Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p39
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 39/56)
Character Range: 402791–405614

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 concentration (in per cent) of the mixture shall be calculated as follows:
                      H = 100 x (G / pb) (78)

 and recorded as H. The expected diluted NO span gas (in water vapour) concentration shall be calculated as follows:
                      De = D x ( 1- H / 100 ) (79)

 and recorded as De. The maximum exhaust water vapour concentration (in per cent) expected during testing shall be estimated from the maximum CO2 concentration in the exhaust gas A as follows:
                      Hm = α/2 x A  (80)

 and recorded as Hm
 The per cent water quench shall be calculated as follows:
                      EH2O = 100 x ( ( De - C ) / De) x (Hm / H) (81)

 Where:
 De is the expected diluted NO concentration, ppm
 C is the measured diluted NO concentration, ppm
 Hm is the maximum water vapour concentration, per cent
 H is the actual water vapour concentration, per cent
9.3.9.2.3. Maximum allowable quench
 The combined CO2 and water quench shall not exceed 2 per cent of full scale.
9.3.9.3. NOx analyzer quench check for NDUV analyzer
 Hydrocarbons and H2O can positively interfere with a NDUV analyzer by causing a response similar to NOx. If the NDUV analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, simultaneously such measurements shall be conducted to test the algorithms during the analyzer interference verification.
9.3.9.3.1. Procedure
 The NDUV analyzer shall be started, operated, zeroed, and spanned according to the instrument manufacturer's instructions. It is recommended to extract engine exhaust to perform this verification. A CLD shall be used to quantify NOx in the exhaust. The CLD response shall be used as the reference value. Also HC shall be measured in the exhaust with a FID analyzer. The FID response shall be used as the reference hydrocarbon value.
 Upstream of any sample dryer, if used during testing, the engine exhaust shall be introduced into the NDUV analyzer. Time shall be allowed for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response. While all analyzers measure the sample's concentration, 30 seconds of sampled data shall be recorded, and the arithmetic means for the three analyzers calculated.
 The CLD mean value shall be subtracted from the NDUV mean value. This difference shall be multiplied by the ratio of the expected mean HC concentration to the HC concentration measured during the verification, as follows:
                       (82)
 Where: