Exhaust gas opacity measurements

Exhaust gas opacity is a result of the presence of solid particles (mostly soot – black smoke), hydrocarbons (blue smoke) and water vapour (white smoke). At a soot content of 100-300 mg/m3 the exhaust gas opacity is noticeable. Black smoke appears at concentrations of approx. 500 mg/m3. An increase in exhaust gas opacity is usually accompanied by an increase in the emission of other harmful exhaust gas components (CO2, CO, HC, NOx).
Exhaust smoke opacity measurement is conducted by using an adsorption opacimeter, which makes use of phenomena relating to the absorption of visible radiation (light) passing through the gas.


  • Absorption opacimeter – AVL Opacimeter 439



  • UNECE Regulation No. 24
Document No. Title/Description
Regulamin nr 24 EKG ONZ/ UN ECE Regulation No. 24 / Regelung Nr. 24 UN/ ECE United Nations Economic Commission for Europe (UNECE) Regulation No. 24 – Uniform provisions concerning: The Approval of Compression Ignition (C.I.) Engines with Regard to the Emission of Visible Pollutants