Traceable Reference Gas Mixtures for Sulfur-Free Natural Gas Odorants

Abstract

The first reference gas mixtures of sulfur-free natural gas odorants that are traceable to the International System of Units (SI) have been produced and their compositions validated. These mixtures, which contain methyl acrylate and ethyl acrylate at amount fractions between 1.1 and 2.1 μmol mol(-1), can be used to underpin measurements of sulfur-free odorants, which are increasingly being used to odorize natural gas in transmission networks as they have less harmful properties than traditional sulfur-containing odorants. The reference gas mixtures produced have been shown to be stable in passivated aluminum cylinders for at least 8 months and have been validated (to within 6% or less) by interlaboratory measurements at three National Measurement Institutes. The stability of methyl acrylate and ethyl acrylate in gas sampling bags has been investigated, and the challenges of analyzing 2-ethyl-3-methylpyrazine, which is used as a stabilizer in sulfur-free odorants, are also briefly discussed.

Przegląd metod przygotowania mieszanin wzorcowych dla kontroli procesu nawaniania

“…Dla uzyskania wyników sprawdzeń stężenia środka nawaniającego w gazie o ściśle określonej niepewności wyniku konieczne jest stosowanie certyfikowanych wzorców. Ich jakość może być różna, na co wpływ ma wiele czynników, spośród których zasadnicze znaczenie ma proces przygotowania i stabilizowania wzorca (ISO Guide 34: 2009;Brown et al, 2014). Z uwagi na uwarunkowania realizacji procesu nawaniania w Polsce przegląd metod otrzymywania wzorców stosowanych w tym obszarze ograniczono do mieszanin wzorcowych THT.…”

Bilateral comparison VSL-NPL on primary gas standards for the siloxane content in biomethane

“…Substantial work in the development of the primary standard gas mixtures (PSMs), needed to facilitate the production and supply of CRMs, has been undertaken [4][5][6][7]. As the specification for the silicon concentration in biomethane is very low (down to 0.1 mg m −3 [8]), and siloxanes (and other silicon-containing volatile organic compounds (VOCs)) are reactive, it is challenging to develop and maintain such PSMs. This comparison is designed to evaluate the level of compatibility [9, definition 2.47] of the PSMs maintained by National Physical Laboratory (NPL) and Van Swinden Laboratorium (VSL) for siloxanes in methane.…”