# 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 2.6.2: Calculation procedure

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

The drift correction shall be calculated by means of equation (7-76):
c i driftcor = c refzero + c refspan − c refzero 2 c i − c prezero + c postzero c prespan + c postspan − c prezero + c postzero
(7-76)
Where:
ci driftcor concentration corrected for drift [ppm]
c refzero reference concentration of the zero gas, which is usually zero unless known to be otherwise [ppm]
c refspan reference concentration of the span gas [ppm]
c prespan pre-test interval gas analyzer response to the span gas concentration [ppm]
c postspan post-test interval gas analyzer response to the span gas concentration [ppm]
ci or c – concentration recorded, i.e. measured, during test, before drift correction [ppm]
c prezero pre-test interval gas analyzer response to the zero gas concentration [ppm]
c postzero post-test interval gas analyzer response to the zero gas concentration [ppm]

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Source: https://www.legislation.gov.uk/eur/2017/654/annex/VII/division/2/division/2.6/division/2.6.2 (the official version)
Page: https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-2/division-2.6/division-2.6.2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.