Abstract
The Federal Mine Safety and Health Act of 1977 requires mine operators to sample mine atmospheres periodically to determine compliance with the federal respirable dust exposure standard. To do so, mine operators use gravimetric samplers that are approved by the Mine Safety and Health Administration, Department of Labor. However, dust measurements by gravimetric methods are inherently delayed and are susceptible to tampering and accidental dislodgement of dust. A special Mine Safety and Health Administration Task Group recommended that the U.S. Bureau of Mines develop a fixed-site monitor that would provide continuous information to the miner and mine operator regarding dust levels and the status of compliance with the applicable respirable dust standard. In response to that recommendation, the bureau initiated a multicomponent research program to develop suitable technology for a continuous respirable coal mine dust monitor. As part of that program, the bureau funded the development of a novel dust measurement technology called resonant filter membrane mass monitoring. The technology relates changes in the vibration frequency of a taut circular dust collection filter membrane to the mass of dust collected on the filter. This article reviews the principle of operation, describes prototype hardware, discusses potential advantages and disadvantages, and presents test results to date. While this technology offers several advantages, especially the direct measurement of dust mass, early tests of the prototypes identified several problems that must be solved before a practical, reliable, fieldworthy device can be produced.