Comparative Evaluation of Commercially Available Liquid Aerosol Generators for Implementation in the Ambient Air Test Facility (AATF)

Abstract

Accurate and stable aerosol generation is essential for evaluating chemical sensor performance. This requires controlled laboratory conditions that replicate operational environments. This study presents a comparative assessment of four commercially available liquid aerosol generators—the Collison nebulizer, Blaustein Atomizing Module (BLAM), Aeroneb Lab module, and P&S T45 vibrating mesh nebulizer—for their ability to generate well-characterized aerosols for eventual integration into the U.S. Naval Research Laboratory’s Ambient Air Test Facility (AATF). The objective was to identify systems capable of producing stable, tunable aerosol output under laboratory conditions with particle size and concentration characteristics relevant to high-flow test environments. Aerosols of sodium chloride (NaCl) and glycerol at concentrations ranging from 0.1–2.5% mass were generated and analyzed using a TSI Aerodynamic Particle Sizer (APS 3321). Performance metrics included particle number concentration (#/cm3), mass concentration (µg/m3), number median diameter (NMD), mass median diameter (MMD), and geometric standard deviation (GSD). The P&S T45 vibrating mesh nebulizer produced the highest particle concentrations with controllable aerosol concentration via duty cycle and flow rate adjustments, while atomizers such as the Collison and BLAM exhibited narrower size distributions (GSD ~1.25) but were more sensitive to solution viscosity and clogging at concentrations > 0.5 wt%. Operating windows were established for each generator by defining thresholds for stable aerosol output. Comparison of number versus mass-weighted size distributions underscores the need to evaluate additional metrics for accurate dose characterization. This study provides quantitative guidance for selecting aerosol generators and establishes a reproducible framework for evaluating generator performance under conditions relevant to future AATF integration.

Keywords: Aerosol generator, Vibrating mesh, Atomizer, NaCl, APS, Particle size distribution