Document ID: chunk:federal_register_of_legislation:F2024L00447:reg:0:p26
Version: federal_register_of_legislation:F2024L00447
Segment Type: reg
Provision Reference: reg 0 (pt 26/57)
Character Range: 163852–166663

and CLD or HCLD; the CO2 and NO values shall be recorded as B and C, respectively. The CO2 gas flow shall then be shut off and only the NO span gas shall be passed through the CLD or HCLD; the NO value shall be recorded as D. The per cent quench shall be calculated as:

                  where:

A  is the undiluted CO2 concentration measured with the NDIR [%]

B  is the diluted CO2 concentration measured with the NDIR [%]

C  is the diluted NO concentration measured with the CLD or HCLD [ppm]

D  is the undiluted NO concentration measured with the CLD or HCLD [ppm]

Alternative methods of diluting and quantifying of CO2 and NO span gas values such as dynamic mixing/blending are permitted upon approval of the approval authority.
                     (ii) Water quench check

                     This check applies to measurements of wet gas concentrations only. The calculation of water quench shall consider dilution of the NO span gas with water vapour and the scaling of the water vapour concentration in the gas mixture to concentration levels that are expected to occur during an emissions test. 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 CLD or HCLD; the NO value shall be recorded as D. The NO span gas shall then be bubbled through water at room temperature and passed through the CLD or HCLD; the NO value shall be recorded as Cb. 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 water temperature of the bubbler F shall be determined and recorded as G. The water vapour concentration H [%] of the gas mixture shall be calculated as:

                     The expected concentration of the diluted NO-water vapour span gas shall be recorded as De after being calculated as:

                     For diesel exhaust, the maximum concentration of water vapour in the exhaust gas (in per cent) expected during the test shall be recorded as Hm after being estimated, under the assumption of a fuel H/C ratio of 1.8/1, from the maximum CO2 concentration in the exhaust gas A as follows:

                     The per cent water quench shall be calculated as:

                     where:

De  is the expected diluted NO concentration [ppm]

Cb  is the measured diluted NO concentration [ppm]

Hm  is the maximum water vapour concentration [%]

H   is the actual water vapour concentration [%]

(iii) Maximum allowable quench
                     The combined CO2 and water quench shall not exceed 2 per cent of full scale.

                  (d) Quench check for NDUV analysers

                  Hydrocarbons and water can positively interfere with NDUV