Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:110:p2
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 110 (pt 2/59)
Character Range: 607960–610838

of accepting the sample filter weights or voiding the tests, fixing the weighing room control system and re-running the test.

        4.2.3. Analytical balance

              The analytical balance used to determine the filter weight shall have a precision (standard deviation) of at least 2 μg and a reso- lution of at least 1 μg (1 digit = 1 μg) specified by the balance manufacturer.

        4.2.4. Elimination of static electricity effects

              To eliminate the effects of static electricity, the filters shall be neutralized prior to weighing, e.g. by a Polonium neutralizer, a Fara- day cage or a device of similar effect.

        4.2.5. Specifications for flow measurement

        4.2.5.1. General requirements

              Absolute accuracies of flow meter or flow measurement instrumentation shall be as specified in section 2.2.

        4.2.5.2. Special provisions for partial flow dilution systems

              For partial flow dilution systems, the accuracy of the sample flow qmp is of special concern, if not measured directly, but deter- mined by differential flow measurement:

              qmp = qmdew – qmdw

              In this case an accuracy of ± 2 % for qmdew and qmdw is not sufficient to guarantee acceptable accuracies of qmp. If the gas flow is determined by differential flow measurement, the maximum error of the difference shall be such that the accuracy of qmp is within ± 5 % 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 qmp can be obtained by either of the following methods:

              The absolute accuracies of qmdew and qmdw are ± 0,2 % which guarantees an accuracy of qmp of ≤ 5 % at a dilution ratio of 15. However, greater errors will occur at higher dilution ratios;

              calibration of qmdw relative to qmdew is carried out such that the same accuracies for qmp as in a) are obtained. For the details of such a calibration see section 3.2.1 of Appendix 5 to Annex III;

              the accuracy of qmp is determined indirectly from the accuracy of the dilution ratio as determined by a tracer gas, e.g. CO2. Again, accuracies equivalent to method a) for qmp are required;

              the absolute accuracy of qmdew and qmdw is within ± 2 % of full scale, the maximum error of the difference between qmdew and qmdw is within 0,2 %, and the linearity error is within ± 0,2 % of the highest qmdew observed during the test.

              (*) The Commission shall review the temperature upstream of the filter holder, 325 K (52 °C), and, if necessary propose an alternative tem- perature to be applicable for type-approval of new types from 1 October 2008.'

  (h)     Appendix 5 is amended as follows:

         (i)       The following section 1.2.3 is added:

        '1.2.3. Use