Smoke test limit set
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• The Vehicle Inspectorate has set the limit for diesel exhaust smoke on the free acceleration test at 75 Hartridge units (K = 3.2m-1, 5.2 Bosch, 530gm2) which, it says, equates to the current test. This is the first objective exhaust testing for HGVs and PCVs and should be included in the annual test from 1 July 1992.
Strict emission limits come in to force in 1995 and it is not yet clear if the free acceleration/opacity meter Lest will be able to satisfactorily check vehicles in service. While the VI admits that opacity meters are only the first step, it expects them to be in use past 1995.
However, if no reliable correlation can he found between the 1995 limits and the free acceleration smoke test more sophisticated equipment, which could include a rolling road, will have to be installed in Lest stations.
The VI has published the specification for the smoke meters and is asking the suppliers to suggest ways of taking measurements given the variety of tailpipe positions.