Hepafilter H14 78 mm bredde
History of HEPA. HEPA (High Efficiency Particulate Air) is the first micro filter standard that was designed during World War II by the United States Atomic Energy Commission. For catching radioactive contaminants from nuclear power testing laboratories the filters had to be able to remove at least 99.97% of particles 0.3 µm in diameter. Today, HEPA filter is more broadly applicable. In addition to purifying the contaminated air of nuclear power stations, there are many new usage possibilities in medicine, electronics, optics, and food industry, in science laboratories and in the social sphere.
The construction of a HEPA filter consists of a very thin and dense filter material folded into a wooden or metal frame. The filter material catches particulates of dust from the air that penetrates it. High filtering ability is achieved by very low speed at which the air penetrates the filter material. Maximal speed can not exceed 0.025 m/s. To achieve sufficient air speed through the face of the filter, it is necessary to fold the filtering material into the cassette as tightly as possible, but at the same time it should be noted that the filter resistance would not become too high. In a standard filter cassette in size 610 x 610 x 292 mm has c.a. 20 m² of filter material. The most used material is glass cloth, but also different fabrics of synthetic fibre can be used.
