BS EN ISO 6145-6:2017
$167.15
Gas analysis. Preparation of calibration gas mixtures using dynamic methods – Critical flow orifices
| Published By | Publication Date | Number of Pages |
| BSI | 2017 | 34 |
This document specifies a method for the dynamic preparation of calibration gas mixtures containing at least two gases (usually one of them is a complementary gas) from pure gases or gas pre-mixtures using critical flow orifices systems.
The method applies principally to the preparation of mixtures of non-reactive gases that do not react with any of the materials forming the gas circuit inside the critical flow orifices system or auxiliary equipment. It has the merit of allowing multi-component mixtures to be prepared as readily as binary mixtures if an appropriate number of critical flow orifices are used.
By selecting appropriate combinations of critical flow orifices, a dilution ratio of 1 × 104 is achievable.
Although it is more particularly applicable to the preparation of gas mixtures at atmospheric pressure, the method also offers the possibility of preparing calibration gas mixtures at pressures greater than atmospheric. The upstream pressure will need to be at least two times higher than downstream pressure.
The range of flow rates covered by this document extends from 1 ml/min to 10 l/min.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | National foreword |
| 4 | European foreword |
| 5 | Foreword |
| 6 | 1 Scope 2 Normative references 3 Terms and definitions |
| 9 | 4 Symbols |
| 10 | 5 Principle |
| 11 | 6 Calculation of mass flow rate and volume flow rate 6.1 General |
| 12 | 6.2 Calculation under ideal conditions 6.2.1 Calculation of mass flow rate 6.2.2 Calculation of volume flow rates |
| 13 | 6.3 Calculation of mass flow rate using flow calibration with pure nitrogen |
| 14 | 6.4 Flow rate uncertainty calculation 6.4.1 General 6.4.2 Sources of uncertainty |
| 15 | 6.4.3 Uncertainty estimation 7 Calculation of amount of substance fraction and volume fraction and associated uncertainty evaluation 7.1 General 7.2 Amount of substance fraction calculation and associated uncertainty 7.2.1 Case of gases with purity ≥ 99,99 % |
| 18 | 7.2.2 Case of pre-mixtures |
| 20 | 7.3 Remarks about uncertainty for the amount fraction 8 Application to the preparation of gas mixtures 8.1 Example of a mixing system |
| 21 | 8.2 Conditions of operation |
| 22 | 9 Calibration and verification 9.1 General 9.2 Calibration of the mixing system in the flow rate 9.3 Calibration of the mixing system with gas mixtures for a specific gas and concentration 9.4 Verification of the mixing system |
| 24 | Annex A (informative) Example of calculation of isentropic coefficient, viscosity and critical flow coefficient |
| 26 | Annex B (informative) Calculation of mass and volume flow rates under real conditions |
| 28 | Annex C (informative) Example of flow calculation for toroidal critical flow orifices under ideal and real conditions |
| 30 | Annex D (informative) Calculation of mass flow rate using flow calibration with pure nitrogen: examples |
| 32 | Bibliography |
