PROTON filtering unit is designed for cleaning the air form dust contamination and oil mist. The appliance is irreplaceable for extraction of mist and fumes arising at stands of metal processing, emulsion mists applied for tool cooling by means of water-oil emulsion, as well as for welding – especially during welding of oil-laden steel sheet and welding with use of high amounts of anti-spattering preparations. The appliance is not designed for extraction of electrical conductivity dust particles. The device can work with a system of local exhausts that extract the dust contamination from several points, whereby the air stream is cleaned centrally and distributed back to the process hall as clean air, afterwards. Maximum temperature of the conveyed air should not exceed +60ºC. The appliance can be installed both, inside and outside the building.