# 1065.675 CLD quench verification calculations.
Perform CLD quench-check calculations as follows:
(a) Perform a CLD analyzer quench verification test as described in § 1065.370.
(b) Estimate the maximum expected mole fraction of water during emission testing, *x*<sub>H2Oexp.</sub> Make this estimate where the humidified NO span gas was introduced in § 1065.370(e)(6). When estimating the maximum expected mole fraction of water, consider the maximum expected water content in intake air, fuel combustion products, and dilution air (if applicable). If you introduced the humidified NO span gas into the sample system upstream of a sample dryer during the verification test, you need not estimate the maximum expected mole fraction of water and you must set *x*<sub>H2Oexp</sub> equal to *x*<sub>H2Omeas.</sub>
(c) Estimate the maximum expected CO<sub>2</sub> concentration during emission testing, *x*<sub>CO2exp</sub>. Make this estimate at the sample system location where the blended NO and CO<sub>2</sub> span gases are introduced according to § 1065.370(d)(10). When estimating the maximum expected CO<sub>2</sub> concentration, consider the maximum expected CO<sub>2</sub> content in fuel combustion products and dilution air.
(d) Calculate quench as follows:
Where:
*quench* = amount of CLD quench.
χ<sub>NOdry</sub> = concentration of NO upstream of a humidity generator, according to § 1065.370(e)(4).
χ<sub>NOwet</sub> = measured concentration of NO downstream of a humidity generator, according to § 1065.370(e)(9).
χ<sub>H2Oexp</sub> = maximum expected mole fraction of water during emission testing, according to paragraph (b) of this section.
χ<sub>H2Omeas</sub> = measured mole fraction of water during the quench verification, according to § 1065.370(e)(7).
χ<sub>NOmeas</sub> = measured concentration of NO when NO span gas is blended with CO<sub>2</sub> span gas, according to § 1065.370(d)(10).
χ<sub>NOact</sub> = actual concentration of NO when NO span gas is blended with CO<sub>2</sub> span gas, according to § 1065.370(d)(11) and calculated according to Eq. 1065.675-2.
χ<sub>CO2exp</sub> = maximum expected concentration of CO<sub>2</sub> during emission testing, according to paragraph (c) of this section.
χ<sub>CO2act</sub> = actual concentration of CO<sub>2</sub> when NO span gas is blended with CO<sub>2</sub> span gas, according to § 1065.370(d)(9).
Where:
χ<sub>NOspan</sub> = the NO span gas concentration input to the gas divider, according to § 1065.370(d)(5).
χ<sub>CO2span</sub> = the CO<sub>2</sub> span gas concentration input to the gas divider, according to § 1065.370(d)(4).
χ<sub>NOdry</sub> = 1800.0 µmol/mol
χ<sub>NOwet</sub> = 1739.6 µmol/mol
χ<sub>H2Oexp</sub> = 0.030 mol/mol
χ<sub>H2Omeas</sub> = 0.030 mol/mol
χ<sub>NOmeas</sub> = 1515.2 µmol/mol
χ<sub>NOspan</sub> = 3001.6 µmol/mol
χ<sub>CO2exp</sub> = 3.2%
χ<sub>CO2span</sub> = 6.1%
χ<sub>CO2act</sub> = 2.98%
*quench* = (−0.0036655−0.014020171) · 100% = −1.7685671%
[73 FR 59340, Oct. 8, 2008, as amended at 76 FR 57466, Sept. 15, 2011; 81 FR 74188, Oct. 25, 2016; 86 FR 34568, June 29, 2021; 88 FR 4686, Jan. 24, 2023]