Single-stage flowing liquid film impactor for continuous on-line particle analysis

A single-stage “wet impactor” is presented, where the impaction occurs on a regenerated water surface. The developed impactor is equipped with an impaction liquid support plate of etched glass and a drain spout providing a continuous liquid flow covering the impaction area. Subsequent transport of the impaction liquid makes an on-line determination possible. With multiple nozzles (74 holes, 0.3 mm i.d.) and an air flow of 101/min the cut-off was determined to 0.41 ± 0.02 μm. The impactor was also investigated for its particle loss. The cut-off function, regarding the consequences of letting impaction occur in a liquid film is discussed and compared to conventional impactors. The analysis technique was tested in an ambient air measurement study with an ion chromatograph attached to the sampling system.