Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:9:p32
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 9 (pt 32/71)
Character Range: 299035–301949

with CH4 bypassing the NMC
1.8.4.2.                    Ethane efficiency

              Ethane calibration gas shall be flown through the FID with and without bypassing the NMC and the two concentrations recorded. The efficiency shall be determined as follows
              where,

              concw = HC concentration with C2H6 flowing through the NMC concw/o   = HC concentration with C2H6 bypassing the NMC
1.9.                            1.9. Interference effects with CO, CO2, and NOx analysers

              Gases present in the exhaust other than the one being analysed can interfere with the reading in several ways. Positive interference occurs in NDIR instruments where the interfering gas gives the same effect as the gas being measured, but to a lesser degree. Negative interference occurs in NDIR instruments by the interfering gas broadening the absorption band of the measured gas, and in CLD instruments by the interfering gas quenching the radiation. The interference checks in Sections 1.9.1 and 1.9.2 shall be performed prior to an analyser's initial use and after major service intervals.

1.9.1.                        CO analyser interference check

              Water and CO2 can interfere with the CO analyser performance. Therefore, a CO2 span gas having a concentration of 80 to 100 % of full scale of the maximum operating range used during testing shall be bubbled through water at room temperature and the analyser response recorded. The analyser response must not be more than 1 % of full scale for ranges equal to or above 300 ppm or more than 3 ppm for ranges below 300 ppm.

1.9.2.                        NOx analyser quench checks

              The two gases of concern for CLD (and HCLD) analysers 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.

1.9.2.1.                    C O 2 quench check

              A CO2 span gas having a concentration of 80 to 100 % of full scale of the maximum operating range shall be passed through the NDIR analyser and the CO2 value recorded as A. It shall then be diluted approximately 50 % with NO span gas and passed through the NDIR and (H)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 quench, which must not be greater than 3 % of full scale, shall be calculated as follows:

              where,

              A    = is the undiluted CO2 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