AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Design and Operational Optimisation of Pneumatic Sampler for Resuspension Chamber
MIROSLAV KLÁN, Jan Hovorka, Martin Civiš, Charles University in Prague
Abstract Number: 536 Working Group: Instrumentation and Methods
Abstract The generation, capture and measurement of aerosol particles in a controlled laboratory environment are very important for determining the emission potentials of different sources of dust and for defining the physical characteristics, chemical composition and toxicological risk connected with the emission of particles into the atmosphere from specific locations or source materials. Therefore, we constructed metallic cylindrical resuspension chamber (V=0.437 m$^3, S=0.35 m$^2) to disperse solid samples under well-defined temperature and humidity. The chamber allows on-line measurements of particle number size distribution of aerosolized samples and subsequent sampling of size segregated particles on filter media. Repeatability of the resuspension experiments strongly depends on the way of introduction of a solid sample into the chamber. For this purpose a pneumatic sampler was optimised. The sampler was positioned at centerline near the upper third of the chamber and consists of electronically controlled air-jet and rotating five-hole carousel. Optimal air pressure and injection time of the jet were 15 bars and 10 milliseconds respectively. Optimal sample mass was about 5 mg. Ultrapure SiO$_2 and Al$_2O$_3 of well-defined grain size were used as a standards. Environmental samples were dried at 48°C for 24h and pre-sieved with Tyller sieve (mesh size 38 micrometer). Fully automatic regime of the sampler allows conducting consecutive dispersion of five samples. Since each of resuspension experiments usually takes about two hours, use of the sampler allows about 10 hours of conducting experiments without the need to open the chamber, which greatly improved experiment repeatability.
The financial support by the Czech Grant Agency (P503/12/G147) is greatly acknowledged.