{
  "url": "https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-1/division-1.1",
  "json_url": "https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-1/division-1.1.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/1/division/1.1",
  "kind": "division",
  "number": "1.1",
  "heading": "General symbols",
  "text": "See subscripts; e.g.: ṁ air for mass rate of dry air, ṁ fuel for fuel mass rate, etc.\nDilution ratio r d in section 2 and DR in section 3: different symbols but same meaning and same equations. Dilution factor D in section 2 and x dil in section 3: different symbols but same physical meaning; equation (7-124) shows the relationship between x dil and DR.\nt.b.d.= to be defined.\nSection 2\nSection 3\nUnit\nQuantity\nA\nm2\nArea\nAt\nm2\nVenturi throat cross-sectional area\nb, D 0\na 0\nt.b.d.\ny intercept of the regression line\nA/F st\n—\nStoichiometric air to fuel ratio\nC\n—\nCoefficient\nC d\nC d\n—\nDischarge coefficient\nC f\n—\nFlow coefficient\nc\nx\nppm, % vol\nConcentration/mole fraction (μmol/mol = ppm)\nc d\nppm, % vol\nConcentration on dry basis\nc w\nppm, % vol\nConcentration on wet basis\ncb\nppm, % vol\nBackground concentration\nD\nx dil\n—\nDilution factor\nD 0\nm3/rev\nPDP calibration intercept\nd\nd\nm\nDiameter\nd V\nm\nThroat diameter of venturi\ne\ne\ng/kWh\nBrake specific basis\ne gas\ne gas\ng/kWh\nSpecific emission of gaseous components\ne PM\ne PM\ng/kWh\nSpecific emission of particulates\nE\n1 – PF\n%\nConversion efficiency (PF = Penetration fraction)\nF s\n—\nStoichiometric factor\nf\nHz\nFrequency\nf c\n—\nCarbon factor\nγ\n—\nRatio of specific heats\nH\ng/kg\nAbsolute humidity\nK\n—\nCorrection factor\nK V\nK × m 4 × s ∕ kg\nCFV calibration function\nk f\nm3/kg fuel\nFuel specific factor\nk h\n—\nHumidity correction factor for NOx, diesel engines\nk Dr\nk Dr\n—\nDownward adjustment factor\nk r\nk r\n—\nMultiplicative regeneration factor\nk Ur\nk Ur\n—\nUpward adjustment factor\nk w,a\n—\nDry to wet correction factor for the intake air\nk w,d\n—\nDry to wet correction factor for the dilution air\nk w,e\n—\nDry to wet correction factor for the diluted exhaust gas\nk w,r\n—\nDry to wet correction factor for the raw exhaust gas\nμ\nμ\nkg/(m·s)\nDynamic viscosity\nM\nM\ng/mol\nMolar mass\nM a\ng/mol\nMolar mass of the intake air\nM e\nv\ng/mol\nMolar mass of the exhaust gas\nM gas\nM gas\ng/mol\nMolar mass of gaseous components\nm\nm\nkg\nMass\nm\na 1\nt.b.d.\nSlope of the regression line\nν\nm2/s\nKinematic viscosity\nm d\nv\nkg\nMass of the dilution air sample passed through the particulate sampling filters\nm ed\nkg\nTotal diluted exhaust gas mass over the cycle\nm edf\nkg\nMass of equivalent diluted exhaust gas over the test cycle\nm ew\nkg\nTotal exhaust gas mass over the cycle\nm f\nmg\nParticulate sample mass collected\nm f,d\nmg\nParticulate sample mass of the dilution air collected\nm gas\nm gas\ng\nMass of gaseous emissions over the test cycle\nm PM\nm PM\ng\nMass of particulate emissions over the test cycle\nm se\nkg\nExhaust gas sample mass over the test cycle\nm sed\nkg\nMass of diluted exhaust gas passing the dilution tunnel\nm sep\nkg\nMass of diluted exhaust gas passing the particulate collection filters\nm ssd\nkg\nMass of secondary dilution air\nN\n—\nTotal number of a series\nn\nmol\nAmount of substance\nṅ\nmol/s\nAmount of substance rate\nn\nf n\nmin– 1\nEngine rotational speed\nn p\nr/s\nPDP pump speed\nP\nP\nkW\nPower\np\np\nkPa\nPressure\np a\nkPa\nDry atmospheric pressure\np b\nkPa\nTotal atmospheric pressure\np d\nkPa\nSaturation vapour pressure of the dilution air\np p\np abs\nkPa\nAbsolute pressure\np r\np H2O\nkPa\nWater vapour pressure\np s\nkPa\nDry atmospheric pressure\n1 — E\nPF\n%\nPenetration fraction\nqm\nṁ\nkg/s\nMass rate\nqm ad\nṁ\nkg/s\nIntake air mass flow rate on dry basis\nqm aw\nkg/s\nIntake air mass flow rate on wet basis\nqm Ce\nkg/s\nCarbon mass flow rate in the raw exhaust gas\nqm Cf\nkg/s\nCarbon mass flow rate into the engine\nqm Cp\nkg/s\nCarbon mass flow rate in the partial flow dilution system\nqm dew\nkg/s\nDiluted exhaust gas mass flow rate on wet basis\nqm dw\nkg/s\nDilution air mass flow rate on wet basis\nqm edf\nkg/s\nEquivalent diluted exhaust gas mass flow rate on wet basis\nqm ew\nkg/s\nExhaust gas mass flow rate on wet basis\nqm ex\nkg/s\nSample mass flow rate extracted from dilution tunnel\nqm f\nkg/s\nFuel mass flow rate\nqm p\nkg/s\nSample flow of exhaust gas into partial flow dilution system\nqV\nV̇\nm3/s\nVolume flow rate\nqV CVS\nm3/s\nCVS volume rate\nqV s\ndm3/min\nSystem flow rate of exhaust gas analyzer system\nqV t\ncm3/min\nTracer gas flow rate\nρ\nρ\nkg/m3\nMass density\nρ e\nkg/m3\nExhaust gas density\nr\n—\nRatio of pressures\nr d\nDR\n—\nDilution ratio\nRa\nμm\nAverage surface roughness\nRH\n%\nRelative humidity\nr D\nβ\nm/m\nRatio of diameters (CVS systems)\nr p\n—\nPressure ratio of SSV\nRe\nRe#\n—\nReynolds number\nS\nK\nSutherland constant\nσ\nσ\n—\nStandard deviation\nT\nT\n°C\nTemperature\nT\nNm\nEngine torque\nT a\nK\nAbsolute temperature\nt\nt\ns\nTime\nΔt\nΔt\ns\nTime interval\nu\n—\nRatio between densities of gas component and exhaust gas\nV\nV\nm3\nVolume\nqV\nV̇\nm3/s\nVolume rate\nV 0\nm3/r\nPDP gas volume pumped per revolution\nW\nW\nkWh\nWork\nW act\nW act\nkWh\nActual cycle work of the test cycle\nWF\nWF\n—\nWeighting factor\nw\nw\ng/g\nMass fraction\nx –\nmol/mol\nFlow-weighted mean concentration\nX 0\nK s\ns/rev\nPDP calibration function\ny\n—\nGeneric variable\ny –\ny –\nArithmetic mean\nZ\n—\nCompressibility factor",
  "extent": "E+W+S+N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "footnote",
      "label": "f1",
      "text": "t.b.d.= to be defined."
    },
    {
      "type": "footnote",
      "label": "f2",
      "text": "See subscripts; e.g.: ṁ air for mass rate of dry air, ṁ fuel for fuel mass rate, etc."
    },
    {
      "type": "footnote",
      "label": "f3",
      "text": "Dilution ratio r d in section 2 and DR in section 3: different symbols but same meaning and same equations. Dilution factor D in section 2 and x dil in section 3: different symbols but same physical meaning; equation (7-124) shows the relationship between x dil and DR."
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/eur/2017/654/annex/VII/division/1/division/1.1",
    "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."
}