Dust monitor helps fight black lung

Citation

(1998), "Dust monitor helps fight black lung", Sensor Review, Vol. 18 No. 4. https://doi.org/10.1108/sr.1998.08718daf.001

Dust monitor helps fight black lung

Dust monitor helps fight black lung

Keywords Environmental monitoring, Health and Safety

The inaccurate measurement of unsafe coal dust has exacted a heavy price on miners in the form of black lung disease. The National Institute for Occupation Safety and Health (NIOSH) in Washington, DC, has sponsored the development of a machine-mounted, continuous respirable dust monitor to improve the measurement of dust levels and reduce the occurrence of the dangerous respiratory disorder.

The new dust monitor is being designed by Rupprecht and Patashnick Co. in Albany, New York, which invented a proven tapered-element oscillation microbalance (TEOM) sensing technology. With this technology, samples of mine air are drawn into a metal or glass tube. While the wide end of the tube is solidly anchored, the narrow end is fitted with a replaceable filter and is permitted to vibrate. As the f'ilter collects dust, its increase in mass causes the tampered element to vibrate more slowly across the path of light between a light-emitting diode and a phototransistor. The latter generates electric signals according to the amount of light it receives. An onboard computer measures the change in frequency of these signals to calculate how much dust was collected on the filter.

Because the monitor was designed for aboveground work, the challenge for Rupprecht and Patashnick engineers and their NIOSH counterparts was to ruggedize the device so it would work when mounted on coal-cutting machines used in the gritty environment of the coal mines. The monitor also had to continue operating, even when buried under a few tons of coal.

"We installed the TEOM technology in a steel casing consisting of a 3Ž8in top plate, connected to a 1Ž4in bottom plate, which is attached to a coal-cutting machine by 3Ž8in steel bolts", said Dave Hassel, a mechanical engineer and senior staff engineer at Rupprecht and Patashnick. Hassel and his colleagues housed the TEOM electronics in a 125lb explosion-proof box made up of 1in thick walls of cast aluminium. "A 1Ž2in thick glass portal enables the operator to view the computer screen", Hassel said. A shock-isolation suspension and a vibration-isolation suspension within the box ensure accurate measurement despite vibration from the coal-cutting machine.

Models of the new monitor are being tested successfully on two different machines in four separate coal mines. The next step is to build ten production models that can be tested in mines across the USA. "We should be in a position to sell units commercially in the next six months", Hassel said. "After that, we will be working on making a hand-held version ... to eliminate the possibility of black lung".