How Air Purifier Works?

An air purifier is an electrical appliance that many families need today. Modern residential homes are highly airtight, thermally and acoustically insulated, which is great in terms of energy efficiency, but not so good in terms of indoor air quality. Because newly built homes typically don't get as much outside air as older homes, pollutants can build up inside, including dust, pet hair, and cleaning products. The air is more polluted, which is a significant problem if you have allergies, asthma or are susceptible to respiratory irritation. How an air purifier works should be understood before purchasing one. This will help you buy the best device and place it at home.

How does an air purifier work?

An air purifier is a compact device with a large number of filters. In the house, the device not only eliminates dust and pollen flying from the street, but also allergens, animal hair particles, unpleasant odors and microorganisms. The constant use of the device significantly improves the microclimate of the room. The house becomes easier to breathe, people are less likely to suffer from respiratory diseases and allergic symptoms. So how do air purifiers actually work? 

The principle of operation of the air purifier makes it a very useful device in the home. Air purifiers usually consist of a filter or several filters and a fan that sucks in and circulates the air. When air passes through the filter, pollutants and particles are captured and clean air is pushed back into the living space. Filters are typically made of paper, fiber (often fiberglass), or mesh and require regular replacement to maintain efficiency.

Simply put, the air purifier operates on the following principle:

• Air is drawn from the room inside the unit.
• Pass through built-in filters.
• Return to the outside, either naturally or by a fan.

What types of air purifiers are there?

All air purifiers fall into different categories depending on how they function. Below we will consider what types of purifiers there are.

• Mechanical coarse purifiers - were in place to capture large particles;
• Absorption carbon – was used to capture odors and toxins;
• Electrostatic – which ionizes the air and attracts contaminants;
• HEPA – to capture even the smallest particles;
• Ultraviolet – designed to sanitize the air, as well as oxidize harmful compounds to carbon dioxide and water.

Basic type of air purifier

The simplest way to purify is to run the air through a coarse purifier and a carbon purifier. Thanks to this scheme, it is possible to get rid of unpleasant odors and remove relatively large particles of contaminants such as droplets or animal hair from the air. Such models are cheap, but there is no special effect from them. After all, all bacteria, allergens and small particles are still unfiltered.

Electrostatic air purifiers

With these devices, the principle of cleaning is a bit more complicated. Air passes through the purifier's electrostatic chamber, where contaminated particles are ionized and attracted to plates that have opposite charges. The technology is relatively inexpensive and does not require the use of any replaceable purifiers. 

Unfortunately, such air purifiers cannot boast of high performance. Otherwise, due to the volume of ozone formed on the plates, its concentration in the air will exceed the allowable level. It would be strange to fight one pollution, actively saturating the air with another. Therefore, this option is suitable for cleaning a small room that is not subject to heavy pollution.

HEPA air purifier

Contrary to popular belief, HEPA is not a brand name or a specific manufacturer, but simply an abbreviation of the words High Efficiency Particulate Arrestance. HEPA purifiers are made of an accordion-folded material whose fibers are interwoven in a special way. 

Pollution is captured in three ways:

• Inertia: particles larger than one micron in diameter enter the purifier with the air flow and cannot bypass the barrier. As a result of inertial motion, they become trapped in the purifier.
• Diffusion: light and small particles (less than 0.1 µm in diameter), due to their chaotic motion, settle on the purifier fibers, while the rest of the airflow flows around the obstacle and cannot pick them up.
• Entanglement: particles too large for diffusion and too small for inertia fly with the main flow. However, some of them still cling to the fabric fibers and remain. New particles stick to the glue and so on. 

Photocatalyst air purifier

A few years ago, a promising field of so-called photocatalytic cleaners emerged. In theory, everything was pretty rosy. Air through a coarse purifier enters a block with a photocatalyst (titanium oxide), where harmful particles are oxidized and decomposed under ultraviolet radiation.

It is believed that such a purifier is very good at fighting pollen, mold spores, gaseous contaminants, bacteria, viruses and the like. Moreover, the effectiveness of this type of cleaner does not depend on the degree of contamination of the purifier, because the dirt does not accumulate there.

However, at present, the effectiveness of this type of purification is also questionable, because photocatalysis is only on the outer surface of the purifier, and for a significant effect of air purification, it requires an area of several square meters at an intensity of ultraviolet radiation of at least 20 W/m2. These conditions are not met in any of the photocatalytic air purifiers produced today. Whether this technology is recognized as effective and whether it will be modernized will tell.