Carbon Monoxide Index Monitoring System in an Underground Coal Mine

Experiments at the Somerset mine, Colo., under an agreement between US. Steel Corp. and the US. Bureau of Mines are described. A test was made of the tube bundle method of mine air sampling which was developed for European longwall mines; some 300,000 running feet of tubing provided continuous monitoring at 38 locations. Carbon monoxide concentrations were obtained with standard deviations of less than 1 ppm and oxygen concentrations with standard deviations of less than 0.2%. A base level of CO index (ppm CO evolved per percent 0, removed) was determined to be zero to 20 through most of the passageways of the mine. However, in one working section where the coal was initially hot (about 180°F within a pillar) the CO index was demonstrably higher, 120 trending upward to about 60 when smoke appeared and the section was sealed. The data are discussed in terms of laboratory experiments on CO evolution from coals.