An air filter is the device which removes particulate solids like pollen and dirt from air. Air filters find utility where quality of air is of high importance, especially in ventilation systems of buildings and the engines such as those of internal combustion, gas compressors, compressors for air tanks, gas turbines and others.
Buildings, aircrafts and other environments use filters from foam, paper folding, or fiberglass cross. Another method uses fiber or the elements with static electrical charge which attracts particle powder. There are four major types of materials used for mechanical air filters as;
3. Synthetic fibers
Air filters are found in most systems of forced air flow (air conditioning). The efficiency of air filters in such systems significantly influences the quality of indoor air.
Recommended by the construction industry and government guidelines as the standard recommend the use of air filters to meet minimum requirements. In the United States, for example, the United States Department of Energy recommends a Minimum Efficiency Reporting Value, MERV of 13 as stipulated in the test protocol ASHRAE 5.2.2- 1999, and LEED advises builders much as. While the ASHRAE recommends air filters with MERV 6 or higher to control the amounts of pollen, mold and dust reaching wet batteries evaporator systems of air conditioning. Wet batteries are contaminated with high levels of pollen and dust and can promote the growth of mold colonies.
Since the efficiency drops below a certain level of dirt, the filters require maintenance. There are different types of filters available for air conditioning systems. Many of them are cheap but not very efficient. Many filters assembled inside the ducts for air conditioning in buildings are made of glass fiber cross. These filters are inexpensive, disposable, and are available in different densities and sizes. Low density filters allow greater airflow but filter less dirt. On the other hand, the high-density filters withholds particles but allow less air flow and therefore become dirty earlier.
The polyester or fiberglass are frequently used for the manufacture of air filters. Both materials are suitable for temperatures up to 120° C, and its use is common in residential, commercial and industrial applications. Polyester and fiberglass can be mixed with cotton or other fibers to produce a wide range of material characteristics. In some cases, the polypropylene has lower tolerance to high temperatures and is used to improve chemical resistance. Tiny synthetic fibers known as microfibers are used in many types of filters like High Efficiency Particulate Air (HEPA).