Classification of Ventilation Filters

Contents:

1. Classification of ventilation filters;
2. Types of filters by filtration quality;
3. Types of filters by design;
4. Types of filters by material;
5. Types of air filters;
6. Mechanical;
7. Carbon;
8. HEPA and ULPA;
9. Electrostatic;
10. Photocatalytic;
11. Choosing a filter for different rooms.

A ventilation filter purifies the air entering a room from outside. Without a filter, harmful impurities enter the room from outside, including car exhaust fumes, factory emissions, fine dirt particles, and allergens Ventilation filters retain harmful substances and affect the final air quality in a building. Classification of Ventilation Filters

In ventilation and air conditioning systems, filters purify incoming air and, in some cases, air coming from outside the building (hazardous industries). Airborne substances and microorganisms can accumulate in the filter and negatively impact human health.

Dust, dirt particles, and pollen from flowering plants.

• Volatile compounds and aerosols harmful to human health.
• Mold particles, viral pathogens, and pathogenic microorganisms.
• Carbon dioxide, carbon monoxide, soot, and coal dust.
• Some of these substances (dust, soot, and microorganisms) settle from the air onto the surfaces of indoor objects, leading to the growth of pathogenic microflora. Therefore, air purification must be continuous and high-quality.

Filter Types by Purification Quality

When choosing a filter, it is important to know exactly what substances you want to purify the air with. The size of the particles settling in the filter is important (in the case of photocatalytic filters, dirt does not accumulate, but is broken down through a physical and chemical reaction). Depending on the percentage of purification efficiency and the size of the particles settling, ventilation filters are classified into the following classes:

Coarse filtration: efficiency greater than 40%, minimum particle size from 10 microns, filtration classes G1-G4.

• Fine filtration: efficiency from 65%, particle size from 1 micron, filtration classes F5-F9.
• Efficient filtration: efficiency from 85%, particle size from 0. 3 microns, filtration classes H10-H14.
• Ultra-efficient cleaning – 99% efficiency, particle size from 0. 1 microns, filtration classes U15-U17.
• Coarse cleaning Suitable when it is sufficient to remove dust from the incoming air. Fine cleaning More fine cleaning is possible. To reduce the cost of replacing filter elements, experts recommend installing a coarse filter first, and then a fine filter. This gives the best results at minimal cost, especially when there is a lot of dust and dirt in the outside air. Effective and ultra-efficient filtration is essential to ensure a sterile indoor environment.

Types of filters by design

Depending on the design features, the following classes of ventilation filters are distinguished:

Panels. The filter material is fixed in a housing made of steel panels. To replace the filter material, the jammed element is removed from the U-shaped frame, and a new element is inserted in its place. These filters are installed as the first stage of cleaning.

• Pockets. The filter fabric inside the frame forms a pocket in which air is finely filtered.
• Cassettes. The filter cloth is located in a cassette on a support grid. The cassette filter is used as the second stage of cleaning the supply ventilation openings.
• Filter bags. They are complex structures consisting of several modules and are often installed for ultra-fine air purification in enterprises and industry.
• Types of filters by material

The classification of ventilation filters by material determines the detail and scope of application. Each material has its own unique characteristics, including efficiency, service life and installation nuances. Therefore, before choosing a filter, you must first determine which material is best suited to the technical conditions for servicing a particular facility. Filter materials used in modern filters:

Metal mesh – the method of creating the mesh and the size of the cells vary.

• Non-metallic gratings are similar in design to metal gratings. Nylon, lavusan and polypropylene are used as materials for the production of non-metallic meshes. The main advantage over metal analogues is corrosion resistance.
• Filter fabrics – asbestos, flax and cotton flax.
• Nonwoven materials made from chemical fibers.
• Paper or cardboard.
• Types of air filters

Below is a brief overview of ventilation filter cleaning classes by type. This classification helps to understand the differences between mechanical cleaning, chemical adsorbents, electrostatic cleaning and photocatalysis.

Mechanical

This type of filter removes larger particles from the primary air such as dust, dirt, pollen and other pollutants. The filter element of a mechanical filter is a mesh made of metal, polymer material or cellulose. Depending on the mesh material, mechanical filters can be disposable or reusable.

Disposable filters should be thrown away after most of the mesh cells are clogged with dirt particles. Reusable cassettes can be cleaned (wash by hand with water and detergent) and reused for their intended purpose.

Coal

They are designed to remove aerosol particles from the air and eliminate odors. The carbon adsorbent retains high molecular weight gas molecules well. The quality of cleaning depends on the area of ​​the filter element and the number of micropores in the carbon adsorbent.

To capture low molecular weight gases, compounds are added to the filter element that bind molecules of lighter gases (aluminum and potassium compounds). Carbon adsorbents should be used in combination with mechanical filters. Otherwise, large dirt particles will quickly clog the micropores, and the degree of cleaning from the aerosol will quickly decrease.

It is undesirable to use carbon products in damp rooms, since water molecules also damage the filter elements. To effectively use carbon filtration in conditions of high humidity, a chemical adsorbent is added, which retains water molecules in the air.

HEPA and ULPA

HEPA filters for ventilation are very popular. Paper impregnated with a disinfectant composition acts as a filter material. The paper adsorbent completely prevents the penetration of solid particles into the room. Germicidal protection prevents the accumulation and growth of pathogenic microorganisms in the product. The filter element is protected from mechanical damage by a durable plastic housing. The filter element can be made of synthetic material instead of paper. This reduces the cost of the product. HEPA filters with paper cassettes provide better cleaning.

Ultrafine air purification filters ULPA are used when it is necessary to provide a sterile environment in accordance with GOST R

51251-99.The minimum particle size retained by a ULPA filter element is 0. 12 microns. The operating principle is based on mechanical air purification. Dust particles adhere to the filter fibers, and thanks to the special design of the filter material, the quality of cleaning improves over time. ULPA filters are installed in thin-layer cabinets, filter cells, ventilation ducts and filter ventilation modules.Electrostatic

Electrostatic filters are suitable for purifying air at industrial facilities from oil mist, non-metallic particles, soot and soot. The particle size deposited by the filter material is up to 0. 01 microns. This type of filter is not suitable for removing aerosols from the air.

To ensure gas removal, a different type of filter element must be added to the ventilation system. The air passing through the electrostatic filter must not contain explosive substances. Air purity when using an electrostatic device is approximately 95%. This allows the purified indoor air to be reused.

Photocatalytic

The main disadvantage of conventional filters, which allow dust particles and other filtered substances to accumulate inside, is that the device must be cleaned and the filter material replaced regularly. FCO filters (photocatalysts) do not accumulate and break down dust, dirt and other filtered substances.

FCO filters are special porous glass coated with titanium dioxide, a thin layer of catalyst. This substance reliably decomposes organic substances into water and carbon dioxide in the presence of ultraviolet light (its presence is a necessary condition for photocatalysis). Dirt accumulates in the micropores of glass and, in the presence of titanium dioxide, breaks down into water vapor and carbon dioxide. Another advantage of the FKO ventilation element is its low energy consumption. The performance of pumps equipped with filters is significantly lower than that of models with other types of filters.

Selecting a filter for different rooms

When searching for the right filter or combination of filters to ensure adequate supply air purity, several factors must be considered

What is the room used for? Air filtration systems in hospital rooms are different from those used to ventilate factory rooms.

• The type of contaminants that need to be removed from the air.
• Amount of purified air.
• The environmental conditions in which the air is generated.
• Ventilation system configuration.
• In most cases, a combination of several filters is used. For example, a mechanical filter and a carbon filter are installed in one system unit. This ensures that the potential of each product is optimally used and the required degree of purification is achieved. To determine the type of filter suitable for a particular case, it is recommended to use a classification based on the degree of air purification

Class G3-G4 – rough air purification from dust during the operation of compressors, refrigeration units, machine tools and other industrial equipment. Suitable for installation in ventilation systems in installations where there are no special hygienic requirements for air purity.

• Classes F5-F9 – fine cleaning from dust and aerosol contaminants. Filters of this class are installed in combination with coarse filters to ensure a high level of air purity. Suitable for educational institutions, hospitals, office buildings, sanatoriums and other facilities with special hygienic requirements.
• Ultra-fine purification (in accordance with European standards EU10-EU14) – air purification efficiency of 99. 99%. Used to ensure sterility in surgical departments, operating rooms, pharmaceutical production and scientific laboratories.
• The cost of equipment also influences the choice, since when designing a microclimate system it is necessary to be guided by cost optimization. The cost of installing and operating the filter can be divided into several items

The cost of the filter itself.

• Installation features.
• The need to update filter elements.
• Electricity costs.
• All these parameters should also be taken into account before purchasing and installing any type of filter for supply and exhaust ventilation.

Classification of filters for ventilation