Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:9:p33
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 9 (pt 33/71)
Character Range: 301692–304657

concentration measured with NDIR in %   B = is the diluted CO2 concentration measured with NDIR in %
              C    = is the diluted NO concentration measured with (H)CLD in ppm

              D   = is the undiluted NO concentration measured with (H)CLD in ppm

              Alternative methods of diluting and quantifying of CO2 and NO span gas values such as dynamic mixing/ blending can be used.

1.9.2.2.                    Water quench check

              This check applies to wet gas concentration measurements only. Calculation of water quench must consider dilution of the NO span gas with water vapour and scaling of water vapour concentration of the mixture to that expected during testing.

              A NO span gas having a concentration of 80 to 100 % of full scale of the normal operating range shall be passed through the (H)CLD and the NO value recorded as D. The NO span gas shall then be bubbled through water at room temperature and passed through the (H)CLD and the NO value recorded as C. The analyser's absolute operating pressure and the water temperature shall be determined and recorded as E and F, respectively. The mixture's saturation vapour pressure that corresponds to the bubbler water temperature F shall be determined and recorded as G. The water vapour concentration (H, in %) of the mixture shall be calculated as follows:

        H = 100 × (G/E)

              The expected diluted NO span gas (in water vapour) concentration (De) shall be calculated as follows:

        De = D × (1 – H/100)

              For diesel exhaust, the maximum exhaust water vapour concentration (Hm, in %) expected during testing shall be estimated, under the assumption of a fuel atom H/C ratio of 1,8:1, from the undiluted CO2 span gas concentration (A, as measured in Section 1.9.2.1) as follows:

        Hm = 0; 9 × A

              The water quench, which must not be greater than 3 %, shall be calculated as follows:

              where,

              De  = is the expected diluted NO concentration in ppm C    = is the diluted NO concentration in ppm
              Hm  = is the maximum water vapour concentration in % H   = is the actual water vapour concentration in %
                  Note: It is important that the NO span gas contains minimal NO2 concentration for this check, since absorption of NO2 in water has not been accounted for in the quench calculations.

1.10.                          Calibration intervals

              The analysers shall be calibrated according to Section 1.5 at least every three months or whenever a system repair or change is made that could influence calibration.

2.                                 CALIBRATION OF THE CVS-SYSTEM

2.1.                            General

              The CVS system shall be calibrated by using an accurate flowmeter traceable to national or international standards and a restricting device. The flow through the system shall be measured at different