Air Filters and Internal Combustion Engine Air Filters (1)

A particulate air filter is a device composed of fibers or porous material that removes solid particles such as dust, pollen,mold and bacteria from the air.Filters containing adsorbents or catalysts such as charcoal can also remove odors and gaseous pollutants such as volatile organic compounds or ozone.Air filters are used in applications where air quality is important,especially in building ventilation systems and engines.Some buildings, as well as aircraft and other man-made environments such as satellites and space shuttles,use foam,pleated paper,or spun fiberglass filter elements.Another method is an air ionizer,which uses electrostatically charged fibers or elements to attract dust particles.Air intakes for internal combustion engines and air compressors often use paper, foam or cotton filters.Except for niche uses,oil bath filters have fallen out of favor.The technology of gas turbine air intake filters has improved significantly in recent years due to improvements in the aerodynamics and fluid dynamics of the gas turbine air compressor section.

HEPA filter 

A high-efficiency particulate filter (HEPA),originally called a high-efficiency particulate absorber, and sometimes called a high-efficiency particulate filter or HEPA,is a type of air filter. HEPA-compliant filters are used in many applications,including cleanrooms in IC manufacturing,medical facilities,automobiles,aircraft,and homes.Filters must meet certain efficiency standards,such as those set by the U.S. Department of Energy (DOE).Different standards define the eligibility of HEPA filters.The two most common standards require that air filters must remove (from passing air) 99.95% (European standards)[4] or 99.97% (ASME standards) of particles sized greater than or equal to 0.3 microns.

Automotive cabin air filters

Cabin air filters are usually pleated paper filters that are placed in the outside air intake in the passenger compartment of the vehicle. Some of these filters are rectangular,shaped like an engine air filter. Others are uniquely shaped to fit the space available in a particular vehicle's exterior air intake.The first automaker to include disposable filters to keep the ventilation system clean was Nash Motors' "Weather Eye" in 1940.Beginning in 1959, reusable heater core filters were offered as optional accessories on Studebaker models, including the Studebaker Lark cars (1959-1966), Studebaker Gran Turismo Hawk cars (1962-1964) and Studebaker Champ trucks (1960- 1964).The filter is an aluminum frame containing an aluminum mesh that sits directly over the heater core.The filter is removed and installed from the engine compartment through a slot in the firewall. A long, thin rubber seal seals the notch when the filter is installed.Filters can be vacuumed and cleaned prior to installation.A clogged or dirty cabin air filter can significantly reduce airflow to the cabin vents and introduce allergens into the cabin airflow.Since cabin air temperature is dependent on the rate of air flow through the heater core, evaporator,or both,a clogged filter can significantly reduce the efficiency and performance of a vehicle's air conditioning and heating systems.Some cabin air filters do not perform well and some cabin air filter manufacturers do not print a Minimum Efficiency Reporting Value (MERV) filter rating on their cabin air filters.

Air Filters for Internal Combustion Engines

Combustion air filters prevent abrasive particulate matter from entering the engine cylinders, which would otherwise cause mechanical wear and oil contamination.Most fuel injected vehicles use a pleated paper filter element in the form of a flat sheet.This filter is usually placed inside a plastic box that is piped to the throttle body.Older vehicles with carburetor or throttle body fuel injection typically use cylindrical air filters, usually between 100 mm (4 in) and 400 mm (16 in) in diameter. It sits above or next to the carburetor or throttle body, usually in a metal or plastic container that may contain ducts to supply cold and/or warm intake air, and is secured with a metal or plastic cap.The whole unit (filter and housing together) is called the air cleaner.