Measurement and Classification of Submicron Particles by Differential Mobility Analyzer and Screen-type Diffusion Battery

Abstract

Performances of a Differential Mobility Analyzer (DMA) and a Screen-type Diffusion Battery (SDB) for the measurement of submicron particles are studied, and the applicability of these instruments for the generation of submicron test aerosols is investigated since both instruments measure particle size after classifying particles according to electric mobility and Brownian diffusivity, respectively.
As a sizer, both DMA and SDB have sufficient performances for submicron particle giving the same measurement result of particle size. As a generator, (1) DMA classifies aerosol into monodisperse particles (geometric standard deviation σ_g<1.1) with low concentration. It is, hence, preferable for the generation of very monodisperse aerosol unless high concentration is required. (2) SDB is not preferable for the generation of monodisperse aerosols by itself since the classification characteristic is poor in large particle size region. Thus, SDB is combined with an inertial classifier (parallel fiber screens), and it makes it possible to generate high concentration aerosol with fairly high monodispersity (σ_g≈1.5). Therefore, the combination of SDB and parallel fiber screens is recommended for the generation of a fairly monodisperse aerosol if high concentration is required.