{
  "url": "https://openlegislation.uk/eu-regulation-2017-654/annex-VI/division-8/division-8.1/division-8.1.12",
  "json_url": "https://openlegislation.uk/eu-regulation-2017-654/annex-VI/division-8/division-8.1/division-8.1.12.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/VI/division/8/division/8.1/division/8.1.12",
  "kind": "division",
  "number": "8.1.12",
  "heading": "Sample dryer verification",
  "text": "If a humidity sensor for continuous monitoring of dew point at the sample dryer outlet is used this check does not apply, as long as it is ensured that the dryer outlet humidity is below the minimum values used for quench, interference, and compensation checks.\nIf a sample dryer is used as allowed in point 9.3.2.3.1 to remove water from the sample gas, the performance shall be verified upon installation, after major maintenance, for thermal chillers. For osmotic membrane dryers, the performance shall be verified upon installation, after major maintenance, and within 35 days of testing.\nWater can inhibit an analyzer's ability to properly measure the exhaust component of interest and thus is sometimes removed before the sample gas reaches the analyzer. For example water can negatively interfere with a CLD's NO x response through collisional quenching and can positively interfere with an NDIR analyzer by causing a response similar to CO.\nThe sample dryer shall meet the specifications as determined in point 9.3.2.3.1 for dew point, T dew , and absolute pressure, p total , downstream of the osmotic-membrane dryer or thermal chiller.\nThe following sample dryer verification procedure method shall be used to determine sample dryer performance, or good engineering judgment shall be used to develop a different protocol:\n(i) polytetrafluoroethylene ( ‘ PTFE ’ ) or stainless steel tubing shall be used to make necessary connections;\n(ii) N 2 or purified air shall be humidified by bubbling it through distilled water in a sealed vessel that humidifies the gas to the highest sample dew point that is estimated during emission sampling;\n(iii) The humidified gas shall be introduced upstream of the sample dryer;\n(iv) The humidified gas temperature downstream of the vessel shall be maintained at least 5 K (5 °C) above its dew point;\n(v) The humidified gas dew point, T dew , and pressure, p total , shall be measured as close as possible to the inlet of the sample dryer to verify that the dew point is the highest that was estimated during emission sampling;\n(vi) The humidified gas dew point, T dew , and pressure, p total , shall be measured as close as possible to the outlet of the sample dryer;\n(vii) The sample dryer meets the verification if the result of point (d)(vi) of this section is less than the dew point corresponding to the sample dryer specifications as determined in point 9.3.2.3.1 plus 2 K (2 °C) or if the mol fraction from (d)(vi) is less than the corresponding sample dryer specifications plus 0,002 mol/mol or 0,2 volume %. Note for this verification, sample dew point is expressed in absolute temperature, Kelvin.",
  "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/VI/division/8/division/8.1/division/8.1.12",
    "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."
}