Document ID: chunk:federal_register_of_legislation:F2024C00356:reg:21:p16
Version: federal_register_of_legislation:F2024C00356
Segment Type: reg
Provision Reference: reg 21 (pt 16/35)
Character Range: 331606–334855

shall close automatically on the sampling-bag side; as an alternative, other ways of transporting the samples to the analyser may be used (three-way stopcocks, for instance);
              1.4.8.  Bags (B), for collecting samples of the diluted exhaust gas and of the dilution air during the test;
              1.4.9.  A sampling critical-flow venturi (SV), to take proportional samples of the diluted exhaust gas at sampling probe S2 A(CFV-CVS only);
              1.4.10.  A scrubber (PS), in the sampling line (CFV-CVS only);
              1.4.11.  Components for hydrocarbon sampling using HFID:
               Fh is a heated filter,
               S3 is a sampling point close to the mixing chamber,
               Vh is a heated multi-way valve,
               Q is a quick connector to allow the ambient air sample BA to be  analysed on the HFID,
               FID is a heated flame ionisation analyser,
               R and I are a means of integrating and recording the instantaneous  hydrocarbon concentrations,
               Lh is a heated sample line.
              2.  Calibration procedures
              2.1.  Analyser Calibration Procedure
              2.1.1.  Each analyser shall be calibrated as often as necessary and in any case in the month before type approval testing and at least once every six months for verifying conformity of production.
              2.1.2.  Each normally used operating range shall be calibrated by the following procedure:
              2.1.2.1. The analyser calibration curve is established by at least five calibration points spaced as uniformly as possible. The nominal concentration of the calibration gas of the highest concentration shall be not less than 80 per cent of the full scale.
              2.1.2.2. The calibration gas concentration required may be obtained by means of a gas divider, diluting with purified N2 or with purified synthetic air. The accuracy of the mixing device shall be such that the concentrations of the diluted calibration gases may be determined to within ±2 per cent.
              2.1.2.3. The calibration curve is calculated by the least squares method. If the resulting polynomial degree is greater than 3, the number of calibration points shall be at least equal to this polynomial degree plus 2.
              2.1.2.4. The calibration curve shall not differ by more than 2 per cent from the nominal value of each calibration gas.
              2.1.3.  Trace of the calibration curve
                From the trace of the calibration curve and the calibration points, it is possible to verify that the calibration has been carried out correctly. The different characteristic parameters of the analyser shall be indicated, particularly:
                The scale;
                The sensitivity;
                The zero point;
                The date of carrying out the calibration.
              2.1.4.  If it can be shown to the satisfaction of the technical service that alternative technology (e.g. computer, electronically controlled range switch, etc.) can give equivalent accuracy, then these alternatives may be used.
              2.2.  Analyser Verification Procedure
              2.2.1.  Each normally used operating range shall be checked