Air filtration and purification systems

Photo: Legion-Media

Clean air is an integral part of a comfortable life. Our mood, well-being, and ultimately health depend on its quality. Even if we do not take into account extreme cases, such as fires in the summer of 2010, due to which there was suffocating smog in many regions of Russia, air pollution can cause serious respiratory diseases, respiratory diseases, allergic reactions and a number of other ailments.

Air filtration and purification systems

All contaminants can be divided according to such criteria as the type (aggregate state) of the carrier (dust, that is, small solid particles, aerosols or gaseous chemical compounds), the degree of harm to health (or hazard class according to GOST), the method of removal (using mechanical, chemical filters, by ventilation, etc.).

Most pollution is of anthropogenic origin, but there are also natural ones. Due to poor sanitation in many cities, residential air almost certainly needs to be cleaned.

What are the filters?

Household ventilation and air purification systems can be equipped with filters of various designs. The following types of devices are most widely used.

Air filtration and purification systems

Mechanical filters made of fibrous or porous materials. According to the degree of filtering ability, they are divided into coarse cleaning devices (for particles with a diameter of more than 10 microns), fine cleaning (particles of 1-10 microns), as well as HEPA (High Efficiency Particulate Air), guaranteeing the maximum level of filtration. HEPA filters are divided into five classes — from 10 (low) to 14. The higher the class, the better the quality of air purification. Modern HEPA filters of classes 13 and 14 provide a quality of cleaning suitable for cleanrooms or, say, an operating room in a hospital.

In everyday life, systems with HEPA filters of classes 11 and 12 are more common — usually this is quite enough.

Air filtration and purification systems

Photo: 3darcastudio/Fotolia.com

Electrostatic filters are charged metal plates between which air flows. The solid particles in it are electrified and attracted to the oppositely charged plate. Electrostatic devices work well with even the smallest particles, but in general they are less effective than HEPA filters.

Carbon filters are capable of retaining individual molecules of substances. They also differ in the minimum size of transmitted particles, which is no longer measured in microns, but (relatively speaking) in atomic mass units. Carbon filters do not pass particles weighing from several tens or hundreds of atomic units. Therefore, such devices cope well with aromatic hydrocarbons and other high-molecular compounds of organic and organoelement nature. But gases with low molecular weight, such as formaldehyde, sulfur dioxide and nitrogen dioxide, can not be retained by carbon filters.

Air washers are used in devices of the same name, which are used for cleaning and humidification. The principle of their operation is simple: room air is drawn into the device and passes through a plate drum rotating in the water. At the same time, the latter is capable of retaining the smallest solid particles with a size of 10 microns, including pathogenic bacteria and viruses. The advantage of air washers is that they do not require consumables and replaceable filters. For proper operation, it is enough to periodically add clean water and clean the drum from lime deposits.

Air filtration and purification systems

Photo: Siegenia. Wall ventilators Aeropac (Siegenia) are comfortable and safe. In addition, they can be equipped with additional filters that prevent exhaust gases and other volatile compounds from entering the home.

An important characteristic of all filters is the ability to retain a certain amount of contaminants. For example, in various modifications, 1 g of carbon filter material can capture from 30–50 to 200 mg of substances. The dust capacity of mechanical and electrostatic filters also varies depending on the model. Accordingly, the service life of filters varies significantly. After it expires, the device must be replaced (if it is disposable) or cleaned according to the instructions. Unfortunately, in household systems, there are almost no mechanisms for precise control over the condition of the filter (for example, estimating the air pressure drop on the dust-trapping layer), so you have to focus on the date of installation and the estimated service life of the product. In such cases, it is better to play it safe and change another serviceable filter.

When choosing ventilation units, give preference to models with a filter that ensures the proper quality of the air entering the premises.

Some reusable filters do not lose their properties after cleaning (washing). This is the case, for example, with electrostatic or grease-catching devices (the latter are used in kitchen hoods and are made in the form of a fine metal mesh). But the dust-collecting properties of filters made of fibrous and porous materials usually deteriorate after washing, so it is not recommended to use them for more than three or four cleaning cycles. At the same time, after each subsequent replacement, the service life decreases (data on the number of cycles and the reduction in service life should be checked with manufacturers).

Charcoal filters are sometimes also beyond repair. They cannot be washed, moreover, they are very susceptible to atmospheric moisture: the higher the humidity of the air, the shorter their service life. However, there are also washable models. In any case, when choosing a filter, you need to find out exactly how it should be maintained, whether it needs to be washed or needs to be replaced.

Air filtration and purification systems

Photo: Venta. Air purifier-humidifier Venta LW45 for rooms up to 75 m2. The contact area of ​​the drum plates in the LW45 model is 4.2 m2, and the capacity is 270 m3/h

Along with the devices described above, air ionizers are used in filtration systems. They are, for example, in a number of models of air conditioners from LG, Mitsubishi, Samsung, Panasonic and other manufacturers. The ions created by these devices affect bacteria and microorganisms (destroy their shells), odor and tobacco smoke molecules (break them down), as well as submicroparticles that are deposited on oppositely charged electrodes. Thus, the ionizer can be considered an additional superfine filter.

When using air conditioning systems, it is also necessary to use mechanisms to protect against microbiological air pollution. For example, LG air conditioners have an Auto Cleaning function that helps prevent mold and bacteria in the cavities of the indoor unit’s heat exchanger. Residual moisture is automatically removed after the end of cooling operation, which is facilitated by the rotation of the fan at ultra-low speed and the drying of the surface of the heat exchanger. In addition, the ion sterilization function is activated, which allows you to remove the remaining microbes and mold, which completely disinfects the cavity of the indoor unit and eliminates unpleasant odors.

How to get rid of dust

Speaking of air pollution, many will first of all remember dust with an unkind word. These solid particles (with a diameter of tenths
up to a few microns) are easily carried by air currents, and the smallest of them (several microns in diameter) can float
in air currents for almost unlimited time. A certain amount of dust is formed inside the dwelling, but most of it is of natural (the result of weathering or volcanic emissions) and even alien origin, so the problem cannot always be solved by simply replacing “home” air with outdoor air. Especially if it’s dry and windy outside. Dust concentration is greatly reduced in humid air, which is why ventilation is most effective during or immediately after rain.

We build multi-level protection

How do you know what pollutants are in the air? The miner’s method «with a canary» is not suitable here, it is much more efficient to conduct laboratory air tests. A standard chemical study will cost about 8–10 thousand rubles. It usually includes analysis for external pollutants caused by industrial enterprises and vehicles (CH₄, CO, sulfur oxides, nitrogen oxides); analysis for internal pollutants from furniture, finishing materials and household chemicals (phenol, formaldehyde, ammonia); determination of gas indicators (СО₂ and О₂). In addition, the composition and concentration of dust in the air are established. Advanced chemical analysis costs twice as much, but the list of pollutants for which tests are carried out is much wider. In addition to the substances present in the standard analysis, hydrogen sulfide, benzene, xylenes, styrene, toluene, etc. are also detected. A microbiological study is carried out separately, which costs about 5–6 thousand rubles. It includes an analysis of the total microbial count of opportunistic, pathogenic bacteria and mold fungi, determination of the total number of microbes, as well as an analysis for the presence of Legionella pneumophillia bacillus. The price always depends on the area of ​​​​the room and the number of samples. If there are industrial enterprises nearby, whose activities are of concern, it is recommended to analyze the pollution emitted by them, and then analyze the air, taking into account the substances characteristic of these factories and plants.

Due to improper care, even cleaning filters can become a source of dangerous biological contaminants, so the condition of the devices must be monitored and consumables replaced in a timely manner.

After clarifying the main sources of pollution, you can proceed to the arrangement of air purification systems. For local cleaning of dust and some gaseous pollutants, portable or stationary devices are used, usually equipped with coarse and fine mechanical filters, as well as a carbon filter. Portable air purifiers, humidifiers, air washers, kitchen hoods, etc. are very popular. Multi-level filtration systems (the number of levels usually corresponds to the number of filters) are usually equipped with air conditioners — both portable and stationary.

Ways to deal with pollution

  1. Maintaining the necessary microclimate parameters (temperature and humidity) in the home.
  2. Systematic ventilation of premises.
  3. Regular and thorough wet cleaning.
  4. The use of environmentally friendly building materials and furniture.
  5. Use of humidifiers and air purifiers, as well as stationary ventilation systems.

In addition, to effectively combat air pollution in the house, it is necessary to block all sources of microbes, dust, etc. Most likely, it will be necessary to clean not only the air circulating inside the room, but also coming from outside. Forced supply and exhaust ventilation systems should be equipped with filters, and the latter should be placed in such a way that, if necessary, they can be easily changed or cleaned. The same can be said about the indoor units of air conditioners: they must be available to replace filter consumables.

Air filtration and purification systems

Photo: Rusklimat. The split system Ballu BSA-09HN1 of the i Green series is equipped with a high-density air filter Green- and a three-component filtration system Combo 3 (Catechin / Vitamin C / Coal)

It is desirable that local cleaning devices be equipped with a system that automatically responds to air pollution. Such automation can be installed in kitchen hoods (most often luxury) and some models of portable air purifiers.

What types of air pollution are typical for various buildings — new buildings, old houses (secondary housing stock), country cottages, as well as for basements? new buildings are characterized by chemical and microbiological air pollution associated with the repair and construction work carried out. Microbiological contamination can be caused by dampness of the building during the construction process, that is, it was heated in the autumn-winter period. In the buildings of the old building, microbiological air pollution is mainly found, due to the long use of the housing stock and poor-quality cleaning of the premises. Mold (microbiological contamination) appears in the basements due to high humidity, and on the first floors of buildings (occasionally) — natural radioactive gas radon. For country houses, all of the above can be characteristic. You should also pay attention to building materials and furniture — they are often the source of formaldehyde and phenol. After the repair and purchase of furniture, it is advisable to intensively ventilate the room for a week; if the smell is not eliminated, then there is cause for concern.

Nikolai Ivanov

Leading Specialist Ecostandart Group

Some types of household air pollution

Type of pollution Impact Cleaning method
Solid particles with a diameter of 10 microns or more Irritant effect on the respiratory organs and the mucous membrane of the eyes, allergic reactions; dust accumulates on furniture, due to static electricity — on electronic parts, causing it to overheat Mechanical (coarse filters). electrostatic filter
Solid particles less than 10 µm in diameter Microorganisms cause various infectious and viral diseases. Fine dust can also provoke allergic reactions. Mechanical (fine filters). electrostatic filter
Aerosols Can serve as a «parachute» for microorganisms and various allergens Electrostatic, mechanical filters
High-molecular gaseous compounds (esters),
combustion gases, etc.
Poisonous, capable of causing poisoning, in small concentrations cause headaches, reduced performance, irritate the respiratory system, etc. An unpleasant odor occurs. Carbon filter. If the source of pollution is inside
rooms — ventilation
Low molecular weight gases (carbon monoxide, i.e. carbon monoxide, phenol, formaldehyde) Causes life-threatening poisoning at high concentrations Airing; elimination of sources (for example, malfunctions of heating devices when carbon monoxide appears)
Radon Radioactive gas hazardous to health Only airing
Low oxygen concentration Decreased performance, headache Only airing

  • Source: Ideas for Your Home Magazine#204


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