The contaminated air is collected by the collection

The contaminated air is collected by the collection unit (extractor hood, suction arm, hose, etc.) and transported into the filter unit directly or through a pipe or flexible hose. In the filter unit, the contaminant particles are filtered into different filter levels according to their size. 

Filter units that are equipped with a molecular sieve (for example activated carbon/BAC filters) remove the majority of gaseous contaminants. Afterwards the purified air can either be circulated back into the work area or diverted outdoors through an exhaust duct. 

Recirculating the air in the work area is a way to easily reduce energy costs.