# 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 8.2.1.2: Partial flow dilution system validation

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

For the control of a partial flow dilution system to extract a proportional raw exhaust gas sample, a fast system response is required; this is identified by the promptness of the partial flow dilution system. The transformation time for the system shall be determined in accordance with the procedure set out in point 8.1.8.6.3.2. The actual control of the partial flow dilution system shall be based on the current measured conditions. If the combined transformation time of the exhaust gas flow measurement and the partial flow system is ≤ 0,3 s, online control shall be used. If the transformation time exceeds 0,3 s, look-ahead control based on a pre-recorded test run shall be used. In this case, the combined rise time shall be ≤ 1 s and the combined delay time ≤ 10 s. The total system response shall be designed as to ensure a representative sample of the particulates, qm p,i (sample flow of exhaust gas into partial flow dilution system), proportional to the exhaust gas mass flow. To determine the proportionality, a regression analysis of qm p,i versus qm ew,i (exhaust gas mass flow rate on wet basis) shall be conducted on a minimum 5 Hz data acquisition rate, and the following criteria shall be met:
(a) The correlation coefficient r 2 of the linear regression between qm p,i and qm ew,i shall not be less than 0,95;
(b) The standard error of estimate of qm p,i on qm ew,i shall not exceed 5 % of qm p maximum;
(c) qm p intercept of the regression line shall not exceed ± 2 % of qm p maximum.
Look-ahead control is required if the combined transformation times of the particulate system, t 50,P and of the exhaust gas mass flow signal, t 50,F are > 0,3 s. In this case, a pre-test shall be run and the exhaust gas mass flow signal of the pre-test be used for controlling the sample flow into the particulate system. A correct control of the partial dilution system is obtained, if the time trace of qm ew,pre of the pre-test, which controls qm p, is shifted by a ‘look-ahead’ time of t 50,P + t 50,F.
For establishing the correlation between qm p,i and qm ew,i the data taken during the actual test shall be used, with qm ew,i time aligned by t 50,F relative to qm p,i (no contribution from t 50,P to the time alignment). The time shift between qm ew and qm p is the difference between their transformation times that were determined in point 8.1.8.6.3.2.

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Source: https://www.legislation.gov.uk/eur/2017/654/annex/VI/division/8/division/8.2/division/8.2.1/division/8.2.1.2 (the official version)
Page: https://openlegislation.uk/eu-regulation-2017-654/annex-VI/division-8/division-8.2/division-8.2.1/division-8.2.1.2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.