# Commission Regulation (EC) No 692/2008 of 18 July 2008 implementing and amending Regulation (EC) No 715/2007 of the European Parliament and of the Council on type-approval of motor vehicles with respect to emissions from light passenger and commercial vehicles (Euro 5 and Euro 6) and on access to vehicle repair and maintenance information (Text with EEA relevance), Division 3.8

Extent: E+W+S+N.I.

The second subparagraph of paragraph 1.3 of Appendix 8 to Annex 4 shall be understood as:
‘ … The dilution factor is calculated as follows:
For each reference fuel, except hydrogen
DF = X C CO2 + C HC + C CO × 10 − 4
For a fuel of composition CxHyOz, the general formula is:
X = 100 x x + y 2 + 3,76 × x + y 4 − z 2
In particular for H2NG, the formula is:
X = 65,4 × A 4,922A + 195,84
For hydrogen, the dilution factor is calculated as follows:
DF = X C H2O − C H2O − DA + C H2 × 10 − 4
For the reference fuels contained in Annex IX, the values of “ X ” are as follows:
Fuel
X
Petrol (E5)
13,4
Petrol (E10)
13,4
Diesel (B5)
13,5
Diesel (B7)
13,5
LPG
11,9
NG/biomethane
9,5
Ethanol (E85)
12,5
Ethanol (E75)
12,7
In these equations:
C CO2 concentration of CO 2 in the diluted exhaust gas contained in the sampling bag, expressed in per cent volume,
C HC concentration of HC in the diluted exhaust gas contained in the sampling bag, expressed in ppm carbon equivalent,
C CO concentration of CO in the diluted exhaust gas contained in the sampling bag, expressed in ppm,
C H2O concentration of H 2 O in the diluted exhaust gas contained in the sampling bag, expressed in per cent volume,
C H2O-DA concentration of H 2 O in the air used for dilution, expressed in per cent volume,
C H2 concentration of hydrogen in the diluted exhaust gas contained in the sampling bag, expressed in ppm,
A quantity of NG/biomethane within the H2NG mixture, expressed in per cent volume ’ .

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Source: https://www.legislation.gov.uk/eur/2008/692/annex/III/division/3/division/3.8 (the official version)
Page: https://openlegislation.uk/eu-regulation-2008-692/annex-III/division-3/division-3.8
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.