Developed by Rupprecht & Patashnick (R&P), the PDM provides a continuous reading of respirable dust exposure to which a miner is exposed during a working shift.

The new development from R&P is of particular importance in view of new dust monitoring rules being considered by MSHA.

“The final determination of how the PDM may be used in the context of future regulations is uncertain at present - we should know a lot more by the end of 2004. I can state with certainty, however, that the unit enjoys very strong interest and support from labor, industry and government,” said R&P business development director Erich Rupprecht.

R&P said the PDM holds the potential for increasing the amount and quality of personal exposure information available to miners and mine operators during the course of a worker’s shift. Statistics generated by the monitor can be used on a routine basis to help ensure that no miner is exposed to dust concentrations higher than the legal limit value.

Results from mine tests during June to August this year in Pennsylvania, West Virginia, Utah and Alabama show the data availability rate of the personal dust monitor was 93%, with seven data sets lost out of 115 runs. Based upon the statistical t-test criteria prescribed in the test protocol, the PDM generated the same results as the reference samplers at all four mines.

Following delivery of the next production run of monitors in early 2004, NIOSH and MSHA expect to carry out an expanded test protocol to gain information about the best way to utilize the continuous dust exposure data generated by the device.

Currently there are six prototypes which were used by NIOSH during the underground trials. Three of the development prototype units will continue to be used in some additional mine trials during the coming months until the commercial product is delivered, while the other three are being used by R&P as laboratory test platforms.

The first of the new generation of PDMs will be delivered to NIOSH early in the second quarter of 2004, with additional quantities to be supplied to other government agencies and commercial customers very shortly thereafter.

R&P’s New York head office anticipated the PDM would be available in Australia through distributor Ecotech about mid-year for trial or resale.

The PDM takes the place of the cap lamp battery currently attached to a miner’s belt. It contains an updated power supply for the miner’s cap lamp and adds the continuous mass measurement functions in a size and weight similar to the battery pack miners currently wear.

The device uses an extreme miniaturization of R&P's TEOM mass measurement technology, as well as sample transport and conditioning methods developed by R&P for the representative assessment of suspended particle samples.

A filter-based mass reading of the particulate matter concentration in the mine atmosphere is generated which is equivalent to the current integrated filter methods.

Miners and mine operators receive information during a miner's shift, allowing for engineering and administrative controls to be implemented to help ensure that no miner is subject to an exposure that is higher than the legal limit value.

The mass measurements generated by the PDM are NIST traceable, and are a direct (as opposed to surrogate) measurement of the particle mass collected on a filter.