Browsing by Author "Deshpande, CG"

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Electrostatic charge measurement and charge neutralization of fine aerosol particles during the generation process
(2006-04-01)
Tsai, CJ
;
Lin, JS
;
Deshpande, CG
;
Liu, LC
;
環境工程研究所
An aerosol charge analyzer has been constructed to measure the charge distribution of NaCl particles generated in the laboratory. A radioactive electrostatic charge neutralizer utilizing Po-210 was used to neutralize the electrostatic charge of the particles. The atomization technique was used to generate NaCl particles with diameters of 0.2 to 0.8 mu m, while the evaporation and condensation method was adopted to generate particles of 0.01 to 0.2 mu m in diameter. The experimental data demonstrates that the absolute average particle charge depends on the particle diameter, and is higher than that calculated by the Boltzmann charge equilibrium for particles within the range of 0.2 to 0.8 mu m. The charge increases with decreasing NaCl concentration. When these particles are neutralized using the Po-210 neutralizer, it is found that the electrostatic charge reaches the Boltzmann charge equilibrium. For 0.01. to 0.2 mu m NaCl particles generated using the evaporation and condensation method, test results show that the absolute average particle charge is higher than that calculated by the Boltzmann charge equilibrium for particles larger than 0.03 to 0.05 mu m in diameter, while it is lower than that predicted by the Fuchs theory [1], for particles smaller than 0.03 to 0.05 mu m. However, after charge neutralization, particles with diameter above 0.05 mu m reach the Boltzmann charge equilibrium condition, and the charges for particles with diameters of 0.010 to 0.05 mu m, agree well with Fuchs' theory.
Exposure assessment of organic solvents for aircraft paint stripping and spraying workers
(2006-03-01)
Uang, SN
;
Shih, TS
;
Chang, CH
;
Chang, SM
;
Tsai, CJ
The main objective of this study is to investigate the personal or area exposure of organic solvents during paint stripping and paint spraying. Three aircraft paint stripping/spraying workplaces in Taiwan were selected, and the Council of Labor Affairs and NIOSH recommended sampling/analytical methods used in this study. Activated charcoal tubes were used to investigate the personal and area exposure concentration of organic solvents in paint stripping and paint spraying operations. During aircraft paint stripping, experiment results show that methylene chloride personal exposure concentration at the ground area, 42.01 +/- 31.86 ppm, is higher than that at the working platform 4 M high above the ground, 20.41 +/- 11.43 ppm. Exposure concentration of methylene chloride in the initial paint stripping operation stage of every workplace is over the PEL (50 ppm) set by the Taiwan Council of Labor Affairs. Corrective actions are needed. During paint spraying, concentrations of all organic solvents were found to be below the PEL of OSHA. (c) 2005 Elsevier B.V. All rights reserved.
Sampling time effect on 2,4-Toluene diisocyanate concentration by using different samplers
(2006)
Tsai, CJ
;
Lin, HC
;
Lin, KY
;
Shih, TS
;
Chang, KC
In order to understand the sampling time effect on the 2,4-TDI (Toluene diisocyanate) concentrations, laboratory and field tests were conducted in this study. An ADS (annular denuder sampler) and two OFFCs (open face filter holders) with different filters were tested for 1 to 120 minutes in the laboratory using 2,4-TDI gas. In the field study, the standard sampling method, the dual filter the triple filter and annular denuder systems were used at two workplaces to study the change of 2,4-TDI concentrations with sampling time from 15 to 60 minutes. The test results in both laboratory and field studies show that the sampling time influences the sampled TDI concentration considerably which may be due to reaction of TDI with water vapor and polyo in the sampling process. It is evident that as sampling time increases the TDI concentration decreases very significantly.