NF EN ISO 6145-4
Gas analysis - Preparation of calibration gas mixtures using dynamic volumetric methods - Part 4 : continuous syringe injection method
ISO 6145-4:2004 specifies a method for continuous production of calibration gas mixtures, containing two or more components, from pure gases or other gas mixtures by continuous injection of the calibration component(s) into a complementary gas stream by means of a syringe. If pre-mixed gases are used instead of pure gases (see Annex A), much lower volume fractions can be obtained. The volume flow rates, from which the volume fractions are determined, can be calculated from the individual flow rates and can be independently measured by a suitable method given in ISO 6145-1. The merits of the method are that a substantial quantity of the gas mixture can be prepared on a continuous basis and that multi-component mixtures can be prepared almost as readily as binary mixtures if the appropriate number of syringes is utilized, or if the syringe already contains a multi-component mixture of known composition. This method also provides a convenient means for increasing the volume fraction of the calibration component in the mixture in small steps. It is therefore a useful method for evaluation of other characteristics of gas analysers, such as minimum detection limit and dead zone, as well as accuracy. The relative expanded uncertainty in the volume fraction obtainable for a binary mixture (at a coverage factor of 2) is 5 % and the range of applicability is 10-5 to 10-2.
ISO 6145-4:2004 specifies a method for continuous production of calibration gas mixtures, containing two or more components, from pure gases or other gas mixtures by continuous injection of the calibration component(s) into a complementary gas stream by means of a syringe.
If pre-mixed gases are used instead of pure gases (see Annex A), much lower volume fractions can be obtained. The volume flow rates, from which the volume fractions are determined, can be calculated from the individual flow rates and can be independently measured by a suitable method given in ISO 6145-1.
The merits of the method are that a substantial quantity of the gas mixture can be prepared on a continuous basis and that multi-component mixtures can be prepared almost as readily as binary mixtures if the appropriate number of syringes is utilized, or if the syringe already contains a multi-component mixture of known composition. This method also provides a convenient means for increasing the volume fraction of the calibration component in the mixture in small steps. It is therefore a useful method for evaluation of other characteristics of gas analysers, such as minimum detection limit and dead zone, as well as accuracy. The relative expanded uncertainty in the volume fraction obtainable for a binary mixture (at a coverage factor of 2) is 5 % and the range of applicability is 10-5 to 10-2.
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1 Domaine d'application1
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2 Références normatives1
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3 Principe1
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4 Application à la préparation des mélanges de gaz2
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4.1 Description du mode opératoire expérimental2
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4.2 Domaine de validité4
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4.3 Conditions de fonctionnement4
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5 Expression des résultats4
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5.1 Fraction volumique4
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5.2 Sources d'incertitude4
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5.3 Incertitude de la fraction volumique5
- Annexe A (informative) Prémélanges gazeux utilisés pour la préparation de mélanges fortement dilués6
- Annexe B (informative) Exemple d'appareillage pour la préparation de mélanges de gaz pour étalonnage7
- Annexe C (informative) Conseils pratiques9
- Annexe D (informative) Exemple de détermination de l'incertitude de la concentration d'un mélange de gaz pour étalonnage préparé par la méthode d'injection continue12
- Bibliographie15
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