EN ISO 6145-11:2008

Foreword
Introduction
1 Scope
2 Normative references
3 Procedure
  3.1 Principle
  3.2 Complementary gas
  3.3 Electrolytic systems for gas generation
  3.4 Apparatus
      3.4.1 Cell construction
      3.4.2 Current supply and gas flow control
  3.5 Gas mixture preparation
      3.5.1 Complementary gas
      3.5.2 Voltage supply
      3.5.3 Calculation of gas mixture content
4 Uncertainty evaluation
  4.1 Introduction
  4.2 Sources of uncertainty
      4.2.1 Complementary gas flow
      4.2.2 Gas generation
      4.2.3 Absorption of generated gas in the cell
            electrolyte
      4.2.4 Effect of moisture content
      4.2.5 Effect of temperature
      4.2.6 Purity of electrolytic chemicals
      4.2.7 Impurities in complementary gas
  4.3 Uncertainty of volume fraction
5 Electrochemical cell design
Annex A (informative) Example of a commercial electrochemical
        cell
Annex B (informative) Schematics of electrolytic cells used
        for gas generation
Annex C (informative) Schematic of electrical supply to gas
        generation cell
Annex D (informative) Decomposition voltages of solutions
        between smooth platinum electrodes
Bibliography

ISO 6145-11:2005 specifies a method for the preparation of calibration gas mixtures by using electrochemical generation of a calibration component and introduction into a complementary gas flow. By alteration of the gas flow or the charge passed through the cell electrolyte, it is possible to change the composition of the gas mixture. The relative expanded uncertainty of the calibration gas content, U, obtained by multiplying the relative combined standard uncertainties by a coverage factor, k = 2, is not greater than 5 %.The method described in ISO 6145-11:2005 is intended to be applied to the preparation of calibration gas mixtures in the volume fraction ranges (0,1 to 250) x 10-6.