Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:9:p27
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 9 (pt 27/71)
Character Range: 284992–288146

0,1 ppm NO)

              Purified oxygen

                (Purity > 99,5 % vol O2)

              Hydrogen-helium mixture

                (40 ± 2 % hydrogen, balance helium) (Contamination ≤ 1 ppm C1, ≤ 400 ppm CO2)
              Purified synthetic air

                (Contamination ≤ 1 ppm C1, ≤ 1 ppm CO, ≤ 400 ppm CO2, ≤ 0,1 ppm NO) (Oxygen content between 18-21 % vol.)
              Purified propane or CO for the CVS verification

1.2.2.                        Calibration and span gases

              Mixtures of gases having the following chemical compositions shall be available: C3H8 and purified synthetic air (see Section 1.2.1);
              CO and purified nitrogen;

              NOx and purified nitrogen (the amount of NO2 contained in this calibration gas must not exceed 5 % of the NO content);

              CO2 and purified nitrogen; CH4 and purified synthetic air; C2H6 and purified synthetic air.
              Note: Other gas combinations are allowed provided the gases do not react with one another.

              The true concentration of a calibration and span gas must be within ± 2 % of the nominal value. All concentrations of calibration gas shall be given on a volume basis (volume percent or volume ppm).

              The gases used for calibration and span may also be obtained by means of a gas divider, diluting with purified N2 or with purified synthetic air. The accuracy of the mixing device must be such that the concentration of the diluted calibration gases may be determined to within ± 2 %.

1.3.                            Operating procedure for analysers and sampling system

              The operating procedure for analysers shall follow the start-up and operating instructions of the instrument manufacturer. The minimum requirements given in Sections 1.4 to 1.9 shall be included.

1.4.                            Leakage test

              A system leakage test shall be performed. The probe shall be disconnected from the exhaust system and the end plugged. The analyser pump shall be switched on. After an initial stabilisation period all flow meters should read zero. If not, the sampling lines shall be checked and the fault corrected.

              The maximum allowable leakage rate on the vacuum side shall be 0,5 % of the in-use flow rate for the portion of the system being checked. The analyser flows and bypass flows may be used to estimate the in- use flow rates.

              Another method is the introduction of a concentration step change at the beginning of the sampling line by switching from zero to span gas. If after an adequate period of time the reading shows a lower concentration compared to the introduced concentration, this points to calibration or leakage problems.

1.5.                            Calibration procedure

1.5.1.                        Instrument assembly

              The instrument assembly shall be calibrated and calibration curves checked against standard gases.  The same gas flow rates shall be used as when sampling exhaust.

1.5.2.                        Warming-up time

              The warming-up time should be according to