How to choose a HEPA filter in an air purifier? How often is it appropriate to change the filter?

How to choose an air purifier inHEPA filter? How often is it appropriate to change the filter?

Research has shown that viruses can spread by relying on vectors such as aerosols or particulate matter, which are gaseous dispersed systems of solid or liquid particles suspended in a gaseous medium, with particle sizes typically ranging from 0.01 to 10 μm. When aerosol concentrations reach sufficiently high levels, they will pose a threat to human health, especially to asthmatics and others with respiratory problems. Airborne aerosols are also capable of transmitting fungi and viruses, which can lead to epidemics and outbreaks of disease in some areas.

And air purifiers can remove aerosols in the air, academician Zhong Nanshan previously accepted an interview also particularly emphasized the importance of dealing with indoor air pollution, he said: "My view is that, there are conditions or you can consider air purifiers." Air purifiers are mainly composed of two parts: the cartridge and the shell, the basic requirements are high filtration efficiency, low flow resistance, can be used continuously for a longer period of time in order to reduce the cost of late supplies. The key to this is the HEPA filter or HEPA high efficiency filter.

In this, HEPA generally refers to high-efficiency air filters, HEPA filters are mainly used to capture particles above 0.5μm dust and a variety of suspended matter. According to GB/T6165-1985 "High Efficiency Air Filter Performance Test Methods Transmission Rate and Resistance" method test, its transmission rate ≤ 0.1% (i.e., efficiency ≥ 99.9%) or the counting of particles ≥ 0.1μm particle transmittance rate of ≤ 0.001% (i.e., efficiency ≥ 99.999%) of the filter for the high-efficiency air filter. Filters with a counting rate of ≤0.001% (i.e. efficiency ≥99.999%) for particles of ≥0.1μm are considered high efficiency air filters.

More commonly used in air purifiers on the market today are HEPA high-efficiency filters, which are filters that meet the HEPA standard.HEPA mesh is characterized by the fact that air can pass through it, but fine particles cannot. The efficiency for 0.1 micron and 0.3 micron reaches 99.7%, and the removal efficiency for particles with a diameter of 0.3 micron (1/200 of the diameter of a hair) or more can reach more than 99.97%.

Bacteria and other microorganisms are mostly within the HEPA interception range, and even smaller viruses can be effectively intercepted because their state of existence is mostly attached to airborne particles. According to the information released by the Institute for Prevention and Control of Viral Diseases of the Chinese Center for Disease Control and Prevention (CDC) on January 24, the new coronavirus has a diameter of 60-140 nanometers. The particles are round or oval in shape, similar in size to the H1N1 virus (which measures 80-120 nanometers), and both are also found in airborne aerosols or droplets.

Tested by authoritative testing organizations, MERV16 or H12 and above level and has an antimicrobial coating of high-efficiency HEPA filter air purifier, can filter out the H1N1 virus up to 99.99%. This is because the microorganisms intercepted on the surface of the HEPA are mostly due to the death of dry airflow, and at the same time, some of the air purifiers are equipped with UV lamps or plasma generators, and viruses are UV and heat-sensitive, so they can play an effective role in killing viruses. and heat sensitivity, so it can play an effective role in killing the virus.

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How often should I change the filter on my air purifier?

Air purifier filters commonly used filter materials are: nylon primary filter, PP cotton, activated carbon filter, HEPA high-efficiency filter. The main role of the coarse filter is to filter hair, and other large particles of pollutants, PP cotton; activated carbon filter is mainly used to adsorb odor, deodorization, etc.; HEPA high-efficiency filters can be filtered 0.3 micron solid particles of pollutants, aerosols, and even part of the microorganisms such as bacteria or fungi. For air purifiers, the filtration effect mainly depends on the filter's good or bad, so you need to clean or replace the filter material on a regular basis and in a timely manner. So how often is it appropriate to change it?

First of all, for the nylon coarse filter, PP cotton, most of which is washable, that is, in the use of a month or two months, or even longer, you can directly remove it, and then water hydrogen can be attached to the surface of the dust, hair and other pollutants can be cleaned up to be loaded back to use, usually the use of the period of time in a year or so need to be replaced in order to ensure that purification effect. Of course, the specific replacement time should also be based on the specific use and aging to determine the situation.

Secondly, for activated carbon filters, they can be placed in the sun for 2~4 hours to restore the adsorption function of activated carbon, and usually the use cycle of activated carbon filters is between 0.5~1 year. The main role of the activated carbon filter is to adsorb indoor odors, odors, etc., including toilet odors, kitchen odors, as well as sofas or closets and other furniture volatile formaldehyde, etc.. Activated carbon adsorption is limited, if the poor quality of the environment is very easy to reach saturation, although the air purifier work has been the formation of airflow, air circulation, activated carbon filter is often dry (except for the environment of the humid indoor air), but the indoor temperature is low to promote the activated carbon is difficult to release adsorbent (and the release of adsorbent indoors will result in the secondary pollution of the indoor air), so regular week, two weeks, three weeks! ...... and other time will be placed in the activated carbon as an open place sun exposure, is conducive to improving the adsorption of activated carbon filters, while not causing secondary pollution of the indoor air environment. Of course, if necessary, timely replacement of new activated carbon filters.

Again, for the HEPA filter, it is a fiber structure, such as mite dust, pollen, germs, second-hand smoke, dust and other small particles of the purification efficiency of 99.9% or more, and even for the 0.3 micron particles of the purification rate of more than 99.9%. purification effect is good at the same time, but also face the problem of cleaning or replacement frequency is fast, most of the current air purifier HEPA are folded layered structure, which means that its unfolding area and air contact area increases. The HEPA of most air purifiers is a folded layered structure, which means that its unfolding area and air contact area increase. In general, HEPA filters need to be cleaned regularly once a week, two weeks, three weeks ...... and the way to clean HEPA filters is usually to use vacuum cleaners, hairdryers and other tools to remove pollutants adhering to their surfaces. In general, the service life of the HEPA filter of the air purifier is between 0.5 and 1 year, and it may need to be replaced more frequently if it is often smoked indoors and affected by outdoor dust and other particles.