Air Filters: What Is It? How Does It Work? Types, Uses

Air filters and purifiers eliminate allergens from your home's air. Several types of air filters are available, with some performing better than others. An air filter is put in your heating, ventilation, or air-conditioning system to purify the air throughout your house.

What are Air Filters?

Air Filters remove airborne particles, pollutants, and germs that harm human health and the environment. Air Filters in industrial facilities safeguard essential equipment from harm while preserving the quality of goods and supplies. These are widely used in cleanroom conditions to reduce particle count. Exhaust and stack gases are filtered and purified before being discharged into the environment. Many houses, businesses, commercial buildings, labs, clinics, and hospitals include air filters.

It removes dust, filth, smoke, aerosols, smells, viruses, moulds, germs, hazardous gases, and other particles and contaminants that may occur in ambient air. These pollutants cause and exacerbate respiratory problems, skin disorders, allergies, and other ailments.

Do Air Filters Really Work?

Yes! However, it is vital to understand what they can and cannot accomplish. Air purifiers intend to remove contaminants from the air, including allergies, dust, spores, pollen, and other pollutants. Some purifiers collect or decrease germs, viruses, and smells as well. Not all units, however, will be able to do so. Furthermore, it is critical to recognise that not all units can capture volatile organic molecules. Aerosol sprays and ordinary home cleansers include this.

If you suffer from allergies or asthma, an air purifier can help since it eliminates common allergens. However, it can only eliminate allergens in the air; it cannot remove allergens embedded in furniture or floors. It is essential to replace the filters on your air purifier regularly if you want it to perform correctly. Most manufacturers will provide you with helpful advice. However, the precise time varies on several factors, including consumption and air quality.

When utilising an air purifier, it's also crucial to be practical. Many firms may claim that their products are 99 per cent efficient. However, their performance may differ because air purifiers evaluate in controlled environments. The location of the unit is also essential in terms of its effectiveness. When installing your new air purifier, please read the instructions carefully to ensure the correct installation.

Some units need a specific amount of space between them and the wall, whilst smaller units may typically mount on a table or desk.

Types of Air Filters

• Hepa Air Filter

The HEPA filter, also known as the high-efficiency particulate absorption filter and the high-efficiency particulate filter, is an air filter efficiency standard. Filters that fulfil the HEPA standard must meet specified efficiency requirements. According to industry requirements, a HEPA air filter must remove at least 99.95% or 99.97% of particles from the air that flows through it. HEPA filters are randomly organized mats of fibers. These filters are tangled bundles of fine fibres.

When the most oversized particles travel through this channel, the fibre bundles act like a household sieve, physically preventing the particles from flowing. When smaller particles float through the air, however, as the air twists and turns, the smaller particles cannot keep up with the motion of the air and collide with the fibres. The tiniest particles have extremely little inertia and constantly move around the air molecules as though battered by them.

• Pleated Air Filter

Folds or wrinkles in pleated air filters enhance the filtering surface area. They are housed in a frame or cartridge that preserves the pleated shape of the filter. Pleated air filters capture tiny and microscopic particles well. Because they can catch small pollutants such as odour, bacteria, pollen grains, moulds, and other allergens, they have high filtering efficiency and significantly enhance indoor air quality. Pleated air filters are made of pliable materials such as paper, polyester, fabric, and cotton.

However, they tend to restrict airflow due to their material density. As a result, the motor of HVAC unit or air filter equipment has to work harder to push the air out of the filter media, resulting in greater energy consumption. Pleated air filters cost more than non-pleated air filters. HVAC systems are adjusted to accommodate the usage of pleated air filters.

• Non-Pleated Air Filter

Non-pleated air filters offer a smaller filtering surface area. They work well with more significant air pressures and volumetric flow rates. Typically, they construct of woven fiberglass or electrostatic material. They are less expensive than pleated air filters but have a shorter service life and must be replaced or cleaned more frequently. Non-pleated air filters are only effective at trapping big particles (e.g., dust, trash, and insects); hence, they are not ideal for people with respiratory disorders or allergies.

• Paper Air Filter

Paper is the least costly yet least long-lasting filter media material. By enabling air to flow through its narrow pores, paper air filters allow minute particles to be separated. They are typically made by compacting woven wood pulp fibres together and then pleating them to increase mechanical strength and filtering effectiveness. They're common in car air cleaners, furnace filters, and interior air purifiers.

Mechanism of Air Filters

To catch particles, HEPA filters use a combination of three mechanisms:

• Impaction

This occurs at the filter media's surface to sift particles more significantly than the mesh holes of the filter media. These particles collide with the fibres and are immediately collected. This method is for particles larger than 1 micron in size.

• Interception

Particles not sieved at the filter medium's surface migrate to the filter medium's depth. These particles, however, collide with the fibres and are removed from the airflow.

• Diffusion

When very minute particles come into contact with gas molecules, they travel wildly through the filter media, finally striking and sticking to the fibres. Brownian motion is the name given to this phenomenon. Interception and diffusion are the two most prominent filtering processes for particles with sizes close to the MPPS.