DIN 51402-1:1986-10

The method according to this standard is used for determination the blackening index of exhaust gases of heating installations fired by heating oil EL according to DIN 51603 part 1. For the determination a specified volume of the exhaust gas is forced through a filterpaper. This causes a blackening of the surface of the filter paper. The degree of blackening is measured either by a visual comparison with a test chart or by a photometric comparison with a reference curve.