Reference number
ISO 6145-7:2018
© ISO 2026
International Standard
ISO 6145-7:2018
Gas analysis — Preparation of calibration gas mixtures using dynamic methods — Part 7: Thermal mass-flow controllers
Edition 3
2018-12

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Published (Edition 3, 2018)
This publication was last reviewed and confirmed in 2024. Therefore this version remains current.

ISO 6145-7:2018

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Abstract

ISO 6145 is a series of documents dealing with various dynamic methods used for the preparation of calibration gas mixtures. This document specifies a method for continuous preparation of calibration gas mixtures, from nominally pure gases or gas mixtures by use of thermal mass-flow controllers. The method is applicable to preparation of mixtures of non-reacting species, i.e. those which do not react with any material of construction of the flow path in the thermal mass-flow controller or the ancillary equipment.

If this method is employed for preparation of calibration gas mixtures the optimum performance is as follows: the relative expanded measurement uncertainty U, obtained by multiplying the 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 calibration gas mixture can be prepared on a continuous basis and that multi-component mixtures can be prepared as readily as binary mixtures if the appropriate number of thermal mass-flow controllers is utilized.

NOTE Gas blending systems, based upon thermal mass-flow controllers, and some including the facility of computerization and automatic control, are commercially available.

General information

  • Status
     : Published
    Publication date
     : 2018-12
    Stage
    : International Standard confirmed [90.93]
  • Edition
     : 3
    Number of pages
     : 14
  • Technical Committee :
    ISO/TC 158
    ICS :
    71.040.40 
  • RSS updates

 Amendments

Amendments are issued when it is found that new material may need to be added to an existing standardization document. They may also include editorial or technical corrections to be applied to the existing document.

Amendment 1

Correction of Formula C.4

Edition 2026

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Life cycle

Sustainable Development Goals

This standard contributes to the following Sustainable Development Goal

9
Industry, Innovation and Infrastructure

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