The technology behind reduced diesel emissions

You may have noticed some new labels on the diesel pumps at filling stations. Ultra Low sulphur diesel fuel is required for diesel vehicles produced after January 1, 2007 and this Ultra Low sulphur diesel has now made it though the supply system and is available at the pumps. Ultra Low sulphur diesel has less than 15 parts per million (ppm) sulphur content, compared to the maximum 500 ppm sulphur in regular low sulphur diesel fuel. Why do we need it? - to reduce the particulates in diesel engine exhaust.

When you hear about diesel particulates, you probably think about the black smoke you see shooting out the exhaust pipe as a diesel vehicle pulls away from a stop. Yes, those are particulates but much of what we see is large soot particulates that quickly fall to the ground. Most of the large particulates have been eliminated by the improvements in diesel fuel injection systems, but ultra fine particles (less than .1 micron in diameter) make up about 80-95% of diesel exhaust soot and that is what the new diesel emission systems are designed to control. The sulphur in diesel fuel doesn't create the particulates. Instead, ultra low sulphur fuel is needed to prevent damaging the exhaust converters and particulate filters that will prevent the particulates from entering the atmosphere.

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