The test material is fed from the cone shaped hopper at ca8 g/min (± 2 g/min) where it is dropped through a chute before it enters the countercurrent chamber.  A countercurrent of 0,05 m/s is created by a pump, which prohibits airborne particles to fall through into a collection bin.

Two particle size selective filters draw the airborne particles and segregate them into the inhalable and thoracle fractions  (Definition as per EN 481). For the inhalable fraction we use the BIA GSP heads, loaded with 10 mm x 50 mm filters, and for the thoracle fraction the FSP with 37mm membrane filters.