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| Titel: |
Respirator Leak Detection by Ultrafine Aerosols: A Predictive Model and Experimental Study |
| Auteur: |
Liu, Benjamin Y. H. Lee, Jae-Keun Mullins, Haskelle Danisch, Susan G. |
| Verschenen in: |
Aerosol science and technology |
| Paginering: | Jaargang 19 (1993) nr. 1 pagina's 15-26 |
| Jaar: |
1993 |
| Inhoud: |
The leak performance of half-mask, maintenance-free respirators was studied theoretically and experimentally. A predictive model for the theoretical protection factor and leakage flow has been developed that uses the equation of particle conservation inside and outside the respirator. An experimental study was conducted using NaCl particles of 10 nm in diameter and a condensation nucleus counter as the particle detector. A respirator fitted with controlled leak holes of 20-3000 μm in diameter was tested at steady flow rates of 10, 32, and 100 L/min. Results showed that the aerosol penetration into a respirator was strongly influenced by the filter efficiency, leak hole size, and flow rate through the respirator. The results are in good agreement with theory, but some discrepancy has been noted at lower flow rates and smaller leak hole sizes. For the dust/mist respirators, the experimental protection factor for ultrafine 0.01-μm NaCl particles ranged from 3145 to as low as 3. For the high efficiency dust/mist/fume/radionuclide respirator, a protection factor as high as 4.1 × 109 was measured on the ultrafine aerosol. For all respirators, the protection factors decreased rapidly with increasing leak hole size and increased as flow rate decreased. The result of the study shows that with ultrafine aerosols, the particle penetration through the respirator filter can be reduced to a small, and in some instances, negligible value. The resulting protection factor is then due almost entirely to aerosol penetration through the leak hole. The ultrafine aerosol test can thus be used to study the characteristics of the face seal leakage, without the complication of the aerosol penetration through the respirator filter. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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