Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p45
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 45/56)
Character Range: 418482–421184

rd or rs be determined such that the accuracy requirements of paragraph 9.4.6.2. are fulfilled.
9.4.6.1. System response time
 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 paragraph 9.4.6.6. If the combined transformation time of the exhaust flow measurement (see paragraph 8.4.1.2.) and the partial flow system is  ≤  0.3 second, online control shall be used. If the transformation time exceeds 0.3 second, look ahead control based on a pre-recorded test run shall be used. In this case, the combined rise time shall be    1 second and the combined delay time    10 seconds.
 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 minimum 5 Hz data acquisition rate, and the following criteria shall be met:
(a) The coefficient of determination r2 of the linear regression between qmp,i and qmew,i shall not be less than 0.95;
(b) The standard error of estimate of qmp,i on qmew,i shall not exceed 5 per cent of qmp maximum;
(c) qmp intercept of the regression line shall not exceed  2 per cent of qmp maximum.
 Look-ahead control is required if the combined transformation times of the particulate system, t50,P and of the exhaust mass flow signal, t50,F are  >  0.3 second. In this case, a pre-test shall be run, and the exhaust 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 qmew,pre of the pre-test, 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 paragraph 9.4.6.6.
9.4.6.2. Specifications for differential flow measurement
 For partial flow dilution systems, the accuracy of the sample flow qmp is of special concern, if not measured directly, but determined by differential flow measurement:

 qmp = qmdew – qmdw (83)
 In this case, the maximum error of the difference shall be such that the accuracy of qmp is within 5 per cent when the dilution ratio is less than 15. It can be calculated by taking root-mean-square of the errors of each instrument.

 Acceptable accuracies of