NSW Dept of Primary Industries, Mine Safety Technical Services – November 2004

Methods for measuring Diesel Particulate Matter (DPM) from underground Mining Equipment

The project was funded by the Coal Services Health and Safety Trust, and run by the NSW Department of Mineral Resources (now incorporated into Department of Primary Industries). It aimed to find one or more methods for measuring diesel particulate matter (DPM) in the raw exhaust of diesel-powered mining equipment at underground coal mines. The method(s) were required to correlate reasonably well with the standard method for measuring DPM, and would be practical for use underground at mine sites by mine personnel.

The water scrubber on these machines was recognised from the start as a potential cause of problems.

A number of techniques and instruments were considered, and the project focussed on three laser light-scattering instruments, and a NIOSH pressure-drop method. The light-scattering instruments were found to require diluted and dried sample in order to cope with water in the raw exhaust – either before or after the water scrubber. The NIOSH sampling tubes were modified to handle the water. The testing included the Bosch smoke meter and the R&P Elemental Carbon Analyser, which have bothe been used extensively in mines in recent years.

The methods were first evaluated against the standard dilution tunnel method (using weighed filter papers) and other recognised methods. Tests were conducted using three engines operating on an engine dynamometer under tight control, using a single fuel. The tests involved steady-state conditions, and also steady state with accelerations.

Correlations between the instruments and the standard method varied. Difficulty was encountered with one light-scattering instrument, which was also much larger than the others. It was not included in the later trials.

The methods were refined in the light of the dynamometer tests. The dilution system for the light-scattering instruments was made much more precise. An improved sample pump for the NIOSH method made this a simpler method to use.