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Division 5.2.2 Each normally used operating range shall be linearized by the following procedure:

Original text. Later amendments are not shown.

  1. 5.2.2.1.

    The analyser linearization curve shall be 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. 5.2.2.2.

    The calibration gas concentration required may be obtained by means of a gas divider, diluting with purified N2 or with purified synthetic air.

  3. 5.2.2.3.

    The linearization curve shall be 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.

  4. 5.2.2.4.

    The linearization curve shall not differ by more than ± 2 per cent from the nominal value of each calibration gas.

  5. 5.2.2.5.

    From the trace of the linearization curve and the linearization 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:

    1. (a)

      Analyser and gas component;

    2. (b)

      Range;

    3. (c)

      Date of linearisation.

  6. 5.2.2.6.

    If the approval authority is satisfied that alternative technologies (e.g. computer, electronically controlled range switch, etc.) give equivalent accuracy, these alternatives may be used.