# Commission Delegated Regulation (EU) 2017/654 of 19 December 2016 supplementing Regulation (EU) 2016/1628 of the European Parliament and of the Council with regard to technical and general requirements relating to emission limits and type-approval for internal combustion engines for non-road mobile machinery, Division 3.4.4: NOx correction for humidity

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

All the NOx concentrations, including dilution air background concentrations, shall be corrected for intake-air humidity using equation (7-102) or (7-103):
(a) For compression-ignition engines
x NOxcor = x NOxuncor · (9,953 · x H2O + 0,832)
(7-102)
(b) For spark-ignition engines
x NOxcor = x NOxuncor · (18,840 · x H2O + 0,68094)
(7-103)
Where:
x NOxuncor uncorrected NOx molar concentration in the exhaust gas [μmol/mol]
x H2O amount of water in the intake air [mol/mol]

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Source: https://www.legislation.gov.uk/eur/2017/654/annex/VII/division/3/division/3.4/division/3.4.4 (the official version)
Page: https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-3/division-3.4/division-3.4.4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.