Application of an Elemental Carbon Analyser to the Measurement of Particulate Levels from Diesel Vehicles

Research has found that a new American instrument used to measure particulate levels from diesel vehicle exhaust is suitable for use in Australian coal mines.

Diesel vehicles in the underground mining industry offer greater flexibility (and therefore greater productivity) than standard electric vehicles. However, concerns have arisen over the potential for diesel exhaust and particulates to impact on the health of mine employees.

Historically, Bosch smoke meters have been the sole means of measuring soot levels in the exhaust of diesel engines used in the mining industry. These measurements were normally made during the approval of an engine package and no further routine monitoring was performed. While the Bosch smoke meter is easy to use, it only provides relative data and bears no relationship to ambient monitoring of employee exposure.

Rupprecht & Patashnick Co Inc (R&P) has developed a measurement technique based on elemental and total carbon, called Series 5100. This instrument was developed for use by vehicle manufacturers in the USA concerned with Environmental Protection Agency requirements that "over the road" vehicles produce less diesel particulate.

Project Objectives

The project had three key objectives, to:

• Validate an R&P Series 5100 diesel particulate measurement system against a standard elemental carbon method (NIOSH Method 5040)
• Establish the suitability of the instrument for the analysis of diesel particulate in the raw exhaust of underground diesel vehicles
• Determine the range of dust particulate levels in the exhaust of as many in-service mine vehicles as possible and establish those parameters that cause variations in dust particulate levels in the exhaust of the same engine type.

Findings

Initial testing involved the use of an "over the road" 4WD Toyota Landcruiser as the emission source and simultaneous samples were collected for validation using NIOSH Method 5040 at the University of Sydney. Further laboratory familarisation exercises were conducted until an acceptable level of competence was achieved.

These laboratory trials demonstrated the difficulties in modifying a laboratory-based instrument to a mine site environment and considerable time was consumed in ensuring that the instrument would withstand the rigors of the tasks proposed. This evaluation resulted in several refinements to the project work plan.

The research found:

• That the R&P Series 5100 diesel particulate analyser has the potential to control the output of particulate from diesel vehicles. Routine exhaust monitoring via mobile laboratories (similar to that currently used for gas analysis) may be effective in controlling employee exposures.
• Reasonable agreement at low diesel particulate concentrations, however, technical issues limited comparisons at higher concentrations of diesel particulate.
• Each vehicle engine type may have a normal output range and extreme variations from that range are usually due to mechanical fault or ineffective maintenance.
• The instrument has the potential to assist mine management in the selection of low emission equipment, thereby increasing operational flexibility and potentially reducing overall emission levels.
• The instrument has the potential to evaluate new control technologies in situ with minimal disruption to operations.
• More data is required before its application to "type testing" (approvals) can be evaluated.
• Concerns expressed that the introduction of flame protected 4WD vehicles would increase the level of diesel particulate in the mine atmosphere appear to be unfounded. Reductions of 70 percent to 90 percent per engine may be possible, thereby reducing overall general airbody diesel particulate levels.

Where To From Here

Further research and development is required before the R&P 5100 (or some other similar device) could be used in a routine manner within the Australian coal industry. Issues that need to be further evaluated or developed include:

• The incorporation of the R&P 5100 into a mobile laboratory, possibly one of the three mobile gas laboratories in New South Wales (BHP Environmental Health Laboratory, ACIRL Newcastle, Department of Mineral Resources)
• The relationship between dust particulates measured by the R&P 5100 and maintenance parameters
• The level of expensive retrofitted control technologies required to achieve acceptable dust particulate levels
• The relationship between exhaust dust particulate concentration, ventilation and employee exposure.