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BS ISO 6145-2:2014

Current
Current

The latest, up-to-date edition.

Gas analysis. Preparation of calibration gas mixtures using dynamic methods Piston pumps
Available format(s)

Hardcopy , PDF

Language(s)

English

Published date

31-07-2014

Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols
5 Principle and equipment
6 Calibration gas mixture preparation
7 Calculation of volume fractions and associated
  uncertainty evaluation
8 Gas mixture composition verification
Annex A (normative) - Amount-of-substance fractions
Annex B (informative) - Uncertainty evaluation of the
        gas mixture composition
Annex C (informative) - Gas mixture verification
Annex D (informative) - Numerical example
Bibliography

Defines a method and preparation system using piston pumps. The mixture composition and its associated uncertainty are based on calibration of the piston pumps by dimensional measurements.

ISO6145 comprises a series of International Standards dealing with various dynamic methods used for the preparation of calibration gas mixtures. This part of ISO6145 describes a method and preparation system using piston pumps. The mixture composition and its associated uncertainty are based on calibration of the piston pumps by dimensional measurements.

The calibration gas mixtures prepared using this method consist of two or more components, prepared from pure gases or other gas mixtures using gas-mixing pumps. Such gas-mixing pumps contain at least two piston pumps, each driven with a defined ratio of strokes, and appropriate accessories for gas feeding and mixture homogenization.

This part of ISO6145 is applicable only to mixtures of gaseous or totally vaporized components including corrosive gases, as long as these components neither react with each other nor with the wetted surfaces of the mixing pump. The use of gas mixtures as parent gases is covered as well. Multi-component gas mixtures and multi-step dilution procedures are included in this International Standard as they are considered to be special cases of the preparation of two-component mixtures.

This part of ISO6145 describes a method of preparing calibration gas mixtures whose composition is expressed in volume fractions. The necessary equations and associated uncertainty evaluation to express the gas composition in amount–of–substance fractions are given in AnnexA.

With this method, provided that sufficient quality assurance and control measures are taken, calibration gas mixtures can be prepared with a relative expanded uncertainty of 0,5% (coverage factor k=2) in the volume fraction. Numerical examples showing that under specified conditions smaller uncertainties are attainable are given in AnnexesB through D.

Using this method, dilution ratios of 1:10 000 can be achieved in discrete increments. Lower fractions (down to 1×10−8) can be achieved by multi-stage dilution or by the use of gas mixtures as input gases. Final mixture flow rates of 5l/h to 500l/h can be realized depending on the equipment used.

Committee
PTI/15
DevelopmentNote
Supersedes 97/125572 DC. (06/2005) Supersedes 13/30214514 DC. (08/2014)
DocumentType
Standard
Pages
40
PublisherName
British Standards Institution
Status
Current
Supersedes

Standards Relationship
ISO 6145-2:2014 Identical

ISO/IEC Guide 99:2007 International vocabulary of metrology Basic and general concepts and associated terms (VIM)
ISO 6143:2001 Gas analysis — Comparison methods for determining and checking the composition of calibration gas mixtures
ISO 6142:2001 Gas analysis Preparation of calibration gas mixtures Gravimetric method
ISO 14912:2003 Gas analysis — Conversion of gas mixture composition data
ISO 7504:2015 Gas analysis Vocabulary
ISO/IEC Guide 98-3:2008 Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)

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