• +49 7131 200064
  • info@imgmbh.de
  • Competent consulting
  • +49 7131 200064
  • info@imgmbh.de
  • Competent consulting



In addition to various gases that are harmful to health, the exhaust gas from diesel engines also contains soot particles, which must be measured or checked in accordance with the legal regulation TRGS 554.

TRGS 554 - Exhaust gases from diesel engines

Excerpts regarding blackening number

  • Applies to activities in work areas (fully or partially enclosed spaces) where exhaust gases from diesel engines may be present in the air at workplaces.
  • Only diesel trucks equipped with a diesel particulate filter (DPF) system that ensures a permanent separation rate of more than 90% may be used in these work areas.
  • Exhaust emissions from diesel engines used by the employer in fully or partially enclosed work areas shall be monitored in accordance with the provisions of Appendix 3.

TRGS 554 Annex 3 - Maintenance concept, exhaust gas measurement

  • The engine condition must be determined by an authorized technician after 1500 operating hours at the latest, but at least once a year, by taking measurements in the undiluted exhaust gas of the diesel engine in reproducible operating conditions, e.g. upper idle speed to determine the blackening number.
  • In order to be able to evaluate the soot emitted, a so-called blackening index was introduced.
  • The blackening index is a measure of the soot emission of a diesel engine, measured with a filter-based measuring instrument. The soot contained in the exhaust gas blackens the filter paper. The blackening number is determined by measuring the optical reflection of the blackened filter in comparison with a clean filter and is expressed as a blackening (soot) number.

A inspection certificate serves as proof that the blackening number measurement has been carried out. This certificate must be completed, signed by the authorized technician and handed over to the user.

Why is it important to determine the soot particles?

Soot occurs as an undesirable product during combustion processes and contains oily products from incomplete combustion. Soot consists primarily of small particles that, because of their size, can penetrate into a person's lungs. In medical studies, soot has been shown to cause cancer.

SUMMARY - Exhaust gas measurement on forklift trucks with diesel engine:

  • Exhaust gas measurement to be carried out annually or at the latest after 1500 operating hours in accordance with the maintenance concept.
  • The exhaust gas measurement can only be carried out after engine maintenance.
  • Creation of inspection certificate

Exhaust gas analysers for blackening (soot) number measurement on forklift trucks with diesel engine