Division 5.5.1 Using the test set up as shown in Figure A5/15 and the procedure described below, the efficiency of converters for the conversion of NO2 into NO shall be tested by means of an ozonator as follows:

5.5.1.1.
The analyser shall be calibrated in the most common operating range following the manufacturer's specifications using zero and calibration gas (the NO content of which shall amount to approximately 80 per cent of the operating range and the NO₂ concentration of the gas mixture shall be less than 5 per cent of the NO concentration). The NO_x analyser shall be in the NO mode so that the calibration gas does not pass through the converter. The indicated concentration shall be included in all relevant test sheets.
5.5.1.2.
Via a T-fitting, oxygen or synthetic air shall be added continuously to the calibration gas flow until the concentration indicated is approximately 10 per cent less than the indicated calibration concentration given in paragraph 5.5.1.1. of this Sub-Annex. The indicated concentration (c) shall be included in all relevant test sheets. The ozonator shall be kept deactivated throughout this process.
5.5.1.3.
The ozonator shall now be activated to generate enough ozone to bring the NO concentration down to 20 per cent (minimum 10 per cent) of the calibration concentration given in paragraph 5.5.1.1. of this Sub-Annex. The indicated concentration (d) shall be included all relevant test sheets.
5.5.1.4.
The NO_x analyser shall be subsequently switched to the NO_x mode, whereby the gas mixture (consisting of NO, NO₂, O₂ and N₂) now passes through the converter. The indicated concentration (a) shall be included in all relevant test sheets.
5.5.1.5.
The ozonator shall now be deactivated. The mixture of gases described in paragraph 5.5.1.2. of this Sub-Annex shall pass through the converter into the detector. The indicated concentration (b) shall be included in all relevant test sheets.
Figure A5/15
NO_x converter efficiency test configuration
5.5.1.6.
With the ozonator deactivated, the flow of oxygen or synthetic air shall be shut off. The NO₂ reading of the analyser shall then be no more than 5 per cent above the figure given in paragraph 5.5.1.1. of this Sub-Annex.
5.5.1.7.
The per cent efficiency of the NO_x converter shall be calculated using the concentrations a, b, c and d determined in paragraphs 5.5.1.2. to 5.5.1.5. of this Sub-Annex inclusive using the following equation:
$Efficiency = (1 + \frac{a - b}{c - d}) \times 100$
F1The efficiency of the converter shall not be less than 95 per cent. The efficiency of the converter shall be tested in the frequency defined in Table A5/3.
F2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Annotations

Textual amendments

F1: Inserted by Commission Regulation (EU) 2018/1832 of 5 November 2018 amending Directive 2007/46/EC of the European Parliament and of the Council, Commission Regulation (EC) No 692/2008 and Commission Regulation (EU) 2017/1151 for the purpose of improving the emission type approval tests and procedures for light passenger and commercial vehicles, including those for in-service conformity and real-driving emissions and introducing devices for monitoring the consumption of fuel and electric energy (Text with EEA relevance).
F2: Deleted by Commission Regulation (EU) 2018/1832 of 5 November 2018 amending Directive 2007/46/EC of the European Parliament and of the Council, Commission Regulation (EC) No 692/2008 and Commission Regulation (EU) 2017/1151 for the purpose of improving the emission type approval tests and procedures for light passenger and commercial vehicles, including those for in-service conformity and real-driving emissions and introducing devices for monitoring the consumption of fuel and electric energy (Text with EEA relevance).