Design and Testing of a New Size Classifying Isokinetic Sequential Aerosol Sampler

Abstract

Two versions of a size-classifying isokinetic sequential aerosol sampler (SCISAS) have been designed, built, tested, and deployed in a field program in the southwestern US. The SCISAS units can operate at unattended sites, exposing four or more filter types simultaneously, in two size ranges, for six sampling time intervals. Design considerations included theoretical estimates of aerosol particle losses in the 0-15 {mu}m size range. SCISAS prototypes have been tested to evaluate their sampling efficiency as a function of flow rate, the sensitivity of the sampling efficiency to isokinetic matching within the SCISAS sampling stack, the equivalency of their sampling ports, and their passive deposition characteristics. The prototypes were also compared to several other types of aerosol filtration samplers already in common use. These tests show that particle loss mechanisms within the SCISAS usually cause no more than 5% losses, and that the SCISAS units agree, within one to two measurement uncertainty intervals, with other types of aerosol samplers.