Browsing by Author "Tsai, Perng-Jy"

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Dustiness test of nanopowders using a standard rotating drum with a modified sampling train
(2009-01-01)
Tsai, Chuen-Jinn
;
Wu, Chien-Hsien
;
Leu, Ming-Long
;
Chen, Sheng-Chieh
;
Huang, Cheng-Yu
The standard rotating drum tester was used to determine the dustiness of two nanopowders, nano-TiO(2) and fine ZnO, in standard 1-min tests. Then, the sampling train was modified to determine the number and mass distributions of the generated particles in the respirable size range using a Scanning Mobility Particle Sizer (SMPS), an Aerodynamic Particle Sizer (APS) and a Multi-orifice Uniform Deposit Impactor (MOUDI) in the 30-min tests. It was found that very few particles below 100 nm were generated and the released rate of particles decreased with increasing rotation time for both nanopowders in the 30-min tests. Due to the fluffy structure of the released TiO(2) agglomerated particles, the mass distributions measured by the MOUDI showed large differences with those determined by the APS assuming the apparent bulk densities of the powders. The differences were small for the ZnO agglomerates, which were more compact than the TiO(2) agglomerates.
Field Application of a Newly Developed Personal Nanoparticle Sampler to Selected Metalworking Operations
(2013-06-01)
Young, Li-Hao
;
Lin, Yun-Hua
;
Lin, Tzu-Hsien
;
Tsai, Perng-Jy
;
Wang, Ying-Fang
A personal nanoparticle sampler (PENS) that simultaneously collects respirable particles (< 4 mu m) and nanoparticles (< 0.1 mu m) has recently been developed and calibrated in the laboratory. This study aims to evaluate the performance of the PENS in the workplace, and to determine the exposure characteristics during selected metalworking operations. Metal polishing/buffing, spot welding, and milling operations were selected to represent sources of solid metal particles, fume aggregates and metalworking fluid mists, respectively. In each operation, personal samples of a side-by-side PENS and SKC respirable dust aluminum cyclone were taken concurrently with ambient particle number size distribution measurements. The PENS-measured respirable particle mass concentrations (PM4) showed remarkable accuracy with respect to the reference SKC cyclone, regardless of particle type. The PENS-derived nanoparticle effective densities agreed reasonably well with the bulk densities expected for the substrate and materials in use. During the metalworking operations, the nanoparticle mass concentrations (PM0.1) were poorly associated with the PM4 but strongly correlated with the ambient nanoparticle number concentrations (PN0.1), due to the persistent, elevated levels of nanoparticles formed during the operations. Overall, these results suggest that the PENS is applicable for use in the workplace to assess respirable and nanoparticle personal exposure, and that metal polishing/buffing, welding and milling generate a considerable amount of nanoparticles.