{
  "url": "https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-2/division-2.1/division-2.1.3",
  "json_url": "https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-2/division-2.1/division-2.1.3.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/2/division/2.1/division/2.1.3",
  "kind": "division",
  "number": "2.1.3",
  "heading": "Dry-to-wet concentration conversion",
  "text": "If the emissions are measured on a dry basis, the measured concentration c d on dry basis shall be converted to the concentration c w on a wet basis by means of equation (7-3):\nc w = k w × c d\n(7-3)\nwhere:\nk w dry-to-wet conversion factor [-]\nc d emission concentration on a dry basis [ppm] or [% vol]\nFor complete combustion, the dry-to-wet conversion factor for raw exhaust gas is written as k w,a [-] and shall be calculated by means of equation (7-4):\nk w,a = 1 − 1,2442 × H a + 111,19 × w H × q m f, i q m ad, i 773,4 + 1,2442 × H a + q m f, i q m ad, i × k f × 1000 1 − p r p b\n(7-4)\nwhere:\nH a intake air humidity [g H2O/kg dry air]\nqm f, i instantaneous fuel flow rate [kg/s]\nqm ad, i instantaneous dry intake air flow rate [kg/s]\np r water pressure after cooler [kPa]\np b total barometric pressure [kPa]\nw H hydrogen content of the fuel [% mass]\nk f combustion additional volume [m3/kg fuel]\nwith:\nk f = 0,055594 × w H + 0,0080021 × w N + 0,0070046 × w o\n(7-5)\nwhere:\nw H hydrogen content of fuel [% mass]\nw N nitrogen content of fuel [% mass]\nw O oxygen content of fuel [% mass]\nIn equation (7-4), the ratio p r/p b may be assumed:\n1 1 − p r p b = 1,008\n(7-6)\nFor incomplete combustion (rich fuel air mixtures) and also for emission tests without direct air flow measurements, a second method of k w,a calculation is preferred:\nk w,a = 1 1 + α × 0,005 × c CO2 + c CO − K w1 1 − p r p b\n(7-7)\nwhere:\nc CO2 concentration of CO2 in the raw exhaust gas, on a dry basis [per cent vol]\nc CO concentration of CO in the raw exhaust gas, on a dry basis [ppm]\np r water pressure after cooler [kPa]\np b total barometric pressure [kPa]\nα molar to carbon hydrogen ratio [-]\nk w1 intake air moisture [-]\nk w1 = 1,608 × H a 1000 + 1,608 × H a\n(7-8)",
  "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/2/division/2.1/division/2.1.3",
    "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."
}