GB/T 27894.2-2020
Natural gas—Determination of composition and associated uncertainty by gas chromatography—Part 2: Uncertainty calculations (English Version)
- Standard No.
- GB/T 27894.2-2020
- Language
- Chinese, Available in English version
- Release Date
- 2020
- Published By
- General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
- Latest
- GB/T 27894.2-2020
- Replace
- GB/T 27894.2-2011
- Scope
- This part of GB/T27894 gives the uncertainty assessment process for the mole fraction of each component in natural gas analysis. This section is used in conjunction with GB/T 27894.1.
- Introduction
Analysis of the core content of the standard
Technical elements Type I analysis mode Type II analysis mode Sources of uncertainty Certified gas reference materials, analysis process, data fitting Random factors + linear response system errors Calculation formula Equation (1) Multi-parameter joint evaluation Equation (2)(3) Slope correction method Detector requirements FID uncertainty ≤2%, TCD ≤10% (Appendix B)
Evolution of key technologies
Main improvements compared to the 2011 version:
- New methane subtraction method (Appendix A): Calculate the uncertainty after subtraction by using equations (A.1)-(A.3)
- Optimize response factor evaluation: Clarify the normative requirements for FID/TCD relative response factors
- Introduce GLS algorithm: Generalized least squares method reduces the conservative error of multiple normalization
Implementation recommendations
Key points for laboratory operation
- Regular verification of response linearity is required when using gas chromatograph (Clause 5.3.2.4)
- For C6+ components, the successive normalization method (Equation 16) is recommended
- When calculating the expanded uncertainty, it is recommended that the inclusion factor k be 2 (corresponding to 95% confidence level)
Typical application scenarios
This standard is particularly suitable for:
- Composition analysis in LNG custody transfer measurement
- Verification of pipeline natural gas energy metering system
- Component monitoring in the development of unconventional natural gas
GB/T 27894.2-2020 Referenced Document
- ISO 6974-1:2012 Natural gas - Determination of composition and associated uncertainty by gas chromatography - Part 1: General guidelines and calculation of composition
GB/T 27894.2-2020 history
- 2020 GB/T 27894.2-2020 Natural gas—Determination of composition and associated uncertainty by gas chromatography—Part 2: Uncertainty calculations
- 2011 GB/T 27894.2-2011 Natural gas.Determination of composition with defined uncertainty by gas chromatography.Part 2:Measuring-system characteristics and statistics for processing of data
GB/T 27894.2-2020 -All Parts
GB/T 27894.1-2020 Natural gas—Determination of composition and associated uncertainty by gas chromatography—Part 1: General guidelines and calculation of composition
GB/T 27894.2-2020 Natural gas—Determination of composition and associated uncertainty by gas chromatography—Part 2: Uncertainty calculations
GB/T 27894.3-2023 Determination of the Composition of Natural Gas by Gas Chromatography and Calculation of Associated Uncertainties Part 3: Precision and Bias
GB/T 27894.4-2012 Natural gas.Determination of composition with defined uncertainty by gas chromatography.Part 4:Determination of nitrogen,carbon dioxide and C1 to C5 and C6+ hydrocarbons for a laboratory and on-line measuring system using two columns
GB/T 27894.5-2012 Natural gas-Determination of composition with defined uncertainty by gas chromatography.Part 5:Determination of nitrogen,carbon dioxideand C1 to C5and C6+hydrocarbons for a laboratory and on-line process application using thr
GB/T 27894.6-2012 Natural gas.Determination of composition with defined uncertainty by gas chromatography.Part 6:Determination of hydrogen helium oxygen nitrogen carbon dioxide and C1 to C8 hydrocarbons using three capillary columns