Air Filters - Home Filtration Systems

Written by Norene Anderson
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Air filters are made in several designs. One of these designs is the fibrous filter. This filter is made with fibers running vertical to the airflow direction. The porosity is high due to the construction of the design. The smallest fibers are submicrometers and the largest are 100 mm. Plastic, glass, and wood make up the majority of fiber content. Fibrous filters offer a velocity of about 10 cm.

Porous filters are another type of air filter designs. These filters have less porosity than the fibrous filters with a porosity level of 50 percent to 90 percent compared to 70 percent to 99 percent for fibrous. The pore structure is complex causing the gas inside to follow an irregular path. The efficiency of porous filters is high. The materials for this type of filter include polyvinyl chloride, cellulose esters, Teflon, sintered metals, and other types of plastics.

Ways to Clear the Air

Allergies and allergy-related illness is at an all-time high. More pollution is getting into the air being circulated in the home. Studies have shown that there are more pollutants inside the home than outside the home. This makes perfect sense when you consider that the inside air is circulated repeatedly. If it is not cleaned or purified during the recirculation process, the pollutants will continue to multiply. Making the right choice in air filters is essential to having clean air.

The most common disposable air filters are fiberglass or polyester, one inch thick, and designed to be replaced monthly. This type of filter is mostly for protecting the heater and air conditioner from becoming filled with harmful particles. It is not very useful for removing small pollutant particles from the air. The washable or reusable filter offers about the same protection for airborne particles. Check the label to see the manufacturer's rating for air purification.

More Designs for Air Filters

To find air filters designed to capture small particles, the flat or pleated filters made of polyester or cotton are the better choice. They are denser than fiberglass. These are one-inch filters that will need changing four to six times a year. The deep-pleated filters are more efficient in reducing the air pollutants. They last longer than the thinner filters. The thicker filters require systems specifically designed for the five or six inches needed for the filter.

The permanently charged, pleated electrostatic filter is even more efficient due to the design to capture the tiniest particles. The electrostatic charge holds particles that would otherwise escape. The use of the combination of pleated membranes in the filter and the electrostatic charge is highly effective in cleaning the indoor air.

Uses for Air Filters

Air filters are used to remove bacteria, pet dander, pollen, mold spores, and other harmful particles and allergens from the indoor air. Improving the quality and cleanliness of the air will decrease the occurrences of allergy symptoms. It is especially important if there is someone in the home with asthma to have a highly efficient filtering system to purify the air.

Filters are given a MERV (Minimum Efficiency Reporting Value) rating to establish minimum efficiency values. It identifies the size of particles the filter is designed to capture. There are 16 levels of MERV ratings. If you know the type of contaminants or particles you need to capture, it is easy to identify the best air filter for the job by understanding the MERV ratings.


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