Electret filter

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An electret filter is a gas filter whose fibers are manufactured in such a way that they carry electrical charges or have permanent electrical polarization . Electret filters have only been studied in theory and practice since the 1980s. They are used, among other things, in air conditioning and ventilation technology and in breathing masks .

Electret filters are depth filters and are usually made of polymer fibers . Particle deposition on electret fibers occurs in the case of uncharged particles due to influence and in the case of charged particles due to the Coulomb force . In particular, for particle diameters smaller than 1 µm, electret filters can achieve higher degrees of separation compared to uncharged filters . With increasing particle deposition on the fibers, these are shielded and the electrostatic separation effect decreases.

literature

  • Richard C. Brown: Nature, Stability, and Effectiveness of Electric Charge in Filters. In: Kvetoslav R. Spurny : Advances in Aerosol Filtration. Lewis Publishers, Boca Raton 1998, ISBN 0-87371-830-5 , pp. 219-240.

Individual evidence

  1. ↑ Frank Jordan: Investigations into the particle separation behavior of submicron particles in fiber filters in an electric field . Dissertation, Duisburg 2001. p. 1.
  2. ↑ a b c d Réda Lathrache, Heinz Fißan: Fundamental investigations into the separation behavior of electret filters - Part 1: Determination of the degree of separation . Dust - cleanliness. Luft , 49 (1989) No. 9, pp. 309-314.
  3. ↑ VDI 3677 sheet 2: 2004-02 Filtering separators; Depth fiber filters (filtering separators) . Beuth Verlag, Berlin, p. 24.
  4. ↑ Réda Lathrache, Heinz Fißan: Fundamental investigations into the separation behavior of electret filters - Part 3: Change of the filtration properties due to particle loading . Dust - cleanliness. Luft , 49 (1989) No. 11, pp. 407-411.