A Novel Test Stand for the Generation of Diesel Particulate Matter

Abstract

Todays industry uses a wide variety of diesel engines. Especially in mineral salt and potash mining, they have become the most important production factor since their introduction in the early 60s. I ARC classified diesel particulate matter (DPM) as probably carcinogenic (IARC, 1989). NIOSH recommended that DPM be regarded as possibly carcinogenic (NIOSH, 1988). In Germany, discussions about possible health hazards due to DPM exposure resulted in 1990 in its official classification as cancerogenic (MAK Werte, 1990). The respective limit value (Technische Richtkonzentration (TRK)) was published one year later (MAK Werte, 1991). Several problems caused by DPM have not been solved yet. Internationally for instance, relatively few quantitative exposure data are available. Moreover, the inherent characteristics of the cancerogenic effect are obviously still under discussion among medical experts although an agreement about the general cancerogenic properties of DPM seems to exist. In addition, the measuring technique to be referred to for DPM determination (sampling and analytical steps) is internationally still inconsistent. However, to measure the particulate proportion of diesel exhaust, i.e. especially (EC) is undisputed. To separate this substance from coarse dust, sampling of the respirable dust fraction according to EN 481 (EN 481, 1993) is necessary. Even though the German TRK value is still based on the so-called total (TC) concept (carbon dioxide in the respirable dust fraction due to combustion determined by coulometric measurement and recalculation as carbon), a procedure to determine elementary carbon was developed in Germany and put into practice. The introduction of specific limit values on the basis of elementary carbon is scheduled to take place in the autumn of 1996. (See procedure description by Dahmann et al. (1996) and in ZH 1/120.44 (1995).) This method also requires respirable dust sampling on quartz fibre filters. Using inert gas, the filters are subjected to desorption/decomposition under high temperatures. The compounds to be desorbed (so-called organic (OC)) are removed from elementary carbon and also determined after catalytic oxidation to CO2. As usual, the remaining elementary carbon is determined by oxygen combustion and subsequent coulometric titration. Since the introduction of this method, a great number of