Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p38
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 38/56)
Character Range: 400309–403035

lower than the maximum levels expected during testing may be run, but the observed H2O interference shall be scaled up by multiplying the observed interference by the ratio of the maximum expected H2O concentration value to the actual value used during this procedure. The sum of the two scaled interference values shall meet the tolerance specified in this paragraph.
9.3.9.2. NOx analyzer quench checks for CLD analyzer
 The two gases of concern for CLD (and HCLD) analyzers are CO2 and water vapour. Quench responses to these gases are proportional to their concentrations, and therefore require test techniques to determine the quench at the highest expected concentrations experienced during testing. If the CLD analyzer uses quench compensation algorithms that utilize H2O and/or CO2 measurement instruments, quench shall be evaluated with these instruments active and with the compensation algorithms applied.
9.3.9.2.1. CO2 quench check
 A CO2 span gas having a concentration of 80 to 100 per cent of full scale of the maximum operating range shall be passed through the NDIR analyzer and the CO2 value recorded as A. It shall then be diluted approximately 50 per cent with NO span gas and passed through the NDIR and CLD, with the CO2 and NO values recorded as B and C, respectively. The CO2 shall then be shut off and only the NO span gas be passed through the (H)CLD and the NO value recorded as D.
 The per cent quench shall be calculated as follows:
                       (77)

 Where:
A is the undiluted CO2 concentration measured with NDIR, per cent
B is the diluted CO2 concentration measured with NDIR, per cent
C is the diluted NO concentration measured with (H)CLD, ppm
D is the undiluted NO concentration measured with (H)CLD, ppm
 Alternative methods of diluting and quantifying of CO2 and NO span gas values such as dynamic mixing/blending are permitted with the approval of the Type Approval Authority.
9.3.9.2.2. Water quench check
 This check applies to wet gas concentration measurements only. Calculation of water quench shall 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 per cent to 100 per cent 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 water temperature shall be determined and recorded as F. The mixture's saturation vapour pressure that corresponds to the bubbler water temperature (F) shall be determined and recorded as G.
 The water vapour