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Standard

ISO 6145-7:2009

Withdrawn

Note: Latest version: ISO 6145-7:2018

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Abstract

ISO 6145-7:2009 specifies a method for continuous production of calibration gas mixtures, containing two or more components, from pure gases or other gas mixtures by use of commercially available thermal mass-flow controllers. If this method is employed for the preparation of calibration gas mixtures, the optimum performance is as follows: the relative expanded uncertainty of measurement, U, obtained by multiplying the combined standard uncertainty by a coverage factor k = 2, is not greater than 2 %. If pre-mixed gases are used instead of pure gases, mole fractions below 10-6 can be obtained. The measurement of mass flow is not absolute and the flow controller requires independent calibration. The merits of the method are that a large quantity of the gas mixture can be prepared on a continuous basis and that multicomponent mixtures can be prepared as readily as binary mixtures if the appropriate number of thermal mass-flow controllers is utilized.

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  • Standard from ISO
  • Published:
  • Withdrawn:
  • Period for objection until:
  • Edition: 2
  • Document type: IS
  • Pages
  • Publisher: ISO
  • Distributor: ISO
  • ICS: 71.040.40
  • International TC: ISO/TC 158

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