Document ID: chunk:federal_register_of_legislation:F2008C00323:reg:120:p3
Version: federal_register_of_legislation:F2008C00323
Segment Type: reg
Provision Reference: reg 120 (pt 3/23)
Character Range: 244121–247294

 5 per cent of the theoretical value for each instantaneous value;

         3.1.2.   2 per cent of the theoretical value for the average value calculated for each sequence of the cycle.

         3.2.  The limit given in paragraph 3.1.1. above is brought to  50 per cent for one second when starting and, for vehicles with manual transmission, for two seconds during gear changes.

         4.  VERIFICATION PROCEDURE

         4.1.  Verification is carried out during each test throughout the cycle defined in paragraph 2.1. of Annex 4.

         4.2.  However, if the requirements of paragraph 3. above are met, with instantaneous accelerations which are at least three times greater or smaller than the values obtained in the sequences of the theoretical cycle, the verification described above will not be necessary.

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Annex 4 - Appendix 5

DEFINITION OF GAS-SAMPLING SYSTEMS

         1.   INTRODUCTION

         1.1.   There are several types of sampling devices capable of meeting the requirements set out in paragraph 4.2. of Annex 4.
         The devices described in paragraphs 3.1. and 3.2. below shall be deemed acceptable if they satisfy the main criteria relating to the variable dilution principle.

         1.2.  In its communications, the laboratory shall mention the system of sampling used when performing the test.

         2. CRITERIA RELATING TO THE VARIABLE-DILUTION SYSTEM
           FOR MEASURING EXHAUST-GAS EMISSIONS

         2.1.   Scope

         This section shall specify the operating characteristics of an exhaust-gas sampling system intended to be used for measuring the true mass emissions of a vehicle exhaust in accordance with the provisions of this Regulation.

         The principle of variable-dilution sampling for measuring mass emissions shall require three conditions to be satisfied:

         2.1.1.  The vehicle exhaust gases shall be continuously diluted with ambient air under specified conditions;

         2.1.2.  The total volume of the mixture of exhaust gases and dilution air shall be measured accurately;

         2.1.3.  A continuously proportional sample of the diluted exhaust gases and the dilution air shall be collected for analysis.

         Mass gaseous emissions shall be determined from the proportional sample concentrations and the total volume measured during the test. The sample concentrations shall be corrected to take account of the pollutant content of the ambient air.

         In addition, where vehicles are equipped with compression-ignition engines, their particulate emissions shall be plotted.

         2.2.  Technical summary

         Figure 5/1 gives a schematic diagram of the sampling system.

         2.2.1.1.  The vehicle exhaust gases shall be diluted with a sufficient amount of ambient air to prevent any water condensation in the sampling and measuring system.

         2.2.2.  The exhaust-gas sampling system shall be so designed as to make it possible to measure the average volume concentrations of the CO2, CO, HC and NOx, and, in addition, in the case of vehicles equipped with compression-ignition engines, of the particulate emissions, contained