Classification of household air purifiers

　　Classification of household air purifiers

　　There are five internationally accepted principles of air purification, physical, electrostatic, chemical, negative ion and compound. Generally speaking, air purifiers that use multiple purification methods at the same time will have a better purification effect. For example, large particulate matter such as dust, peculiar smell, pollen, etc. can be filtered through physical purification methods; while allergens, viruses, formaldehyde and other harmful substances need to be purified by chemical purification methods. Purification methods are divided from the active direction, and there are active purification methods (air purification) and passive purification methods (fixed-point purification). The passive purification method only has a purification effect on the inhaled air; the active purification method will have a purification effect on the entire space.

　　1. Passive air purifiers mainly use fans to draw air into the machine, and then filter the air through a built-in filter, which can filter dust, odor, and disinfection. Filter-type air purifiers mostly use HEPA filter + activated carbon filter + photocatalyst (cold catalyst, how far away catalyst) + ultraviolet disinfection + electrostatic adsorption filter and other methods to process the air. The HEPA filter has the function of filtering dust particles. Activated carbon and other substances mainly absorb toxic and harmful substances such as peculiar smell. 2. The principle of active air purification is different from the principle of passive air purification in that the active air purifier gets rid of the restrictions of the fan and filter, and does not need to passively wait until the air is drawn in and then filtered and then discharged through the fan. Instead, it effectively and actively releases the purification and sterilization factors into the air, and through the characteristics of diffusion in the air, it reaches all corners of the room to purify the air without blind corner. The basic structure of an air purifier is actually not complicated. It is generally composed of a fan and an air filter. The working principle is simply that the fan in the air purifier first inhales polluted air. When passing through the air filter, the various pollutants carried will be removed or adsorbed, and then discharged through the air outlet, so as to achieve the purpose of purifying the air.

　　1. The basic index of air purifier-basic purification capacity (CADR value)

　　The basic purification capacity (CADR) size of the air purifier is the first thing to note. CADR is the English abbreviation of the clean air output ratio, and the unit is marked as "XXX cubic meters/hour". Generally, manufacturers will mention the product introduction, packaging and body.

　　The CADR value reflects the ability of the air purifier to remove dust, second-hand smoke and pollen. The higher the CADR value, the higher the purification efficiency. The CADR value can be used to evaluate the effect of air purifiers in removing indoor air pollutants after a certain period of operation. If indoor pollution sources continue to be generated, the use of air purifiers with a large CADR value can keep indoor pollutants at a lower concentration.

　　Internationally recognized standards generally require that when the air purifier is working, the number of air cycles in the room should not be less than 5 times per hour. To put it simply, a room of 30 square meters should be calculated with an air purifier with a CADR value of 400 cubic meters per hour, while for 20 square meters, choose a CADR value of 260 cubic meters per hour, and for a room of 15 square meters, choose a CADR value of 200 cubic meters per hour , So on and so forth.

　　2. The basic index of air purifier-noise value

　　As for household appliances that may need to run for a long time, the noise level of the working time of the air purifier also requires special attention. Take the hearing of ordinary people as an example. 20 to 40 decibels (dB) is like whispering and relatively quiet, 40 to 60 decibels (dB) is equivalent to ordinary indoor conversation, and 60 decibels (dB) or more belong to the category of noisy , Being in the noise for a long time will affect people's physical and mental health. In the case of air purifiers with different air volume settings, the magnitude of the operating sound is different. Generally, manufacturers will indicate the range of their working noise value in the product introduction, and the unit is marked as "XXdB to XXdB".

　　3. The basic index of air purifier-air filter

　　As the most important part of the air purifier, the air filter must also be carefully selected before purchasing. Because the pollutants in the indoor air mainly include bacteria, viruses, dust, pollen, mold spores, odor and harmful chemical gases, etc., and several common air filter technologies have different effects in response to different pollution situations. .

　　At present, the most commonly used technology in air filters is physical filtration through HEPA (High Efficiency Particulate Air Filter). HEPA is usually composed of chemical fiber or glass fiber material, and the common HEPA filter is composed of multiple layers of folded fiber membranes. The area after unfolding is equivalent to dozens of times when folded. HEPA has a filtration efficiency of more than 99.97% for particles with a diameter of 0.3 microns (PM0.3) or more. It is the most effective filter medium for pollutants such as smoke, dust particles, and bacteria. Moreover, HEPA is relatively mature and is recognized as the best high-efficiency filter material in the world, so it is widely adopted by mainstream brands of air purifiers. But HEPA is powerless against harmful chemical gases, and it also needs to be replaced and maintained regularly during use.

　　4, The basic index of air filter-activated carbon

　　Compared with the poor filtering effect of HEPA technology filters on harmful chemical gases such as benzene and formaldehyde, most brands of air purifiers also use filters based on activated carbon technology. Activated carbon filters usually have a grid structure with a grid inside. With activated carbon particles, special structure and the characteristics of activated carbon, this filter screen has the advantages of small wind resistance coefficient, large specific surface area, and strong adsorption capacity. Activated carbon is obtained from raw materials such as coal, wood and fruit shells through carbonization, activation and post-treatment. Because the carbon particles have a large surface area, they can fully contact and adsorb harmful chemical gases. However, activated carbon can only temporarily adsorb a certain amount of pollutants. When the temperature and wind speed rise to a certain level, the adsorbed pollutants may dissociate and cause secondary pollution. Therefore, it should be replaced regularly during use to avoid saturation of adsorption. In addition to the two commonly used physical filtration technologies for air purifiers, the other more mainstream technologies include electrostatic dust collection and photocatalyst technology. Among them, electrostatic dust collection technology uses high-voltage DC electric field to ionize dust-containing gas, and the dust particles and negative ions After being combined and charged with a negative charge, it will discharge and deposit on the surface of the anode, so as to achieve the purpose of filtering dust and purifying the air.

　　5, Pay attention to the replacement and maintenance of the filter

　　If the air purifier is not cleaned and maintained for a long time, and the filter is not maintained and replaced, it will not only fail to purify the air, but will become a breeding ground for bacteria, which may even endanger the health of users in severe cases. Therefore, before using the air purifier for the first time, you should choose a suitable place indoors according to actual needs. When placing the air purifier, ensure that the air purifier is placed stably, while ensuring that the air inlet and outlet are unobstructed, and then put it at room temperature for half an hour before turning it on. use. Due to the particularity of the working environment, the air purifier needs to clean the dust and dirt on the shell regularly. Generally, you can use a damp cloth to wipe it, but do not use gasoline, banana water and other organic solvents to scrub, so as not to damage the plastic shell.

　　The common first layer of filter inside an air purifier is a pre-filter shaped like a large air conditioner filter, which can pre-filter larger particles of pollutants such as hair and pet hair. However, it will accumulate a certain amount of dust when it is used for a long time, which will affect the air intake and the effect of air purification, so it needs to be cleaned in time.

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