Loading and filtration characteristics of filtering facepieces

Chih Chieh Chen, Matti Lehtimäki, Klaus Willeke

Research output: Contribution to journalArticleScientificpeer-review

41 Citations (Scopus)

Abstract

Most filtering facepieces used today are made of electret material (material with significant electrical charges on the filter fibers). Because of the addition of this electrical removal force, the filtration efficiency can be significantly increased without increasing the air pressure drop inside the respirator; pressure drop is closely related to physiological load. However, the removal by electrical forces is reduced in time, as aerosols deposit on the filter fibers. We have studied the contribution of this electrical removal and its change in time as a function of aerosol loading. To prove the change in aerosol penetration is due to the reduction of electrical force, the electrical charges were removed from new facepieces by the application of appropriate chemicals.The dust-mist filtering facepieces tested have similar fiber diameters and packing densities, as determined by scanning electron microscopy and pressure drop data. At a face velocity of 10 cm/s (corresponding to 100 L/min through a complete filtering facepiece) and an aerosol size of 0.16 μm, electrical force removal accounts for 69% of the total filtration for the respirator found to have the best filter quality but only 25% for the respirator (from a different manufacturer) found to have the worst filter quality. Our experimental data show that the removal efficiency of these facepieces is reduced in time by as much as this amount. However, under normal wear conditions, the total aerosol particle load is not as high as shown and the filtering facepieces are likely to be discarded before the fiber charges (i.e., the electrostatic attractions) are significantly diminished.

Original languageEnglish
Pages (from-to)51 - 60
Number of pages10
JournalAmerican Industrial Hygiene Association Journal
Volume54
Issue number2
DOIs
Publication statusPublished - 1993
MoE publication typeA1 Journal article-refereed

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Aerosols
Mechanical Ventilators
Air Pressure
Pressure
Dust
Static Electricity
Electron Scanning Microscopy

Cite this

Chen, Chih Chieh ; Lehtimäki, Matti ; Willeke, Klaus. / Loading and filtration characteristics of filtering facepieces. In: American Industrial Hygiene Association Journal. 1993 ; Vol. 54, No. 2. pp. 51 - 60.
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abstract = "Most filtering facepieces used today are made of electret material (material with significant electrical charges on the filter fibers). Because of the addition of this electrical removal force, the filtration efficiency can be significantly increased without increasing the air pressure drop inside the respirator; pressure drop is closely related to physiological load. However, the removal by electrical forces is reduced in time, as aerosols deposit on the filter fibers. We have studied the contribution of this electrical removal and its change in time as a function of aerosol loading. To prove the change in aerosol penetration is due to the reduction of electrical force, the electrical charges were removed from new facepieces by the application of appropriate chemicals.The dust-mist filtering facepieces tested have similar fiber diameters and packing densities, as determined by scanning electron microscopy and pressure drop data. At a face velocity of 10 cm/s (corresponding to 100 L/min through a complete filtering facepiece) and an aerosol size of 0.16 μm, electrical force removal accounts for 69{\%} of the total filtration for the respirator found to have the best filter quality but only 25{\%} for the respirator (from a different manufacturer) found to have the worst filter quality. Our experimental data show that the removal efficiency of these facepieces is reduced in time by as much as this amount. However, under normal wear conditions, the total aerosol particle load is not as high as shown and the filtering facepieces are likely to be discarded before the fiber charges (i.e., the electrostatic attractions) are significantly diminished.",
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Loading and filtration characteristics of filtering facepieces. / Chen, Chih Chieh; Lehtimäki, Matti; Willeke, Klaus.

In: American Industrial Hygiene Association Journal, Vol. 54, No. 2, 1993, p. 51 - 60.

Research output: Contribution to journalArticleScientificpeer-review

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