Document ID: chunk:federal_register_of_legislation:F2024L00447:reg:0:p29
Version: federal_register_of_legislation:F2024L00447
Segment Type: reg
Provision Reference: reg 0 (pt 29/57)
Character Range: 171678–174717

the NO2 calibration gas shall not exceed 5 per cent of the NO2 content.

              5.1.3. Multicomponent mixtures

              Only multicomponent mixtures which fulfil the requirements of paragraph 5.1.1. shall be used. These mixtures may contain two or more of the components. Multicomponent mixtures containing both NO and NO2 are exempted of the NO2 impurity requirement set out in paragraphs 5.1.1. and 5.1.2.

              5.2. Gas dividers

              Gas dividers (i.e., precision blending devices that dilute with purified N2 or synthetic air) can be used to obtain calibration and span gases. The accuracy of the gas divider shall be such that the concentration of the blended calibration gases is accurate to within ± 2 per cent. The verification shall be performed at between 15 and 50 per cent of full scale for each calibration incorporating a gas divider. An additional verification may be performed using another calibration gas, if the first verification has failed.

              Optionally, the gas divider may be checked with an instrument which by nature is linear, e.g. using NO gas in combination with a CLD. The span value of the instrument shall be adjusted with the span gas directly connected to the instrument. The gas divider shall be checked at the settings typically used and the nominal value shall be compared with the concentration measured by the instrument. The difference shall in each point be within ±1 per cent of the nominal concentration value.

              5.3. Oxygen interference check gases

              Oxygen interference check gases consist of a blend of propane, oxygen and nitrogen and shall contain propane at a concentration of 350 ± 75 ppmC1. The concentration shall be determined by gravimetric methods, dynamic blending or the chromatographic analysis of total hydrocarbons plus impurities. The oxygen concentrations of the oxygen interference check gases shall meet the requirements listed in Table A5/3; the remainder of the oxygen interference check gas shall consist of purified nitrogen.

    Table A5/3
    Oxygen interference check gases

                      Engine type

Compression ignition  Positive ignition
O2 concentration      21 ± 1 %           10 ± 1 %

10 ± 1 %              5 ± 1 %

5 ± 1 %               0.5 ± 0.5 %

6. Analysers for measuring (solid) particle emissions
              This section will define future requirement for analysers for measuring particle number emissions, once their measurement becomes mandatory.

              6.1. General

              The PN analyser shall consist of a pre-conditioning unit and a particle detector that counts with 50 per cent efficiency from approximately 23 nm. It is permissible that the particle detector also pre-conditions the aerosol. The sensitivity of the analysers to shocks, vibration, aging, variability in temperature and air pressure as well as electromagnetic interferences and other impacts related to vehicle and analyser operation shall be limited as far as possible and shall