The Sensidyne CDEM-1000 Coal Dust Explosibility Meter is a portable, handheld, easy-to-use instrument, which is designed to provide a direct indication of the potential explosibility of a coal and rock dust mixture in accordance with Title 30, Code of Federal Regulations, Part 75.403.
The CDEM was tested and validated at the NIOSH Office of Mine Safety and Health Research Laboratory in Pittsburgh. It has an MSHA approval
(18-A 110002-0) for use in underground coal mines. The CDEM-1000 meets the needs of mining operators and safety inspectors when following the coal dust sample collection guidelines as described in Bureau of Mines Information Circular I.C. 7113 or MSHA Handbook, Number PH-08-V-1.
Current regulations require the application of inert rock dust in all underground areas of a bituminous coal mine to mitigate the propagation of a coal dust explosion. The CDEM-1000 is intended to be used by mine operators, safety officials and regulators as a screening tool to help manage daily rock dusting operations and to help mitigate the explosion hazard potential by identifying inadequate rock dusting applications. The CDEM-1000 can also be used as an effective tool by mine operators to help determine a more efficient balance between coal dust and rock dust levels.
The operation of the CDEM-1000 is based on the difference in optical reflectance between the darker coal dust and the lighter inert rock dust in band samples taken from the mine surface. The mixture of coal dust and the lighter inert rock dust becomes lighter in color as the concentration of rock dust increases. The higher the concentration of rock dust, the lower the explosion potential of the coal dust mixture. The instrument is intended to be a "go", "no-go" device which displays a ***RED*** indication for insufficient rock dust levels and a ***GREEN*** indication when the minimum safe level of rock dust is reached. The CDEM-1000 sets the minimum safe level of rock dust at not less than 80 percent in the absence of methane and increases the minimum safe level of rock dust by 0.4 percent for each 0.1 percent of background methane at the sample site.