Which industry standards apply to hydrocarbon gas analysis by GC?
Hydrocarbon gas analysis is governed by international standards that define the test method, the calculation procedure, or both. The standard you need to comply with depends on the type of gas, the property you are reporting, and the regulatory or commercial framework you operate within.
Natural gas standards
ASTM D1945 is the standard test method for the analysis of natural gas by gas chromatography. It defines the GC method for measuring the composition of natural gas including methane, ethane, propane, butane, pentanes, hexanes plus, nitrogen, carbon dioxide, and oxygen.
ISO 6974 covers the determination of natural gas composition with defined uncertainty. It specifies the GC method and the calculation of measurement uncertainty for each component.
ISO 6976 covers the calculation of calorific values, density, relative density, and Wobbe Index from composition. It does not define the analytical method itself but specifies how the measured composition data is converted into physical and commercial properties. This is the standard used for custody transfer and billing calculations in many markets.
ASTM D3588 covers the calculation of heating value, compressibility factor, and specific gravity from composition data. It serves a similar function to ISO 6976 within the ASTM framework.
GPA 2172 covers the calculation of gross heating value, relative density, and compressibility factor for natural gas mixtures. It is widely used in North American gas markets.
LPG standards
ASTM D2163 is the standard test method for the analysis of LPG and propane/propylene mixtures by gas chromatography. It defines the GC method for measuring individual hydrocarbon components.
ASTM D2598 covers the calculation of certain physical properties of LPG from composition data, including vapour pressure, relative density, and specific gravity.
ASTM D2421 is a practice for the interconversion of analysis of C5 and lighter hydrocarbons to a common basis. It provides a framework for comparing results from different laboratories or methods.
How Ellutia instruments comply
The 200 Series GC is configured to produce results in compliance with the standards listed above. Column selection, detector configuration, sampling hardware, and data processing are set up to meet the method requirements of each standard. The Clarity data station software performs the property calculations automatically in compliance with the relevant calculation standards.
If you need to meet a specific standard not listed here, get in touch and we can confirm whether the 200 Series configuration covers it.