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Rapid (grab) sampling during full-scale explosions--microscopic and analytical evaluation.

Conti RS; Zlochower IA; Sapko MJ
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9192, 1988 Jan; :1-17
The Bureau of Mines has developed a system using a high-speed electropneumatic mechanism for the rapid (grab) sampling of dusts and gases during an explosion. The sampling system consists of an aluminum housing that incorporates two 30-cm3 pre-evacuated glass vials with rubber septums. Upon actuation, the sampling probe needle is driven through the septum with a pressurized air pulse, filling the tube with gas and dust from the mine explosion. After a predetermined time, the sampling probe needle is retracted by a second high-pressure air pulse to its normal (quiescent) state, allowing the sampling tube to reseal. The onset and the duration of sampling are independently variable and controlled by a time-delay relay package. This technique enables the monitoring of pyrolysis-charring in coal particles and the generation and combustion of the pyrolysis vapors in both large- and small-scale explosions. The following results were obtained from full-scale dust explosion tests at the Bureau of Mines Lake Lynn Laboratory: (1) gas sampling of the leading edge of the flame front shows the large concentration changes, characteristic of the flame front; (2) gas samples taken entirely in the flame zone consist of pyrolysis and combustion products with very low residual oxygen; and (3) the particles collected in the flame zone show signs of extensive pyrolysis and charring.
Mining-industry; Mine-disasters; Mine-fires; Sampling-equipment; Sampling-methods; Coal-mining; Dust-explosions; Combustion-products
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IH; Report of Investigations
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NIOSH Division
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Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9192
Page last reviewed: November 19, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division