Air cleaners are made in the form of floor (desktop) and suspended devices. Some models specifically designed for ceiling mounting are mainly designed to neutralize volatile pollutants such as tobacco smoke. They don’t do well with house dust.
A typical air cleaner consists of fan and set filters on which particles of air pollutants settle. In modern models of air purifiers, there may be several fan speeds. The more speeds, the more opportunities for flexible performance regulation in case of «force majeure situations» like a sudden visit of guests — inveterate smokers. And in the most modern Japanese air cleaners, inverter technology is used, which allows you to smoothly change the fan speed from minimum to maximum. It should be borne in mind that most air purifiers are designed to operate continuously at minimum power, since it is in this case that the noise level produced by them will be minimal.
For ease of use, some models of cleaners are equipped with an infrared remote control . This is especially convenient for those rooms in which it is necessary to change the air purification mode frequently. If the purifier works constantly with the same load, under constant conditions, then there is no particular need for a remote control. Also, for convenience, some cleaners use indicators power mode, dustiness, noise level, the need to clean or replace filters.
Usually, for higher air purification, several types of filters are included in the air cleaner, assembled in a single housing. Currently, the following types of filters are used in household air cleaners:
Prefilters (mechanical filters)
Electrostatic (ionizing) filters
HEPA filters (fine mechanical filters)
Carbon (adsorption) filters
Air purifiers: all models
Prefilters (mechanical filters) — the simplest filters used in air cleaners. They consist of the usual fine mesh and are designed to remove large dust particles, animal hair. Such filters are installed on almost all climatic equipment and protect not only people, but also the insides of the devices themselves from dust. Preliminary mesh filters are reusable — to clean them from dust, it is enough to vacuum or rinse in warm water.
Fine air filters — HEPA ( H igh E fficiency P articulate A rresting is the main filter element in many air cleaners. HEPA filters were originally developed for the equipment of ventilation systems in medical institutions and premises with increased requirements for air purity; the technology is widespread in the West, used in industrial and domestic air cleaners.
The principle of operation of HEPA filters is quite simple: the air is driven through the filter by a fan and thereby freed from dust particles. The HEPA filter traps more than 99% of all particles with a size of 0.3 microns or more, including pollen, fungal spores, animal hair and dander, house dust mite allergens, etc. Therefore, HEPA filters are used in vacuum cleaners or air purifiers that recommended for people with allergies. But the surface of the filters represents a very convenient «bridgehead» for microorganisms, so manufacturers additionally impregnate them with a special chemical composition that inhibits the vital activity of bacteria (be sure to ask if such impregnation is provided for in the filter you have chosen).
The HEPA filter is a replaceable element that requires cleaning and replacement as it gets dirty, its validity period (from 6 months to 5 years) is highly dependent on the degree of environmental pollution.
Operating principle electrostatic filters , is based on the attraction of electric charges of different polarity. Polluted air passes through the ionization chamber, in which the pollutant particles acquire a positive charge, after which they settle on negatively charged plates. To clean such a filter (plates), it is enough to wash it with soapy water. Electrostatic filters well clean the air from dust and soot. With this method, it is possible to achieve filtration efficiency that meets and even exceeds the known HEPA standard. Air cleaners equipped with these electrostatic filters are often combined with HEPA, carbon filters.
main purpose carbon filters — absorption of odors. Activated charcoal physically absorbs the odor-causing gas molecules into its pores. However, these filters are not very effective when used in a high humidity environment. Also, activated carbon is not effective in removing low molecular weight gases such as formaldehyde, sulfur dioxide, and nitrogen dioxide. Therefore, in air cleaners it is used in combination with other filters (HEPA, electrostatic, photocatalytic filters).
It is important that, in addition to carbon filters, air cleaners are equipped with mechanical filters (preliminary cleaning — dust absorbing). If the pre-filter does not effectively retain particulates, they will accumulate in the micropores of the carbon filter, which will lead to premature wear.
It is mandatory to change the carbon filter every 4-6 months, because as toxins and dust accumulate, the filter itself can become a source of pollution (at some point, “throw away” some of the accumulated over several months).
Photocatalytic filters — a novelty in the field of air purification, they are considered one of the best to date. The essence of the air purification method is the decomposition and oxidation of toxic impurities on the surface of the photocatalyst under the action of ultraviolet radiation. The reactions proceed at room temperature, while organic impurities do not accumulate, but are destroyed to harmless components (water and carbon dioxide), and photocatalytic oxidation is equally effective against toxins, viruses or bacteria — the result is the same. Most odors are caused by organic compounds, which are also completely decomposed by the photocatalytic filter.