GB/T 5275.7-2025Gas analysis - Preparation of calibration gas mixtures using dynamic methods - Part 7: Thermal mass-flow controllers (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents".

Drafting.

This document is Part 7 of GB/T 5275.GB/T 5275 has the following parts published.

---Preparation of Calibration Mixtures for Dynamic Gas Analysis - Part 1: General Requirements;

---Preparation of Calibration Mixtures for Dynamic Gas Analysis - Part 2: Piston Pumps;

---Preparation of Calibration Mixtures for Gas Analysis Using Dynamic Volumetric Methods, Part 4: Continuous Injection Method;

---Preparation of Calibration Mixtures for Gas Analysis Using Dynamic Volumetric Methods, Part 5: Capillary Calibrators;

---Preparation of Calibration Mixtures for Dynamic Gas Analysis, Part 6: Critical Flow Through Sharp Orifices;

---Preparation of Calibration Mixtures for Dynamic Gas Analysis - Part 7: Thermal Mass Flow Controllers;

---Preparation of Calibration Mixtures for Gas Analysis Using Dynamic Volumetric Methods, Part 8: Diffusion Methods;

---Preparation of Calibration Mixtures for Gas Analysis Using Dynamic Volumetric Methods, Part 9: Saturation Method;

---Preparation of Calibration Mixtures for Gas Analysis Using Dynamic Volumetric Methods, Part 10: Permeation Method;

---Preparation of Calibration Mixtures by Dynamic Volumetric Methods for Gas Analysis, Part 11: Electrochemical Generation Methods.

This document replaces GB/T 5275.7-2014 "Preparation of Calibration Mixtures by Dynamic Volumetric Method for Gas Analysis - Part 7: Thermal Mass Analyzer".

Compared with GB/T 5275.7-2014, the main technical changes in the "Flow Controller" standard, apart from structural adjustments and editorial modifications, are as follows.

---Corrected a bug in the dilution ratio calculation (see 7.1, 6.1 in the 2014 version);

---Added restrictions on volume fraction calculations (see 8.1);

---Added the method for verifying the composition of the calibration gas mixture prepared by the mixing system (see 8.3).

This document is equivalent to ISO 6145-7:2018 "Gas analysis - Dynamic methods - Preparation of calibration mixtures - Part 7: Thermal mass spectrometry".

Flow controller.

The following minimal editorial changes have been made to this document.

---The uncertainty figures have been corrected, and the ± sign before the uncertainty figures has been removed (see 7.1);

---The reference 6.1 in note B.1 of Appendix B is corrected to 7.1;

---Corrected the representation of phiA in Appendix C and the editorial errors in the formula for calculating the relative standard uncertainty (see Appendix C).

Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.

This document was proposed by the China Petroleum and Chemical Industry Federation.

This document is under the jurisdiction of the National Technical Committee on Gas Standardization (SAC/TC206).

Introduction

Dynamic methods are a major class of important methods for preparing calibration gas mixtures, and ISO has specifically developed the ISO 6145 series of standards for this purpose.

(ISO 6145-3 is obsolete).

GB/T 5275 (all parts) is equivalent to the ISO 6145 series of standards. Due to its length, ISO 6145 is divided into 11 parts.

GB/T 5275 is consistent with ISO 6145, and is also divided into 11 parts. Since ISO 6145-3 has been repealed, GB/T 5275 Part 3...

Some parts are also correspondingly missing. GB/T 5275 (all parts) specifies the general requirements for the preparation of calibration mixed gases by dynamic methods, and specifically specifies...

The principles, main equipment, preparation precautions, and preparation results of nine methods for preparing calibration mixed gases, including the thermal mass flow controller method, are defined.

The technical requirements for calculating the component content (volume fraction) and evaluating the uncertainty of the calibration gas mixture must be met to ensure the accuracy of the prepared calibration gas mixture.

Improve the quality of the mixed gas and enhance the preparation level of the mixed gas for calibration.

GB/T 5275 (all parts) is intended for use by trained and experienced professionals.

GB/T 5275 consists of ten parts.

---Part 1: General Requirements. This section specifies the basic information and applicability of each preparation method, operational precautions for dynamic preparation systems, etc.

The calibration methods for dynamic preparation systems, the calculation and verification methods of the content and uncertainty of each component in the calibration mixed gas, etc.

This component forms the basis for the other nine parts. Its purpose is to provide a framework for the rational selection of one or more calibration gas mixture preparation methods.

Basic information, and linking the methods described in these nine parts with national measurement standards to ensure the composition of the prepared gas mixture.

Metrological traceability.

---Part 2: Piston Pumps. The purpose is to provide a method for the continuous preparation of calibration mixtures from pure gases and mixed gases using a piston pump.

The method, the calculation method of the content of each component in the prepared calibration gas mixture, and the uncertainty evaluation method.

---Part 4: Continuous Injection Method. The purpose is to provide a method for continuously injecting pure gas or a gas mixture into a balanced gas via a syringe.

A method for continuously preparing calibration gas mixtures by means of standard components, and a method for calculating the content of each component in the prepared calibration gas mixture.

Calculation methods and uncertainty assessment methods.

---Part 5: Capillary Calibrator. The purpose is to provide a device that utilizes single or multiple capillary combinations to calibrate pure gas or mixed gas.

A method for continuously preparing calibration mixed gases, and a method for calculating the content of each component in the prepared calibration mixed gas.

And the uncertainty assessment method.

---Part 6: Critical Flow Sharp Orifice. The purpose is to provide a method for the continuous preparation of calibrated mixtures from pure gas or gas mixtures using a critical flow sharp orifice.

The gas method, the calculation method of the content of each component in the prepared calibration gas mixture, and the uncertainty assessment method.

---Part 7: Thermal Mass Flow Controllers. The purpose is to provide a method for using thermal mass flow controllers to handle pure gas or gas mixtures.

A method for continuously preparing calibration mixed gases, and a method for calculating the content of each component in the prepared calibration mixed gases.

Uncertainty assessment method.

---Part 8: Diffusion Method. The purpose is to provide a method for the continuous preparation of calibration mixtures from pure or mixed gases using diffusion.

Methods, calculation methods for the content of each component in the prepared calibration gas mixture, and uncertainty assessment methods.

---Part 9: Saturation Method. The purpose is to provide a method for the continuous preparation of calibration mixtures from one or more easily condensable gases using the saturation method.

The method for preparing a calibration gas mixture, the calculation method for the content of each component in the prepared calibration gas mixture, and the uncertainty assessment method.

---Part 10: Permeation Method. The purpose is to provide a method for the continuous preparation of calibration mixtures from pure or mixed gases using the permeation method.

Methods, calculation methods for the content of each component in the prepared calibration gas mixture, and uncertainty assessment methods.

---Part 11: Electrochemical Generation Method. The aim is to provide a method for the continuous preparation of calibration mixtures from pure or mixed gases using electrochemical methods.

The method for preparing a calibration gas mixture, the calculation method for the content of each component in the prepared calibration gas mixture, and the uncertainty assessment method.

Preparation of Calibration Mixtures by Dynamic Gas Analysis Part 7: Thermal Mass Flow Controller

1 Scope

GB/T 5275 is a series of documents for various dynamic methods for preparing calibration gas mixtures. This document describes the use of thermal mass spectrometry.

A flow rate controller, and a method for continuously preparing a calibration gas mixture using pure gas or a gas mixture. This document applies to components where no reaction occurs.

A mixed gas, meaning that the components do not react with the materials that make up the flow path of a thermal mass flow controller or auxiliary equipment.

The best-in-class levels achievable with the calibration gas mixtures prepared using the methods described in this document are as follows. relative measurement expanded uncertainty.

(U is obtained by multiplying the standard uncertainty by the coverage factor k=2) and is no greater than 2%.

Using premixed gas instead of pure gas can produce gas mixtures with a mole fraction lower than 10-6. The measurement of mass flow rate is not absolute.

Yes, the flow controller needs to be calibrated separately.

The advantage of the method described in this document is that it can continuously prepare large quantities of calibration gas mixtures, provided that an appropriate amount of thermal mass flow rate is used.

The controller allows for the convenient preparation of multi-component mixed gases, much like the preparation of binary mixed gases.

Note. Gas mixing systems based on thermal mass flow controllers, including some computer processing and automatic control devices, are available on the market.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.

For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.

This document.

ISO 6143 Gas analysis calibration - Determination and verification of the composition of gas mixtures (Gas analysis-Comparison) Note. GB/T 10628-2008 Gas analysis calibration - Determination and verification of the composition of gas mixtures (ISO 6143:2001, IDT) ISO 6145-1 Gas analysis—Dynamic methods for preparing calibration mixtures—Part 1: General methods (Gasanalysis-Prepare-Note. GB/T 5275.1-2024 Gas analysis - Dynamic methods for preparing calibration mixed gases - Part 1: General requirements (ISO 6145-1:2019, IDT) ISO 7504 Gas Analysis Vocabulary Note. GB/T 14850-2020 Glossary of Gas Analysis (ISO 7504:2015, IDT) ISO 12963 Gas analysis—Determination of composition of gas mixtures—Comparative method based on single-point and two-point calibration (Gasanalysis-Com-calibration) Note. GB/T 45133-2025 Gas analysis - Determination of composition of gas mixtures based on single-point and two-point comparison methods (ISO 12963:2017, MOD) mentofpuritydata) Note. GB/T 38521-2025 Gas analysis - Purity analysis and processing of purity data (ISO 19229:2019, IDT)

3 Terms and Definitions

The terms and definitions defined in ISO 7504 apply to this document.