Air filters are of great importance in the operation of the ventilation system. Their main task is to purify the air entering the room and protect the elements of the ventilation system from contamination, and in some cases to purify the exhaust air at the outlet of the system to the outside. Thus, not only the purity of the air that a person breathes in the room depends on them, but also the efficiency of the ventilation system as a whole, as well as the quality of the air entering the environment from the room.

Air filters in ventilation Air filters in ventilation Air filters in ventilation

The European classification of air filters for ventilation systems proposes to divide them into three groups:

  • coarse filters;

  • fine filters;

  • extra fine filters.

This classification is based on the size of dust particles captured by the filter. Coarse filters cope with dust particles as small as 10 µm, fine filters effectively trap particles larger than 1 µm inclusive, fine cleaning means the ability to cope with fine particles starting from 0.1 µm.

In turn, in each group of filters, several classes are distinguished, depending on the degree of efficiency. In Russian practice, it is customary to use EN779 and EN 1882 standards, according to these standards, filter cleaning classes are denoted by the letter G, F, EU and a number from 1 to 14. Classes G (1-4) correspond to the first type and provide air filtration from large particles . Classes F (5-9) are included in the group of fine filters. Ultrafine filters are identified by a combination of the letters EU and numbers from 10 to 14. The American and European filter classification systems use a combination of the characters EU and numbers from 1 to 14 as a letter designation.

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Coarse filters

Different levels of purification are achieved primarily due to the filter material used in the manufacture of the filter. For coarse filters, metallized meshes and synthetic fabrics may be sufficient. Such filters are usually made in the form of cellular flat, pleated, pocket filters (FyaP, FyaG, FyaK).

The scope of coarse filters depends on the class. So, class G1 (EU1) filters can be installed when low requirements are applied to air purity. Filters G2-G4 (EU2-EU4) filter the air in rooms with normal requirements. Their use is justified when the dust content of the air exceeds the maximum permissible concentration. In addition, these filters protect equipment (compressors, heat exchangers, irrigation chambers, etc.) and automation devices from dust. Coarse filters are often the first stages in an air filtration system, in which case fine filters are installed after them.

Fine filters

Fine air purification is carried out through the use of fiberglass, sometimes with special impregnation. Fine filters may also contain activated carbon inserts. Such filters are needed when it is necessary to clean the air from unpleasant odors, vapors of toxic substances. Fine filters have a different design. The most common are flat, pocket and pleated filters. Filters with activated carbon inserts are designed as pocket, pleated, cartridge filters. The scope of fine filters (cleaning class G5-G9 / EU5-EU9) is the same as for coarse filters. Their use allows you to effectively protect the air in the place of intake when it is very dusty. Fine filters allow for higher purification, they are used to combat fine dust deposits (this is especially true in museums, depositories, archives, etc.). Filters of class G8 and G9 (EU8, EU9) have the maximum level of efficiency; they are installed in food industry enterprises, in the production of medicines, in inpatient and outpatient departments of hospitals, laboratories, etc.

Extra fine filters

Filters with ultra-fine cleaning properties are made of glued fiberglass, glued submicron paper, and may have a hydrophobic coating. Their design is dry cell panel or pleated filters.

Extra fine filters are used in systems with high air quality requirements. Filters of this group are installed in medical facilities with special requirements for cleanliness: operating rooms, laboratories, in the nuclear industry, in electronic and optical industries, etc.

Extra fine filters are not installed as the only purification stage. In front of them, coarse and fine filters must be installed in the system.


Air filters in ventilation

Regardless of the purpose and class of cleaning, filters in the bulk have a similar design. They consist of a body and a removable cassette. The filter box is mounted in the ventilation system, and replaceable filter cassettes, if contaminated, must be replaced. To make changing the filter cassettes easy, there is a snap-on cover in the housing. For easy installation, filters installed in circular duct systems are usually made with round branch pipes, the size of which is equal to the connecting diameter of the duct. Rectangular filters have an inlet that is equal to the size of the cross section of a rectangular duct.

In most cases, galvanized steel is used as the material for the manufacture of the filter housing and the frame of removable cassettes, but other metals can be used.

The article was provided by the specialists of the Bastion Ventilation Plant.

Source: TopClimat.ru


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