HEPA air filter is a type of highly efficient air filter that is used in most room air purifiers available today. HEPA stands for High Efficiency Particulate Air and the most commonly used in air purification are Flanders filters.
HEPA air filters are created by interlacing fine fibers in a random order inside an air purifier. These fibers serves as the main air filter system of a HEPA filter. The fibers used for it are made from fiberglass material with diameters ranging from 0.5 to 2.0 microns to ensure strict screening of dirt and gaseous air pollutants.
HEPA air filters are similar to a sieve but with grains for air space not bigger than 0.3 microns. Air stream passes through it and air particulates bigger than 0.3 microns are trapped and not allowed to leave the filter or purifier. Oftentimes, the trapped contaminants stick to the fibers of the HEPA air filter which requires users to clean the air filter as often as possible for efficient air purification.
Mechanisms Used by HEPA Air Filters
When the air flows in a single stream, larger air particulates tend to get screened out from the stream. Thus, when the air stream hits Flanders filters, the air output is cleaner than before. This mechanism is called interception.
When large air particulates are not able to avoid the fibers that make up the HEPA air filter, the particulates get stuck in the air gaps of the filter. Infrequent cleaning of the air filter causes clogging and therefore makes the air filtration system ineffective. This mechanism is called impaction.
An improved mechanism used in HEPA air filters is by causing a delay in the travel time of very small air particulates with sizes usually below 0.1 microns. Delay in the travel time of these particulates increases the chance that they can get trapped by interception or impaction. This mechanism is called diffusion. Flanders filters are known to use this HEPA filter mechanism.