Catalytic decomposition of S2F10 and its implications on sampling and detection from SF6-insulated equipment

The authors report the first results of a study investigating the mechanisms and rates of surface decomposition of S₂F₁₀ under various conditions. The results of this study indicate that the decomposition of S₂F₁₀ in standard sample cylinders is a problem in any attempt to determine the presence of S₂F₁₀ in SF₆-insulated equipment. It is shown that surface decomposition rates on stainless steel increase with increased water content, temperature, and surface-to-volume ratio, and with decreased gas pressure. The implications of these results for the preparation and storage of S₂F₁₀ samples are discussed. Additionally, the use of this surface decomposition mechanism to enhance the detection sensitivity of small concentrations of S₂ F₁₀ in SF₆ using a gas chromatograph/mass spectrometer (GC/MS) is investigated. Detection sensitivities of 1 p.p.m. by volume of S₂F₁₀ in SF₆ are routinely achievable using this technique