Air is drawn vertically through an impaction orifice mounted in the upper case of the instrument, where particles are separated from the air-stream with an efficiency greater than 90 per cent for those particles having an aerodynamic diameter of 5 µm and above. The continuous movement of the glass slide below the orifice can be pre-set at 2 mm/h over 24 hours - 4 mm/h over 12 hours - or 8 mm/h over 6 hours. The total travel of the slide is 48 mm.

Operating on 12 v a.c. through a mains converter, the sampler is completely safe in domestic or hazardous areas. The 9100 is fitted with its own pump unit producing a quiet and smooth air movement. Many safety features are included to prevent misuse by non-technical personnel.