Model 7.811 has been equipped with two internal pumps. One is responsible for the flow through the nebuliser (generation of a raw aerosol concentration); the other one provides dry air for an optional dilution and drying of the raw aerosol with help of silica gel drying.
The flow rates of both pumps can be controlled or switched on or off independent from one another. This is done via two switches and potentiometers on the front panel of the instrument. The dryer cartridge is mounted to the front and easily detaches to replace the wet silica gel with dry silica gel. Optionally, the dryer cartridge can be replaced with a standard hose system in case drying is not required or wanted.
A flow meter permits the monitoring of the dry air flow.
Different aerosols can be stored in up to six different nebulisers (for DOP, DEHS, Latex, ACFT, etc.), which permits a quick converting from one aerosol to another. They are all located inside a detaching cover mounted to the back of the unit (refer to picture below).