Regional comparison SIM.QM-S5 - natural gas

Abstract

Main textThe knowledge of natural gas composition is relevant for custody transfer operations. The determination of its composition is often used as the basis for the calculation of the calorific value. This report is a supplementary comparison organized for the Latin American region at SIM for components from methane to n-hexane, nitrogen, and carbon dioxide with a total of ten components. The traveling standards were obtained from an external source and checked for homogeneity and stability by CENAM before and after the measurements by participants and confirming the values under the involvement of two coordinating laboratories (CENAM and KRISS).The level of uncertainties of this comparison were not the traditional lower uncertainties for natural gas by long-established NMIs. Nevertheless, the results from the comparison are a useful official starting point for the SIM region. All results usually agree at levels higher than 0.6 % with the comparison reference value.The combination of the complexity of the samples being obtained from an external provider, the loss of performance of methods and instruments used by CENAM, and the use of traveling standards all contributed to the unexpectedly higher uncertainties of measurement results of this study. It should also be noted that some participating laboratories did not consider normalizing their results and did not apply all appropriate corrections. For the reference value, all normalized amount fractions have been used and uncertainties propagated appropriately.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).