What is ISO 6975 - Extended analysis of components of natural gas using the Gas chromatographic method about?
ISO 6975 describes the specifications for the quantitative analysis of the following components of natural gas: helium, hydrogen, argon, oxygen, nitrogen, carbon dioxide, saturated hydrocarbons from C1 to C5, hydrocarbon fractions from C6 upwards, and aromatic compounds as benzene and toluene.
It is not possible to make unambiguous identifications of hydrocarbons above C6. Even where “spiking” a gas mixture with known components shows where they elute, it cannot be stated with certainty that such a component is the only one with that retention time. Unidentified components are classified according to the carbon number which the analysis indicates to be appropriate. While this is a necessary simplification, it does allow a reasonable quantitative value to be obtained.
This method is intended for use in situations where the hexanes plus compositional breakdown and/or the complete analysis is desired.
Gases which have been treated for transmission are unlikely to contain detectable levels of hydrocarbons above C12. Samples taken from nearer the well head, before the gas has reached gas treatment plants, may contain hydrocarbons to C16 or above.
Note 1: This method is not intended for the determination of oxygen compounds (water vapour, methanol, glycols) or sulfur compounds.
Note 2: The method is not intended for dense phase gases whose pressure exceeds the cricondebar (critical condensation pressure), or for gas samples containing any measurable hydrocarbon condensate, liquid water or process fluid such as methanol or glycols (see ISO 6570-1 and ISO 10715).
Who is ISO 6975 - Extended analysis of components of natural gas using the Gas chromatographic method for?
ISO 6975 on extended analysis of components of natural gas using the Gas chromatographic method gas is useful for:
- Natural gas industry
- Testing laboratories
- Research institutes
- Hydrocarbon analysis agencies
Why should you use ISO 6975 - Extended analysis of components of natural gas using the Gas chromatographic method ?
ISO 6975 describes the specifications that an accurate method for the complete and extended analysis of natural gas shall fulfill.
The analytical methods specified in ISO 6975 involve the injection of natural gas onto packed or open tubular (capillary) columns in one or more gas chromatographs. The components coming off the columns are detected by a thermal conductivity detector (TCD) or flame ionization detector (FID).
Compared to other analytical methods, the extended gas-chromatographic analysis as specified in ISO 6975 supplies considerable knowledge of the individual components in the natural-gas mixture. This allows quantitative measurement of particular components in the C6+ fraction and calculation of physical properties. Although the higher hydrocarbons influence physical properties such as calorific values and density by less than 0,3 % and 0,004 %, respectively, knowledge of them is required for the evaluation of the pseudo-values for the C6+ fraction.
In addition, vapor phase equilibrium calculations often require detailed composition data, especially of hydrocarbons with carbon numbers higher than 6.
The simultaneous determination of benzene and other aromatics is needed for gas consumers using natural gas as a chemical feedstock since these components can interfere in some processes.
