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Performance of industrial mist collectors over time.

Authors
Boundy-M; Leith-D; Hands-D; Gressel-MG; Burroughs-GE
Source
Appl Occup Environ Hyg 2000 Dec; 15(12):928-935
NIOSHTIC No.
20020618
Abstract
Effective, economical control of metalworking fluid mists at the source is important, because exposure to these mists may cause adverse health effects. This study investigated performance changes over time for industrial collectors that removed metalworking fluid mist in the laboratory and in a transmission plant. Aerosizers were used to measure the efficiency of each stage in several multistage collectors as a function of mist droplet diameter, for up to one year of continuous operation. Metal-mesh, first-stage filters operated at low pressure drops and were effective at removing droplets larger than 3 to 5 microns in diameter. Some second-stage filters worked better than others. Both "65 percent" and "95 percent" cartridge filters failed after only a few weeks; their efficiencies decreased substantially over that time. Pocket filters and cylindrical cartridges used as second-stage filters also decreased in efficiency for submicron droplets. Whereas filters for solid particles load continuously to form a dust cake that increases efficiency, mist filters form no cake and load only to the point where collection equals drainage. As a mist filter loads, the interstitial gas velocity increases, so that efficiency decreases for small droplets that collect by diffusion. Although a third-stage 95 percent DOP filter showed important decreases in efficiency over time for submicron droplets, third-stage HEPA filters operated with efficiencies that consistently approaches 100 percent for droplets of all sizes, even after one year of operation. These results suggest that the performance of second-stage filters can be improved if they can be made to drain collected liquid more effectively. For high efficiency, mist collectors should use a HEPA filter as a final stage.
Keywords
Aerosol-particles; Air-quality-monitoring; Air-contamination; Air-quality-measurement; Filter-materials; Safety-measures; Oil-mists; Metalworking; Metalworking-industry; Metalworking-fluids
CODEN
AOEHE9
Publication Date
20001201
Document Type
Journal Article
Fiscal Year
2001
NTIS Accession No.
NTIS Price
Issue of Publication
12
ISSN
1047-322X
NIOSH Division
DART
Source Name
Applied Occupational and Environmental Hygiene
State
NC; MI; OH; IL
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