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KMID : 0365220120490020059
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Korean Journal of Public Health
2012 Volume.49 No. 2 p.59 ~ p.70
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Pressure Drop and Filtration Efficiency Differences between Single Type Filter and Dual Type Filter Particulate Respirators using Welding Fumes and Sodium Chloride
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Yoon Chung-Sik
Cho Hyun-Woo
Park Dong-Jin
Tsai Perng Jy
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Abstract
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Objectives: The respirator is said to be the last resort in terms of protection against many fumes, but is widely used in occupational settings. The surrogate test aerosols used for the certification of particulate respirators (PRs) include sodium chloride (NaCl), dioctyl phthalate (DOP), and paraffin oil. The purposes of this study were to evaluate the differences of pressure drop and particle filtration efficiency between certified single type and certified dual type PRs using NaCl, surrogate particulate, and welding fumes, real hazardous particle.
Methods: Fifteen commercial PR products (nine single-type and six dual-type filters) were selected. The NIOSH protocol was used with the TSI Model 8130 automated filter tester for NaCl test and well-designed welding fume chamber was used with a SIBATA filter tester and a manometer for welding fume test. The initial pressure drop and initial penetration, peak pressure drop and peak penetration, penetration pattern and pressure drop pattern, quality factor were compared.
Results: The count median diameter (CMD) and mass median diameter (MMD) for the NaCl aerosol were small compared with the measured welding fumes (CMD; 70-80 vs. 170-240 nm, MMD; 200-300 vs. 500-700 nm, respectively). The ANOVA test showed no significant difference between the initial pressure drop of the tested aerosols when single or dual filters were used (p = 0.42), whereas the pressure drop at peak penetration was significantly higher with welding fumes than for the NaCl aerosol (p = 0.04). Also, pressure drop increased much more rapidly in the welding fume test than the NaCl aerosol test. The high initial penetration and peak penetration occurred with the NaCl aerosol and not the welding fumes (p = 0.03, p < 0.001, respectively). Neutralized NaCl aerosols were less likely to be captured by electret PR filter media than the untreated electrically charged welding fumes. The calculated quality factors of tested PRs ranged between 0.07 and 0.65 and there was no significant difference between the tested aerosols and filter types (p = 0.09).
Conclusion: Taken together, these findings suggest that PRs, which are suitable for NaCl certification, could also be used in workplace settings where welding fumes occur, albeit with caution, because of rapid pressure drop increases. This study has gone some way towards enhancing our understanding of the penetration and pressure drop patterns of welding fume aerosols in the real workplace rather than for surrogate NaCl aerosols.
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KEYWORD
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penetration, pressure drop, respirator, sodium chloride, welding fumes
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