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Continuous wave laser ignition thresholds of coal dust clouds.

Authors
Dubaniewicz-TH; Cashdollar-KL; Green-GM
Source
J Laser Appl 2003 Aug; 15(3):184-191
NIOSHTIC No.
20023572
Abstract
Laser-based instruments are used in areas where coal dust ignition presents a safety hazard. The National Institute for Occupational Safety and Health's Pittsburgh Research Laboratory is conducting a study to help determine when an optical beam may be considered a potential ignition source in underground coal mines or coal storage facilities. Researchers conducted experiments to determine threshold igniting powers for Pittsburgh Seam bituminous coal dust clouds using an 803-nm continuous wave laser. For fine-sized coal dust dispersed in air, concentrations ranging from 600 to 2,000 g/m3 were the most easily ignited. A heated layer of coal dust that deposited on the fiber tip during dispersion ignited the dust clouds. Minimum observed igniting powers for laser beams delivered by 200-, 400-, and 800-micrometer core fiber-optic cables and directed into coal dust clouds were 2.0, 3.0, and 5.0 W, respectively. Threshold igniting power was proportional to beam diameter, and threshold igniting power density decreased with larger fiber diameters. Ignition delay times averaged 0.6 sec and did not vary significantly with laser power under initially turbulent test conditions and with flammable targets. Comparisons are made with the results of other researchers.
Keywords
Lasers; Coal-dust; Underground-mining; Coal-mining; Fire-hazards; Explosion; Ignition-sources; Author Keywords: laser ignition; coal dust ignition; nonbeam hazard
Contact
NIOSH Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
CODEN
JLAPEN
Publication Date
20030801
Document Type
Journal Article
Fiscal Year
2003
NTIS Accession No.
NTIS Price
Issue of Publication
3
ISSN
1042-346X
NIOSH Division
PRL
Priority Area
Research Tools and Approaches: Control Technology and Personal Protective Equipment
Source Name
Journal of Laser Applications
State
PA
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