6.3 Test procedures for SCR chambers

  6.3.1.1 The SCR chamber for validation testing may be either a full scale SCR chamber or a scaled version. A SCR chamber should demonstrate the reduction in NO_x concentrations (ppm) expected in exhaust gas measured in section 6.2 of these guidelines. Therefore, NO_x reduction rate of the SCR chamber should be determined for each individual mode point. Where undertaken on a scaled version of the SCR chamber the scaling process should be validated to the satisfaction of the Administration.

  6.3.2.1 Exhaust gas, catalyst, reductant and an injection system should satisfy the following conditions at each mode point:

• .1 Exhaust gas flow
  Exhaust gas flow rate for the test should be scaled accordingly to account for the dimension of the catalyst model.

• .2 Exhaust gas component
  Exhaust gas for the test should either be diesel engine exhaust gas or simulated gas.

  Where diesel exhaust gas is used it should correspond, in terms of concentrations, to the exhaust gas in section 6.2 of these guidelines, in terms of NO_x, O₂, CO₂, H₂O, and SO₂ (±5% of the required concentration for each emission species).

  Where simulated gas is used it should correspond, in terms of concentrations, to the exhaust gas in section 6.2 of these guidelines, in terms of NO, NO₂, O₂, CO₂, H₂O, and SO₂ (±5% of the required concentration for each emission species) balance N₂.

• .3 Exhaust gas temperature
  The temperature of exhaust gas used for the test should correspond to the temperatures obtained from testing in section 6.2 of these guidelines, ensuring that the SCR chamber is activated at every load point, other than as provided for by 3.1.4 of the NTC 2008, and that no ammonia bisulphate formation, or reductant destruction, takes place.

• .4 Catalyst blocks and AV,SV value
  The catalyst blocks used in the test should be representative of the catalyst blocks to be used in the SCR chamber in service. AV,SV or LV value should, in the case of full scale tests, be within a range of ±20% of the required value as obtained in testing from section 6.2 of these guidelines. In the case of scaled tests it should correspond to the above.

• .5 Reductant
  The reductant concentration should be representative of the reductant concentration in the exhaust gas during actual operation.

  6.3.3.1 All measurements should be recorded after they have stabilized.

  6.3.4.1 Operating data which is to be given in the Technical File should be derived from the modelling process or otherwise justified.

  6.3.4.2 Exhaust gas analysers should be in accordance with appendix III and appendix IV of the NTC 2008 or otherwise to the satisfaction of the Administration.

  6.3.5.1 Data recorded under paragraph 6.3.1.1 of these guidelines should be recorded in the test report as required by section 5.10 of the NTC 2008.