An emissions assisted maintenance procedure (EAMP) was developed to help mine operators implement the MSHA regulation that requires emissions testing of diesel-powered mine equipment. The EAMP provides mine operators with a sound method that meets all of the requirements of the new regulation. It also provides a framework in which mine operators can develop a procedure that includes measurement of additional emission. Detailed instructions for implementing the EAMP will be provided in an a separate publication entitled, "EAMP Training Manual."

All the significant factors that affect emissions were considered before a procedure was developed to utilize emissions to identify a need for maintenance. The effects on engine emissions of fuel, ambient conditions, engine wear, engine design, engine speed, load, and engine faults were all examined as part of the EAMP development. The EAMP accurately identifies engines in need of maintenance by controlling the variables that could otherwise lead to erroneous test results. Previously developed methods to perform on-site emission tests were also reviewed to extract those components most needed in an underground environment.

The EAMP proved to be effective in the laboratory and in the field. CO and CO2 measurements were used to identify clean, dirty, and clogged air filter conditions at greater than 95% full load at two different speeds. By the c²_red test, no significant disagreement was detected between the portable analyzer measurements and the laboratory-grade analyzer measurements. In the field, the procedure indicated differences in emission concentrations between some of the similar engine models. These differences indicated that there was a need for further inspection and possible maintenance. Tests repeated on different days indicated that the torque converter stall loading method could be repeated such that the CO2 concentration varied less than 5%. Furthermore, the engine loading and sampling methods were straightforward and easily performed by mine maintenance personnel. Based upon the data collected, the development of the EAMP training manual should not require additional field research.

There are still improvements that could be made to optimize the EAMP. The portable analyzer and PC combination, used in the field, proved to be somewhat bulky. A hand-held analyzer with the accuracy of the Ecom-AC and the data graphing and recording capabilities of the laptop PC would be ideal and more readily accepted by mine maintenance personnel.

No matter what instrument is ultimately chosen, a baseline emission database should be established to implement the EAMP most equitably. It was shown that engine models produce characteristic normal, or baseline emissions. A database, consisting of baseline full-load CO and CO2 concentrations for specific engine models, would ensure that all mine operators would expect similar emissions from similar engines. Until this database is established, it will be the mine operator's responsibility to use new or properly operating engines to determine baseline emissions for each engine model. To make maintenance decisions, mine operators will have to rely upon comparisons between their weekly test results and their self-determined baseline emissions. A basic guide on how to establish reasonable baseline emissions and how to make judgments based on these baselines will be provided in the EAMP training manual. No extended field research has been conducted to conclude whether or not the EAMP is effective in identifying specific engine faults, however. Currently the EAMP will only determine whether or not there is a need for engine maintenance. Depending upon further research, a supplement to the EAMP training manual may provide information about identifying specific engine faults with the EAMP. This supplement also may provide an initial database of baseline emissions. MSHA may generate this database during its equipment approval process. Performing the EAMP on equipment before the equipment leaves the manufacturer may also be a practical means of generating baseline emission data.

The EAMP will still be useful without an emission database and without the conclusions of the specific fault identifying research. The EAMP can identify equipment that exceeds the MSHA CO limit of 2500 ppm, and it can detect trends and changes in emissions that indicate a need for maintenance. The EAMP will provide mine operators with a valuable tool that can help minimize worker exposure to diesel emissions, and it can also help increase production by identifying those engines that may otherwise break down unexpectedly. This procedure will only become more valuable as supplemental information is generated.