Sulfur hexafluoride (SF6) is widely used as a tracer gas because of its detectability at low concentrations. This attribute of SF6 allows the quantification of both small-scale flows, such as leakage, and large-scale flows, such as atmospheric currents. SF6's high detection sensitivity also facilitates greater usage efficiency and lower operating cost for tracer deployments by reducing quantity requirements. The detectability of SF6 is produced by its high molecular electronegativity. This property provides a high potential for negative ion formation through electron capture thus naturally translating to selective detection using negative ion chemical ionization mass spectrometry (NCI-MS). This paper investigates the potential of using gas chromatography (GC) with NCI-MS for the detection of SF6. The experimental parameters for an ultra-trace SF6 detection method utilizing minimal customizations of the analytical instrument are detailed. A method for the detection of parts per trillion (ppt) level concentrations of SF6 for the purpose of underground ventilation tracer gas analysis was successfully developed in this study. The method utilized a Shimadzu gas chromatography with negative ion chemical ionization mass spectrometry system equipped with an Agilent J&W HP-porous layer open tubular column coated with an alumina oxide (Al2O3) S column. The method detection limit (MDL) analysis as defined by the Environmental Protection Agency of the tracer data showed the method MDL to be 5.2 ppt.
2016): Field test of a perfluoromethylcyclohexane (PMCH) permeation plug release vessel (PPRV) in an underground longwall mine, Mining Technology To link to this article: http://dx.Perfluoromethylcyclohexane (PMCH) was released in a Midwestern underground longwall mine in the United States using a PMCH permeation plug release vessel (PPRV). The operators of this mine graciously allowed full access to an active longwall panel at two points in time to perform the test. This paper presents a study designed to determine the feasibility of using a PPRV in an underground mine environment for tracer gas studies. The results of this study showed that the PPRV is a feasible tracer delivery system for releasing PMCH at mine scale. Some of the advantages afforded by the PPRV over traditional release techniques are also highlighted.
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