Contaminated air is sucked into the inlet (1) in the lower section of the filter unit and passes through filter stage 1 (2), where the majority of the oil particles are trapped.Filter stage 1 gets saturated and the oil drops into the bottom of the filter unit, which acts as a col¬lection container. From there, it is pumped (8)(accessory, not A•smoke²⁰) or drained away. The air passes through an additional Absolent filter (3), where the remaining bigger particles are filtered out and on via a HEPA filter (4) to the external fan. Generally the air is now free from particles and can be returned directly to the premises.