NF ISO 6145-7

NF ISO 6145-7

September 2009
Standard Cancelled

Gas analysis - Preparation of calibration gas mixtures using dynamic volumetric methods - Part 7 : thermal mass-flow controllers

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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Main informations

Collections

National standards and national normative documents

Publication date

September 2009

Number of pages

21 p.

Reference

NF ISO 6145-7

ICS Codes

71.040.40   Chemical analysis

Classification index

X20-205-7

Print number

1 - 31/08/2009

International kinship

Sumary
Gas analysis - Preparation of calibration gas mixtures using dynamic volumetric methods - Part 7 : thermal mass-flow controllers

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.

Replaced standards (1)
NF X20-211
April 1983
Published document Cancelled
Gas analysis. Preparation of calibration gas mixtures. Mass dynamic method.

Standard replaced by (1)
NF EN ISO 6145-7
April 2011
Standard Cancelled
Gas analysis - Preparation of calibration gas mixtures using dynamic volumetric methods - Part 7 : thermal mass-flow controllers

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.

Table of contents
  • Avant-propos
    iv
  • 1 Domaine d'application
    1
  • 2 Références normatives
    1
  • 3 Termes et définitions
    2
  • 4 Principe
    2
  • 5 Configuration
    2
  • 5.1 Généralités
    2
  • 5.2 Régulateur thermique de débit massique utilisant un générateur de courant constant
    2
  • 5.3 Régulateur thermique de débit massique opérant à température constante
    3
  • 6 Préparation de mélanges de gaz
    4
  • 6.1 Description du mode opératoire expérimental
    4
  • 6.2 Zone de validité
    6
  • 6.3 Conditions de fonctionnement
    7
  • 7 Calculs
    7
  • 7.1 Fraction volumique
    7
  • 7.2 Sources d'incertitude
    7
  • 7.3 Incertitude de mesure
    8
  • Annexe A (informative) Prémélanges gazeux utilisés pour la préparation de mélanges fortement dilués
    9
  • Annexe B (informative) Conseils pratiques
    10
  • Annexe C (informative) Calcul des incertitudes
    12
  • Bibliographie
    15
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