be washed with water. The other part of the HEPA filter is made of PET or PTFE material, which is the origin of many claims online that water washed HEPA filters are used. However, the efficiency of this type of HEPA filter is very low and is not recommended for use.
