{
  "url": "https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-3/division-3.5/division-3.5.3",
  "json_url": "https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-3/division-3.5/division-3.5.3.json",
  "legislation": "eur/2017/654",
  "legislation_title": "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",
  "legislation_url": "https://openlegislation.uk/eu-regulation-2017-654",
  "path": "annex/VII/division/3/division/3.5/division/3.5.3",
  "kind": "division",
  "number": "3.5.3",
  "heading": "Exhaust gas molar flow rate",
  "text": "The flow rate of the raw exhaust gas can be directly measured or can be calculated based on the chemical balance of point 3.4.3. Calculation of raw exhaust gas molar flow rate is performed from measured intake air molar flow rate or fuel mass flow rate. The raw exhaust gas molar flow rate can be calculated from the sampled emissions, ṅexh , based on the measured intake air molar flow rate, ṅint , or the measured fuel mass flow rate, ṁfuel , and the values calculated using the chemical balance in point 3.4.3. It shall be solved for the chemical balance in point 3.4.3 at the same frequency that ṅint or ṁfuel is updated and recorded.\n(a) Crankcase flow rate. The raw exhaust gas flow can be calculated based on ṅint or ṁfuel only if at least one of the following is true about crankcase emission flow rate:\n(i) The test engine has a production emission-control system with a closed crankcase that routes crankcase flow back to the intake air, downstream of intake air flow meter;\n(ii) During emission testing open crankcase flow shall be routed to the exhaust gas according to point 6.10 of Annex VI;\n(iii) Open crankcase emissions and flow are measured and added brake-specific emission calculations;\n(iv) Using emission data or an engineering analysis, it can be demonstrated that neglecting the flow rate of open crankcase emissions does not adversely affect compliance with the applicable standards;\n(b) Molar flow rate calculation based on intake air.\nBased on ṅint , exhaust gas molar flow rate ṅexh [mol/s] shall be calculated by means of equation (7-112):\nṅ exh = ṅ int 1 + x int/exhdry − x raw/exhdry 1 + x H2Oexhdry\n(7-112)\nWhere:\nṅ exh raw exhaust gas molar flow rate from which emissions are measured [mol/s]\nṅ ind intake air molar flow rate including humidity in intake air [mol/s]\nx int/exhdry amount of intake air required to produce actual combustion products per mole of dry (raw or diluted) exhaust gas [mol/mol]\nx raw/exhdry amount of undiluted exhaust gas, without excess air, per mole of dry (raw or diluted) exhaust gas [mol/mol]\nx H2Oexhdry amount of water in exhaust gas per mole of dry exhaust gas [mol/mol]\n(c) Molar flow rate calculation based on fuel mass flow rate\nBased on ṁfuel, ṅexh [mol/s] shall be calculated as follows:\nWhen conducting laboratory testing this calculation may only be used for discrete-mode NRSC and RMC [equation (7-113)]:\nṅ exh = ṁ fuel × W C × 1 + X H 2 Oexhdry M c × X Ccombdry\n(7-113)\nWhere:\nṅ exh raw exhaust gas molar flow rate from which emissions are measured\nṁ fuel fuel flow rate including humidity in intake air [g/s]\nw C carbon mass fraction for the given fuel [g/g]\nx H2Oexhdry amount of H2O per dry mole of measured flow [mol/mol]\nM C molecular mass of carbon 12,0107 g/mol\nx Ccombdry amount of carbon from fuel in the exhaust gas per mole of dry exhaust gas [mol/mol]\n(d) Exhaust gas molar flow rate calculation based on measured intake air molar flow rate, diluted exhaust gas molar flow rate, and dilute chemical balance\nExhaust gas molar flow rate ṅ exh [mol/s] may be calculated based on the measured intake air molar flow rate, ṅ int, the measured diluted exhaust gas molar flow rate, ṅ dexh, and the values calculated using the chemical balance in point 3.4.3. Note that the chemical balance must be based on diluted exhaust gas concentrations. For continuous-flow calculations, solve for the chemical balance in point 3.4.3 at the same frequency that ṅ int and ṅ dexh are updated and recorded. This calculated ṅ dexh may be used for the PM dilution ratio verification, the calculation of dilution air molar flow rate in the background correction in point 3.6.1 and the calculation of mass of emissions in point 3.5.1 for species that are measured in the raw exhaust gas.\nBased on diluted exhaust gas and intake air molar flow rate, exhaust gas molar flow rate, ṅ exh [mol/s] shall be calculated as follows:\nṅ exh = x raw/exhdry − x int/exhdry × 1 − x H2Oexh × ṅ dexh + ṅ int\n(7-114)\nwhere\nṅ exh raw exhaust gas molar flow rate from which emissions are measured [mol/s];\nx int/exhdry amount of intake air required to produce actual combustion products per mole of dry (raw or diluted) exhaust gas [mol/mol];\nx raw/exhdry amount of undiluted exhaust gas, without excess air, per mole of dry (raw or diluted) exhaust gas [mol/mol];\nx H2Oexh amount of water in exhaust gas per mole of exhaust gas [mol/mol];\nṅ dexh diluted exhaust gas molar flow rate from which emissions are measured [mol/s];\nṅ int intake air molar flow rate including humidity in intake air [mol/s].",
  "extent": "E+W+S+N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "F",
      "label": "F1",
      "text": "Substituted by Commission Delegated Regulation (EU) 2018/989 of 18 May 2018 amending and correcting Delegated Regulation (EU) 2017/654 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 (Text with EEA relevance)."
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/eur/2017/654/annex/VII/division/3/division/3.5/division/3.5.3",
    "retrieved_at": "2026-11-01T14:45:01.864924+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}