AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Comparison of the Grimm 11-R Mini Laser Aerosol Spectrometer to the TSI 3321 Aerodynamic Particle Sizer
CHIH-HSIANG CHIEN, Alex Theodore, Chang-Yu Wu, Yu-Mei Hsu, Brian Birky, University of Florida
Abstract Number: 657 Working Group: Instrumentation and Methods
Abstract A new optical particle counter (OPC), 11-R Mini Laser Aerosol Spectrometer, was compared with the TSI 3321 aerodynamic particle sizer (APS) for particle sizing. The new OPC is the next generation of Grimm 1.109 Portable Aerosol Spectrometer which has been broadly used in environmental, industrial and occupational aerosol monitoring due to its portable design, real-time monitoring, and cost effectiveness. However, not only the particle size but also the refractive index of material influences the scattering response, resulting in concern about the accuracy of particle sizing. Furthermore, while the OPC reports size distribution in optical diameter, it is widely assumed that the optical diameter is equivalent to its volume equivalent diameter. For example, the count size distribution has been integrated to compare with mass-based measurement such as PM$_(2.5).
Monodisperse liquid oleic acid and solid sodium chloride aerosols in the range of 1 to 20 micro-meter generated separately by a vibrating orifice aerosol generator were measured by the OPC and the APS in parallel to compare their performance. The results showed that the OPC’s optical diameter was not equivalent to the volume equivalent diameter converted from the APS’ aerodynamic diameter, and the relationship was in a non-linear fashion. For oleic acid aerosol, the volume equivalent diameter was generally slightly larger than its optical diameter. However, the optical diameter for sodium chloride was much larger than the volume equivalent diameter. For example, the optical diameter of 9.9 micro-meter for sodium chloride was reported as a volume equivalent diameter of 7.3 micro-meter via APS. Experimental calibration equations for oleic acid and sodium chloride from 1 to 20 micro-meter were established to quantify the difference. With such a calibration, the OPC reported the same penetration profile of a commercial respirable sampler as prior studies using the APS did, proving the effectiveness of the calibration.