GB/T 40704-2021Natural gas—Determination of odorant tetrahydrothiophene—On-line sampling gas chromatography method (English PDF)
天然气 加臭剂四氢噻吩含量的测定 在线取样气相色谱法
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
October 11, 2021
Implementation date
May 1, 2022
Scope
GB/T 40704-2021 is the English-translated version of 天然气 加臭剂四氢噻吩含量的测定 在线取样气相色谱法.
GB/T 40704-2021 is the Chinese national method for measuring tetrahydrothiophene, the odorant added to natural gas, directly on site with a portable gas chromatograph fitted with a thermal conductivity detector.
It sets out the principle of the method, in which the sample and a tetrahydrothiophene gas reference material are run under the same conditions and compared by peak height or peak area, together with the reagents and materials, the instrument, sampling, the measurement steps, the calculation and the precision requirements.
Helium is used as carrier gas, and the method covers contents from 5 mg/m³ to 200 mg/m³. Gas utilities and testing laboratories use it to check odorization levels in the field. It was issued on 11 October 2021 and has applied since 1 May 2022.
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Document preview — GB/T 40704-2021
National Standard of the People's Republic of China
- ICS
- 75.060
- Classification
- E 24
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- Foreword
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- 4 Principle
- 5 Reagents and materials
- 6 Portable gas chromatograph
- 7 Sampling
- 8 Measurement step
- 9 Calculation
- 10 Precision
Foreword
This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1: Structure and Drafting Rules of Standardization Documents" Drafting.
1 Scope
This document stipulates the principle of online determination of odorant tetrahydrothiophene content in natural gas using thermal conductivity detector-portable gas chromatograph, Reagents and materials, instruments, sampling, determination procedures, calculation methods and precision requirements.
This document is applicable to the determination of the content of tetrahydrothiophene in natural gas, and the measurement range is 5mg/m³~200mg/m³.
2 Normative references
The content of the following documents constitutes an indispensable clause of this document through normative references in the text. Among them, dated quotations Only the version corresponding to the date is applicable to this document; for undated reference documents, the latest version (including all amendments) is applicable to this document.
GB/T 8170 Numerical rounding rules and the expression and determination of limit values
GB/T 13609 Guidelines for Natural Gas Sampling
CJJ/T 148-2010 Technical Regulations for Odorization of Urban Gas
3 Terms and definitions
The following terms and definitions apply to this document.
3.1 Portable gas chromatograph
The gas chromatograph is small in size and equipped with a built-in carrier gas cylinder, which is easy to carry to the site for testing.
4 Principle
Representative natural gas samples and known content of tetrahydrothiophene gas standard materials, under the same operating conditions, enter the chromatographic column After separation, enter the thermal conductivity detector (TCD) to determine the content of tetrahydrothiophene. The content of tetrahydrothiophene is proportional to the peak height or peak area.
By comparing the tetrahydrothiophene peak height or peak area of the standard substance and the natural gas sample, the content of tetrahydrothiophene in the natural gas sample is obtained.
5 Reagents and materials
5.1 Carrier gas
Helium, the volume fraction is not less than 99.999%.
5.2 Gas reference materials
It is recommended to use tetrahydrothiophene gas standard material with a national standard material certification certificate with a content of about 20mg/m³.
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.
Referenced standards
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Related Standards
CJJ/T 148-2010 — Technical specification for city gas odorization
GB/T 13609-1999 — Natural Gas--Sampling guidelines
GB/T 13609-2012 — Natural gas sampling guidelines
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