Different Types of Air Filters Explained

If you want better indoor air quality, then you need a quality air purifier. Air purifiers reduce the airborne allergens that aggravate allergies and asthma. As dirty, contaminated air flows through the air purifier, fresh, clean air flows into your home. The type of air filter in an air purifier determines how the air purifier works – and how well it works.

HEPA Filters

HEPA air filters set the standard for air cleaners today. In the 1940s, the US Atomic Energy Commission developed HEPA (High Energy Particulate Air) filters in an attempt to filter radioactive contaminants. To be classified as a HEPA filter, it must capture a minimum of 99.97% of pollutants at 0.3 microns.

HEPA filtration captures particles 25-50 times smaller than the eye can see. The ultra-fine fibers in HEPA filters capture microscopic particles through a combination of diffusion, interference, and inertial impaction. With smaller particles, diffusion occurs when the random motion of the particles causes them to collide with fibers. Interception occurs when larger particles directly collide with a fiber. When a particle's inertia leads to its collision with a fiber, this is known as inertial impaction.

HEGA Filters

You may have also heard of HEGA or High Efficiency Gas Adsorber filters. Specific to Austin Air, HEGA filters must exhibit a minimum efficiency of 99.9%, per standards of the Institute of Environmental Sciences, and use "adsorber" filtration to filter out chemicals, gases, and odors.

Adsorber filtration combines carbon or carbon / zeolite pellets into a carbon cloth filter to trap gaseous particles. Specific to the HEGA filter, the adsorber filtration method must be designed, built, filled and packaged to adhere to these specific standards. The HEGA air filter must also remove irritants like dust, pollen, mold spores, bacteria, and pet dander to be considered a HEGA filter.

The Austin Air Allergy Machine Series include HEGA filtration. Austin Air discovered and developed the new HEGA technology, which involves weaving carbon into a lightweight cloth. The Austin Air Allergy Machine is the ideal air purifier for someone who wishes to remove gases, vapors, and odors as well as allergens and other particulate matter.

Activated Carbon Filters

Activated carbon filters remove gases, odors, and chemical toxins. Carbon, or activated charcoal, is treated with oxygen to open up the millions of tiny pores between the carbon atoms.

The activated charcoal adsorbs odorous substances from gases or liquids. The term "adsorbing" refers to the way the pollutants attached to the charcoal by chemical attraction. The large surface area of ​​the activated charcoal gives it thousands of pores for trapping pollutants. As chemicals and pollutants pass the carbon surface, they are immediately attracted and captured within the filter.

Some carbon filters are treated with additional chemicals like potassium iodide or potassium permanganate which improve the carbon filter's ability to capture Volatile Organic Compounds (VOCs) and other chemically reactive gases. Activated carbon filters adsorb a wider spectrum of contaminants.

AllerAir air purifiers use an activated carbon filtration system to effectively clean indoor air. AllerAir models feature a cylindrical shape for maximum air flow, an effective four-stage filtration system, and a quiet fan.

Electrostatic Filters

Like Activated Carbon filters, Electrostatic filters attract pollutants. Instead of carbon, Electrostatic filters use electrostatic charges to clean the air. Electrostatic charges are created by pushing air through a maze of static concrete fibers. As airborne particles move past the static concrete fibers, they become attracted to the static charge and are captured within the filter. The particles remain on collector plates until they are hand washed or removed by a HEPA vacuum cleaner.

By using static electricity, you never have to worry about replacing the filters, as most electrostatic air cleaners use collection plates to capture pollutants and can be cleaned easily. However, the collection plates must be cleaned frequently to ensure effective air cleaning. Also, unlike HEPA filters, some electrostatic filters emit ozone, a dangerous lung irritant that can trigger asthma and allergy symptoms, as well as other respiratory issues.

Procuring an air cleaner that does not emit any ozone increases the amount of truly clean air in your home. Friedrich air purifiers have the best electrostatic filter on the market and emit minimal amounts of ozone.

Charged Media Filters

Charged media filters also utilize electrostatic energy. Made from synthetic fibers, the media filter is charged through the manufacturing process and retains the charge during its use. This charge links airborne particles, giving them an electrostatic charge before trapping them within the fibers of a conventional filter.

Charged media filters present relatively low energy costs and are extremely efficient. However, as the filter becomes soiled, it becomes resistant to the airflow, making it less efficient the more soiled it becomes. Therefore, charged media filters must be changed regularly for peak performance.

Charged media air cleaners are known for their energy-efficiency and quietness; however, some of them may emit ozone. Blueair air purifiers utilize the best charged media filtration, do not emit ozone, and are extremely quiet and efficient.

Hybrid Air Filtration Systems

The Hybrid air filtration system maximizes its effectiveness through the use of multiple technologies. Hybrid air purifiers use a combination of filtration methods, each filter adding to the overall effective quality of the air purifier. Most effective air purifiers use combinations of the filters listed above.

The combination of air filtration systems is the next revolutionary step to cleaner indoor air quality. However, each filter type presents its own unique sphere of air cleaning. It's important to determine what your air cleaning needs are and to research and find the filter that will work best for you and your needs.

Source by M. Scott Smith

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