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Sunday, August 2, 2009
Air Filters
Paper-element air filters were first introduced in 1957. The air cleaner element is the disposable dry type, which is made up of a cylindrical cellulose fiber material, pleated to permit the greatest filter area. On each end of this cylinder, the fiber is embedded in end plates to provide an efficient dust seal. On each side of the fiber, rust resistant wire screen furnishes compressive strength. The fine mesh located on the inner screen also acts as a flame arrester in case of backfire. The fiber passes air through the filter with low restriction, but any dust or dirt in the air is deposited on the pleated outer surface. The filter fiber is flame proof and keeps its filtering efficiency under normal concentrations of gasoline vapors, engine oil and water vapor, but should be changed at normal lubrication periods. Air filters can be cleaned by blowing compressed air back through the filter, but the danger exists that small holes can be created by excessive pressure. For this reason, it is usually a good idea to simply replace the filter element. Some air filters are of the washable variety, and can therefore be washed clean and re-used. A good way to determine if your air filter is still OK is to look through the filter on a bright day. If you can't see the sun through the filter, it needs replacement.