# 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 3.5.2: Dry-to-wet concentration conversion

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

Parameters of this point are obtained from the results of the chemical balance calculated in point 3.4.3. The following relation exists between gas molar concentrations in the measured flow x gasdry and x gas [mol/mol] expressed on a dry and wet basis respectively [equations (7-109) and (7-110)]:
x gasdry = x gas 1 − x H2O
(7-109)
x gas = x gasdry 1 + x H2Odry
(7-110)
where:
x H2O molar fraction of water in the measured flow on a wet basis [mol/mol]
x H2Odry molar fraction of water in the measured flow on a dry basis [mol/mol]
For gaseous emissions a removed water correction shall be performed for the generic concentration x [mol/mol] by means of equation (7-111):
x = x emission meas 1 − x H2Oexh 1 − x H2O emission meas
(7-111)
Where:
x [emission]meas molar fraction of emission in the measured flow at measurement location [mol/mol]
x H2O[emission]meas amount of water in the measured flow at the concentration measurement [mol/mol]
x H2Oexh amount of water at the flowmeter [mol/mol]

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Source: https://www.legislation.gov.uk/eur/2017/654/annex/VII/division/3/division/3.5/division/3.5.2 (the official version)
Page: https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-3/division-3.5/division-3.5.2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.