Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p2
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 2/27)
Character Range: 553819–557248

possible.
              A.7.2.2.3.              Cross interference
              The spectral resolution of the NH3 wavelength shall be within 0.5 cm-1 in order to minimize cross interference from other gases present in the exhaust gas.
              A.7.3.              Emissions test procedure and evaluation
              A.7.3.1.              Checking the analysers
              Prior to the emissions test, the analyser range shall be selected. Emission analysers with automatic or manual range switching shall be permitted. During the test cycle, the range of the analysers shall not be switched.
              Zero and span response shall be determined, if the provisions of paragraph A.7.3.4.2. do not apply for the instrument. For the span response, a NH3 gas that meets the specifications of paragraph A.7.4.2.7. shall be used. The use of reference cells that contain NH3 span gas is permitted.
              A.7.3.2.              Collection of emission relevant data
              At the start of the test sequence, the NH3 data collection shall be started, simultaneously. The NH3 concentration shall be measured continuously and stored with at least 1 Hz on a computer system.
              A.7.3.3.              Operations after test
              At the completion of the test, sampling shall continue until system response times have elapsed. Determination of analyser's drift according to paragraph A.7.3.4.1. shall only be required if the information in paragraph A.7.3.4.2. is not available.
              A.7.3.4.              Analyser drift
              A.7.3.4.1.              As soon as practical but no later than 30 minutes after the test cycle is complete or during the soak period, the zero and span responses of the analyser shall be determined. The difference between the pre-test and post-test results shall be less than 2 per cent of full scale.
              A.7.3.4.2.              Determination of analyser drift is not required in the following situations:
(a) If the zero and span drift specified by the instrument manufacturer in paragraphs A.7.4.2.3. and A.7.4.2.4. meets the requirements of paragraph A.7.3.4.1.,
(b) The time interval for zero and span drift specified by the instrument manufacturer in paragraphs A.7.4.2.3. and A.7.4.2.4. exceeds the duration of the test.
              A.7.3.5.              Data evaluation
              The average NH3 concentration (ppm/test) shall be determined by integrating the instantaneous values over the cycle. The following equation shall be applied:

               (115)
              Where:
              cNH3,I  is the instantaneous NH3 concentration in the exhaust gas, ppm
              n   is the number of measurements
              For the WHTC, the final test result shall be determined with the following equation:
                (116)
              Where:
              cNH3,cold is the average NH3 concentration of the cold start test, ppm
              cNH3,hot  is the average NH3 concentration of the hot start test, ppm
              A.7.4.              Analyser specification and verification
              A.7.4.1.              Linearity requirements
              The analyser shall comply with the linearity requirements specified in Table 7 of this annex. The linearity verification in accordance with paragraph 9.2.1. of this annex, shall be performed at least every 12 months or whenever a system repair or change is