Aerosol Messgeraete
Berner Impaktoren
The Berner low pressure impactor was designed to provide sufficient sample for gravimetric determinations of aerosol mass distributions, and for chemical analyses requiring sample extraction. There are several models, with flow rates from 2l/min to 150 l/min.
The most commonly used models are LPI 30/0,06 and LPI 25/0,018 which are multijet impactors with a flow rate of 30 l/min (25 l/min respectivly), as measured at the inlet temperature and pressure.
Except for the first stage (as an example for the model LPI 30/0,06), the impactor has between 7 and 130 equal-diameter jets per stage. The jets are arranged in a circle. The collection plate has a large hole in the center for the air to pass to the subsequent stage.
This flow arrangement gives a symetrical flow pattern, and thus deposits under each jet. The final flow rate through the impactor is controlled by a critical orifice downstream of the final collection stage.