The study, sponsored by Coal Partnership (BCOA, UMWA and NIOSH), was carried out during February and May 2002.
NIOSH researcher Aleksandar Bugarski, who presented a paper on the study at the Control Technologies for Diesel Vehicles in Underground Coal Mines workshop in Louisville, said tests carried out at the mine were executed as tailpipe emissions and isolated zone measurements.
The objective of the study was to investigate the effects of engine fuelling rate, size of torque converter and other engine/vehicle parameters on PM and gaseous emissions from the vehicles operated at high elevations.
It also looked at a short term evaluation of three diesel particulate matter filtration systems including the Wagner water scrubbers disposable filter elements from Donaldson and Baldwin; DST system with disposable filter element; and NETT Pt catalyzed filter.
Test outcomes concluded the maximum fuelling rate for the CAT 3306 PCNA engine as set by authorized Caterpillar service was found to be excessively high and resulted in an engine PM emissions significantly higher than that obtained by MSHA during sea level certification tests.
“The PM emissions from properly tuned vehicles were substantially lower than those obtained during MSHA certification,” Bugarski said in his presentation.
Vehicles adjusted to manufacture specifications and with a water scrubber and paper filter measured PM emissions of 2.5g/hr, above the compliance level.
“The testing resulted in the modifications of the certain components of the filtration systems including water separator and water level limit hole in the water scrubber. These modifications extended significantly filter life and improved efficiency of the systems,” he said.
The different filtration devices used came out with significantly diverse. The Donaldson “Blue” and DST PAAS M30 filter elements were found to remove diesel particulate matter measured as total carbon in excess of 95%. The other tested filters gave significantly lower reductions.
“After several minutes of operating vehicles retrofitted with diesel particulate filter with platinum based catalyst over test cycle, the concentrations of nitrogen dioxide in isolated zone exceeded ceiling levels of 5ppm,” he said.
“These tests show there is a potential for introduction of secondary health hazard with implementation of control technologies.”