Document ID: chunk:federal_register_of_legislation:F2012C00283:reg:21:p13
Version: federal_register_of_legislation:F2012C00283
Segment Type: reg
Provision Reference: reg 21 (pt 13/39)
Character Range: 292339–295326

through the calibrated critical orifice. If the inlet pressure is high enough, the flow-rate (q), which is adjusted by means of the critical flow orifice, is independent of orifice outlet pressure (critical flow). If deviations exceeding 5 per cent occur, the cause of the malfunction shall be determined and corrected. The CVS system is operated as in an exhaust emission test for about 5 to 10 minutes. The gas collected in the sampling bag is analysed by the usual equipment and the results compared to the concentration of the gas samples which was known beforehand.
              3.3.  Gravimetric Method
              3.3.1.  Metering a limited quantity of pure gas (CO or C3H8) by means of a gravimetric technique.
              3.3.2.  The following gravimetric procedure may be used to verify the CVS system.
                The weight of a small cylinder filled with either carbon monoxide or propane is determined with a precision of ±0.01 g. For about 5 to 10 minutes, the CVS system is operated as in a normal exhaust emission test, while CO or propane is injected into the system. The quantity of pure gas involved is determined by means of differential weighing. The gas accumulated in the bag is then analysed by means of the equipment normally used for exhaust-gas analysis. The results are then compared to the concentration figures computed previously.

Annexe 4a -Appendix 3
  Gaseous emissions measurement equipment
              1.  Specification
              1.1.  System Overview
                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.
              1.2.  Sampling System Requirements
              1.2.1.  The sample of dilute exhaust gases shall be taken upstream from the suction device but downstream from the conditioning devices (if any).
              1.2.2.  The flow rate shall not deviate from the average by more than 2 per cent.
              1.2.3.  The sampling rate shall not fall below 5 litres per minute and shall not exceed 0.2 per cent of the flow rate of the dilute exhaust gases. An equivalent limit shall apply to constant-mass sampling systems.
              1.2.4.  A sample of the dilution air shall be taken at a constant flow rate near the ambient air-inlet (after the filter if one is fitted).
              1.2.5.  The dilution air sample shall not be contaminated by exhaust gases from the mixing area.
              1.2.6.  The sampling rate for the dilution air shall be comparable to that used in the case of the dilute exhaust gases.
              1.2.7.  The materials used for the sampling operations shall be such as not to change the pollutant concentration.
              1.2.8.  Filters