A Bench-Scale Aerosol Test Chamber

Abstract

This paper describes the design and evaluation of a bench-scale aerosol test chamber. Although originally designed for respirator testing, the chamber has broad applications for industrial hygiene research, testing, and calibration. The 109 L chamber includes a top mixing section, a honeycomb flow laminator section, a 52 L transparent plastic aerosol test section, and a bottom exhaust plenum. Overall chamber dimensions are 0.6 × 0.6 × 1.5 m high. Airflow velocity was uniform within ± 20% of the mean throughout the test section. A uniform aerosol concentration was achieved in the test section by opposed jet mixing in the mixing section. Test aerosol concentrations in the chamber were uniform within ± 15%, and concentration was stable to within ± 5% for more than one hour. Measurements were made with a GCA Model RAM-1 instrument and based on perpendicular 8-point traverses. Similar uniformity (within ± 5%) was found for 12 μm and 24 μm monodisperse particles. Chamber pressure can be controlled from slightly negative to slightly positive relative to ambient pressure. The air velocity in the test section is sufficiently low (approximately 4 cm/s) that it is equivalent to still air for most aerosol sampling situations. Although the chamber is routinely used with aerosol particles ranging from 0.1 to 12 μm no significant build-up of aerosol liquid has occurred anywhere in the system.