This document specifies the measurement procedures and test cycles for the evaluation of smoke emissions from compression ignition engines using an opacimeter. The tests are carried out under steady-state and transient operation using tests cycles which are representative of a given application.

The smoke testing is conducted using opacimeter-type smoke meters which operate on the light extinction principle. The purpose of this document is to define the smoke test cycles and the methods used to measure the opacity and for the determination of the light absorption coefficient. It allows the use of either full-flow or partial-flow opacimeters and corrects for differences in rise time between the two types of opacimeters. Specifications of the apparatus for the measurement of opacity can be found in ISO 11614. The test procedures and measurement techniques described in this document are applicable to reciprocating internal combustion (RIC) engines in general. Annex D, Annex E, Annex F and Annex G each contains a test cycle that is relevant only for those specific applications listed in the first subclause of that annex. Where possible, the smoke test cycle described in the annex utilizes the engine and machine categories developed in ISO 81784.

For certain categories of non-road engines "at site" rather than "test bed" smoke test procedures can prove to be necessary. For engines used in machinery covered by additional requirements (e.g. occupational health and safety regulations), additional test conditions and special evaluation methods can apply.