Measurement of exhaust gas opacity with free acceleration (no load from idling up to cut-off speed). The level of concentration must not exceed(2) the following limit values of the coefficient of absorption:
- naturally aspirated diesel engines = 2,5 m-1,
- turbo-charged diesel engines = 3,0 m-1, or equivalent values where use in made of equipment of a type different from that complying with these requirements.
