Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:10:p15
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 10 (pt 15/30)
Character Range: 561631–564399

using a lower flow rate and/or a larger diameter filter.

        3.8.3.2. Partial flow dilution system

              At the start of the engine or test sequence, if the cycle is started directly from the preconditioning, the particulate sampling system shall be switched from by-pass to collecting particulates.

              For the control of a partial flow dilution system, a fast system response is required. The transformation time for the system shall be determined by the procedure in section 3.3 of Appendix 5 to Annex III. If the combined transformation time of the exhaust flow measurement (see section 4.2.1) and the partial flow system is less than 0,3 sec, online control may be used. If the transfor- mation time exceeds 0,3 sec, look ahead control based on a pre-recorded test run must be used. In this case, the rise time shall be ≤ 1 sec and the delay time of the combination ≤ 10 sec.

              The total system response shall be designed as to ensure a representative sample of the particulates, qmp,i, proportional to the exhaust mass flow. To determine the proportionality, a regression analysis of qmp,i versus qmew,i shall be conducted on a mini- mum 1 Hz data acquisition rate, and the following criteria shall be met:

              - The correlation coefficient R2 of the linear regression between qmp,i and qmew,i shall not be less than 0,95,

              - The standard error of estimate of qmp,i on qmew,i shall not exceed 5 % of qmp maximum,

              - qmp intercept of the regression line shall not exceed ± 2 % of qmp maximum.

              Optionally, a pretest may be run, and the exhaust mass flow signal of the pretest be used for controlling the sample flow into the particulate system (look-ahead control). Such a procedure is required if the transformation time of the particulate system, t50,P or the transformation time of the exhaust mass flow signal, t50,F, or both, are > 0,3 sec. A correct control of the partial dilution sys- tem is obtained, if the time trace of qmew,pre of the pretest, which controls qmp, is shifted by a look-ahead time of t50,P + t50,F.

              For establishing the correlation between qmp,i and qmew,i the data taken during the actual test shall be used, with qmew,i time aligned by t50,F relative to qmp,i (no contribution from t50,P to the time alignment). That is, the time shift between qmew and qmp is the difference in their transformation times that were determined in section 3.3 of Appendix 5 to Annex III.

        3.8.4. Engine stalling

              If the engine stalls anywhere during the test cycle, the engine shall be preconditioned and restarted, and the test repeated. If a mal- function occurs in any of the required test equipment during the test cycle,