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This paper addresses the subject of engines for non coal non-gassy mine applications and presents a proposal for worldwide harmonized emission standards. Diesel-powered equipment is extensively utilized in underground hard rock and coal mines. This is due, to a great extent, to the efficiency and safety characteristics of the Diesel engine. Regulations are in place addressing the emission quality of these engines. Furthermore, sufficient mine ventilation must be provided in order to ensure that pollutant levels in the working environment don't exceed permissible levels. Historically, Diesel engines featuring Indirect Injection (IDI) combustion systems have been preferred for underground mining operation due to their cleaner exhaust gas characteristics. The ever increasing stringency of the emission requirements applicable to on-highway trucks has resulted in Direct Injected (DI) Diesel engines with emission characteristics equal to, or in some areas, better than IDI engines.

The development of European emission regulations for automotive heavy-duty Diesel engines began in the mid 1970s; the latest modifications to test procedures and standards have been in place since 1988. Presently, the emphasis of the European regulatory activities is in the areas of increasing the stringency of the gaseous standards and developing particulate standards. For non-automotive industrial engines, test procedures and standards are presently under consideration. Implementation of these requirements is anticipated in a two-stage approach beginning in the mid 1990s. This paper provides an overview of the present and future European exhaust emission requirements.

A correlation program was established between heavy-duty engine transient test facilities in order to determine emission variabilities within and among laboratories. Significant differences between the laboratories observed for all emission components were smaller compared to data reported previously. For gaseous emissions among-lab standard deviation was significantly, for particulates only slightly higher than within-lab standard deviation. Two groups of laboratories were found that correlate rather well within the respective group. Normalizing the standard deviations to 1991 emission regulations showed that oxides of nitrogen and hydrocarbon variabilities were about 16 %, particulate variability about 45 % of the regulated emission values. Therefore, particulate measurement has to be improved considerably. Cycle work was found to influence among-lab variability of all components.