Air filter

Air filter :

A particulate air filter is a device composed of fibrous materials which removes solid particulates such as dust, pollen, mould, and bacteria from the air. A chemical air filter consists of an absorbent or catalyst for the removal of airborne molecular contaminants such as volatile organic compounds or ozone. Air filters are used in applications where air quality is important, notably in building ventilation systems and in engines.
Some buildings, as well as aircraft and other human-made environments (e.g., satellites and space shuttles) use foam, pleated paper, or spun fiberglass filter elements. Another method, air ionisers, use fibers or elements with a static electric charge, which attract dust particles. The air intakes of internal combustion engines and air compressors tend to use either paper, foam, or cotton filters. Oil bath filters have fallen out of favor. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluid dynamics of the air-compressor part of the gas turbines.

Paper air filter

Filters made of paper offer filtration and air flow.  They are generally cheaper, but have to be replaced every 5,000 to 10,000 miles. 

Gauze Air Filters

Gauze air filters

Gauze style air filters offer filtration and air flow. There are 2 types: oil based and dry gauze filters. The biggest advantage of a gauze style air filter is that they're designed to last the life of the vehicle. However, this requires you to regularly clean the air filter with the manufacturer's recommended air filter cleaning kit. Oil based gauze filters tend to filter better then dry but have to be oiled. Whereas, dry gauze filters don’t need to be oiled, but the filtration generally isn’t the best. Each air filter manufacturer makes their gauze filters differently. Most have between four and seven layers of gauze depending on the brand and style of filter.

Foam Air Filters

Foam air filters

Foam air filters are gaining in popularity and offer both filtration and air flow. Foam filters are very successful in dirt track racing because of their ability to filter dirt while maintaining air flow. These foam style air filters are designed to last the life of the vehicle, provided you follow the manufacturer's cleaning instructions. These filters need to be oiled, just like oil based gauze filters.

How air filter works