Sulfur hexafluoride#Dielectric medium

{{See also|Fluorochemical industry}}

Sulfur hexafluoride on Earth exists primarily as a synthetic industrial gas, but has also been found to occur naturally.{{cite journal |author=Busenberg, E. and Plummer, N. |title=Dating young groundwater with sulfur hexafluoride: Natural and anthropogenic sources of sulfur hexafluoride |journal=Water Resources Research |publisher=American Geophysical Union |volume=36 |pages=3011–3030 |year=2000 |issue=10 |url=https://pubs.er.usgs.gov/publication/70022588#:~:text=Sulfur%20hexafluoride%20(SF6)%20is,during%20the%20past%2040%20years |doi=10.1029/2000WR900151 |bibcode=2000WRR....36.3011B |doi-access=free}}

{{chem|SF|6}} can be prepared from the elements through exposure of Sulfur to fluorine. This was the method used by the discoverers Henri Moissan and Paul Lebeau in 1901. Some other sulfur fluorides are cogenerated, but these are removed by heating the mixture to disproportionate any Disulfur decafluoride (which is highly toxic) and then scrubbing the product with NaOH to destroy remaining Sulfur tetrafluoride.{{Clarify|reason=How do you scrub a gas with a solid?|date=June 2024}}

Alternatively, using bromine, sulfur hexafluoride can be synthesized from SF₄ and CoF₃ at lower temperatures (e.g. 100 °C), as follows:{{cite conference|last1=Winter |first1=R. W. |last2=Pugh |first2=J. R. |last3=Cook |first3=P. W. |date=January 9–14, 2011 |title=SF₅Cl, SF₄ and SF₆: Their Bromine−facilitated Production & a New Preparation Method for SF₅Br |work=20th Winter Fluorine Conference}}

{{block indent|2 CoF₃ + SF₄ + [Br₂] → SF₆ + 2 CoF₂ + [Br₂]}}

There is virtually no reaction chemistry for {{chem|SF|6}}. A main contribution to the inertness of SF₆ is the steric hindrance of the sulfur atom, whereas its heavier group 16 counterparts, such as SeF₆ are more reactive than SF₆ as a result of less steric hindrance.{{cite book |author1=Duward Shriver |author2=Peter Atkins |title=Inorganic Chemistry |year=2010 |publisher=W. H. Freeman |pages=409 |isbn=978-1429252553 }} It does not react with molten sodium below its boiling point,{{cite book |title=Advanced Inorganic Chemistry: Volume II |edition=12th |first1=Gurdeep |last1=Raj |publisher=GOEL Publishing House |year=2010 |page=160 |url=https://books.google.com/books?id=qxRhA3MZg6AC}} [https://books.google.com/books?id=qxRhA3MZg6AC&pg=PA160 Extract of page 160] but reacts exothermically with lithium. As a result of its inertness, {{chem|SF|6}} has an atmospheric lifetime of around 3200 years, and no significant environmental sinks other than the ocean.{{Cite journal |last1=Stöven |first1=T. |last2=Tanhua |first2=T. |last3=Hoppema |first3=M. |last4=Bullister |first4=J. L. |date=2015-09-18 |title=Perspectives of transient tracer applications and limiting cases |url=https://os.copernicus.org/articles/11/699/2015/ |journal=Ocean Science |language=en |volume=11 |issue=5 |pages=699–718 |doi=10.5194/os-11-699-2015 |doi-access=free |bibcode=2015OcSci..11..699S |issn=1812-0792}}

By 2000, the electrical power industry is estimated to use about 80% of the sulfur hexafluoride produced, mostly as a gaseous dielectric medium.{{cite journal |author1=Constantine T. Dervos |author2=Panayota Vassilou |title=Sulfur Hexafluoride: Global Environmental Effects and Toxic Byproduct Formation |journal=Journal of the Air & Waste Management Association |year=2000 |volume=50 |issue=1 |pages=137–141 |publisher=Taylor and Francis|doi=10.1080/10473289.2000.10463996|pmid=10680375 |s2cid=8533705 |doi-access=free |bibcode=2000JAWMA..50..137D }} Other main uses as of 2015 included a silicon etchant for semiconductor manufacturing, and an inert gas for the casting of magnesium.{{cite journal |author1=Deborah Ottinger |author2=Mollie Averyt |author3=Deborah Harris |title=US consumption and supplies of sulphur hexafluoride reported under the greenhouse gas reporting program |journal=Journal of Integrative Environmental Sciences |year=2015 |volume=12 |issue=sup1 |pages=5–16 |publisher=Taylor and Francis|doi=10.1080/1943815X.2015.1092452|doi-access=free }}

{{chem|SF|6}} is used in the electrical industry as a gaseous dielectric medium for high-voltage sulfur hexafluoride circuit breakers, switchgear, and other electrical equipment, often replacing oil-filled circuit breakers (OCBs) that can contain harmful polychlorinated biphenyls (PCBs). {{chem|SF|6}} gas under pressure is used as an insulator in gas insulated switchgear (GIS) because it has a much higher dielectric strength than air or dry nitrogen. The high dielectric strength is a result of the gas's high electronegativity and density. This property makes it possible to significantly reduce the size of electrical gear. This makes GIS more suitable for certain purposes such as indoor placement, as opposed to air-insulated electrical gear, which takes up considerably more room.

Gas-insulated electrical gear is also more resistant to the effects of pollution and climate, as well as being more reliable in long-term operation because of its controlled operating environment. Exposure to an arc chemically breaks down {{chem|SF|6}} though most of the decomposition products tend to quickly re-form {{chem|SF|6}}, a process termed "self-healing".{{citation | url= http://www.weidmann-solutions.cn/zhenduan/sulfur_hexaflouride.pdf | last1= Jakob | first1= Fredi | last2= Perjanik | first2= Nicholas | title= Sulfur Hexafluoride, A Unique Dielectric | publisher= Analytical ChemTech International, Inc. | url-status= live | archive-url= https://web.archive.org/web/20160304040552/http://www.weidmann-solutions.cn/zhenduan/sulfur_hexaflouride.pdf | archive-date= 2016-03-04 }} Arcing or corona can produce disulfur decafluoride (Disulfur decafluoride), a highly toxic gas, with toxicity similar to phosgene. {{chem|S|2|F|10}} was considered a potential chemical warfare agent in World War II because it does not produce lacrimation or skin irritation, thus providing little warning of exposure.

{{chem|SF|6}} is also commonly encountered as a high voltage dielectric in the high voltage supplies of particle accelerators, such as Van de Graaff generators and Pelletrons and high voltage transmission electron microscopes.

Alternatives to {{chem|SF|6}} as a dielectric gas include several fluoroketones.{{cite web |url=http://cired.net/publications/cired2015/papers/CIRED2015_0587_final.pdf |title=Archived copy |access-date=2017-10-12 |url-status=live |archive-url=https://web.archive.org/web/20171012150303/http://cired.net/publications/cired2015/papers/CIRED2015_0587_final.pdf |archive-date=2017-10-12 }}{{cite book|date=1 June 2015|pages=379–383|via=IEEE Xplore|doi=10.1109/ICACACT.2014.7223577|chapter=SF₆ alternative development for high voltage switchgears|last1=Kieffel|first1=Yannick|last2=Biquez|first2=Francois|title=2015 IEEE Electrical Insulation Conference (EIC) |isbn=978-1-4799-7352-1|s2cid=15911515}} Compact GIS technology that combines vacuum switching with clean air insulation has been introduced for a subset of applications up to 420 kV.{{cite web |url=https://www.siemens-energy.com/global/en/offerings/power-transmission/innovation/blue-high-voltage-products.html |title=Sustainable switchgear technology for a CO₂ neutral future |publisher=Siemens Energy |date=2020-08-31 |accessdate=2021-04-27}}

{{chem|SF|6}} is used to provide a tamponade or plug of a retinal hole in retinal detachment repair operations{{cite book |author1=Daniel A. Brinton |author2=C. P. Wilkinson |title=Retinal detachment: principles and practice |pages=183 |year=2009 |publisher=Oxford University Press |isbn=978-0199716210 }} in the form of a gas bubble. It is inert in the vitreous chamber.{{cite book |author=Gholam A. Peyman, M.D., Stephen A. Meffert, M.D., Mandi D. Conway |title=Vitreoretinal Surgical Techniques |pages=157 |year=2007 |publisher=Informa Healthcare |isbn=978-1841846262 }} The bubble initially doubles its volume in 36 hours due to oxygen and nitrogen entering it, before being absorbed in the blood in 10–14 days.{{cite journal

| last1 = Hilton | first1 = G. F.

| last2 = Das | first2 = T.

| last3 = Majji | first3 = A. B.

| last4 = Jalali | first4 = S.

| title = Pneumatic retinopexy: Principles and practice

| journal = Indian Journal of Ophthalmology

| volume = 44

| issue = 3

| pages = 131–143

| year = 1996

| pmid = 9018990

}}

{{chem|SF|6}} is used as a contrast agent for ultrasound imaging. Sulfur hexafluoride microbubbles are administered in solution through injection into a peripheral vein. These microbubbles enhance the visibility of blood vessels to ultrasound. This application has been used to examine the vascularity of tumours.{{cite journal

|vauthors=Lassau N, Chami L, Benatsou B, Peronneau P, Roche A | title=Dynamic contrast-enhanced ultrasonography (DCE-US) with quantification of tumor perfusion: a new diagnostic tool to evaluate the early effects of antiangiogenic treatment

| journal=Eur Radiol

| volume=17

| issue=Suppl. 6

| pages=F89–F98

| date=December 2007

| pmid=18376462

| doi=10.1007/s10406-007-0233-6

| s2cid=42111848

}} It remains visible in the blood for 3 to 8 minutes, and is exhaled by the lungs.{{cite web|url=https://www.ema.europa.eu/documents/product-information/sonovue-epar-product-information_en.pdf|title=SonoVue, INN-sulphur hexafluoride - Annex I - Summary of Product Characteristics|website=European Medicines Agency|access-date=2019-02-24}}

Sulfur hexafluoride was the tracer gas used in the first roadway air dispersion model calibration; this research program was sponsored by the U.S. Environmental Protection Agency and conducted in Sunnyvale, California on U.S. Highway 101.{{cite web|url=http://www.eoearth.org/article/Air_pollution_line_source?topic=49506 |title=Air pollution line source |date=September 10, 2011 |author=C Michael Hogan |publisher=Encyclopedia of Earth |access-date=22 February 2013 |url-status=dead|archive-url=https://web.archive.org/web/20130529064051/http://www.eoearth.org/article/Air_pollution_line_source?topic=49506 |archive-date=29 May 2013 }} Gaseous {{chem|SF|6}} is used as a tracer gas in short-term experiments of ventilation efficiency in buildings and indoor enclosures, and for determining infiltration rates. Two major factors recommend its use: its concentration can be measured with satisfactory accuracy at very low concentrations, and the Earth's atmosphere has a negligible concentration of {{chem|SF|6}}.

Sulfur hexafluoride was used as a non-toxic test gas in an experiment at St John's Wood tube station in London, United Kingdom on 25 March 2007.{{cite news |title='Poison gas' test on Underground |url=http://news.bbc.co.uk/1/hi/england/london/6492501.stm |date=25 March 2007 |work=BBC News |access-date=22 February 2013 |url-status=live |archive-url=https://web.archive.org/web/20080215005754/http://news.bbc.co.uk/1/hi/england/london/6492501.stm |archive-date=15 February 2008 }} The gas was released throughout the station, and monitored as it drifted around. The purpose of the experiment, which had been announced earlier in March by the Secretary of State for Transport Douglas Alexander, was to investigate how toxic gas might spread throughout London Underground stations and buildings during a terrorist attack.

Sulfur hexafluoride is also routinely used as a tracer gas in laboratory fume hood containment testing. The gas is used in the final stage of ASHRAE 110 fume hood qualification. A plume of gas is generated inside of the fume hood and a battery of tests are performed while a gas analyzer arranged outside of the hood samples for SF₆ to verify the containment properties of the fume hood.

It has been used successfully as a transient tracer in oceanography to study diapycnal mixing and air-sea gas exchange.{{cite journal|last=Fine|first=Rana A.|author-link=Rana Fine|date=2010-12-15|title=Observations of CFCs and SF6 as Ocean Tracers|url=https://www.annualreviews.org/doi/10.1146/annurev.marine.010908.163933|journal=Annual Review of Marine Science|volume=3|issue=1|pages=173–195|doi=10.1146/annurev.marine.010908.163933|pmid=21329203|issn=1941-1405}} The concentration of sulfur hexafluoride in seawater (typically on the order of femtomoles per kilogramJ.L. Bullister and T. Tanhua, 2010. "Sampling and measurement of chlorofluorocarbons and sulfur hexafluoride in seawater". IOCCP Report No. 14. http://www.go-ship.org/HydroMan.html) has been classified by the international oceanography community as a "level one" measurement, denoting the highest priority data for observing ocean changes.{{Cite web |title=GO-SHIP Data Requirements |url=http://www.go-ship.org/DatReq.html |access-date=2025-01-30 |website=www.go-ship.org}}

• The magnesium industry uses {{chem|SF|6}} as an inert "cover gas" to prevent oxidation during casting,{{cite web|url=http://www.epa.gov/magnesium-sf6/documents/tms_paper.pdf |title=Update on EPA's manesium industry partnership for climate protection |author=Scott C. Bartos |publisher=US Environmental Protection Agency |date=February 2002 |access-date=December 14, 2013 |url-status=dead|archive-url=https://web.archive.org/web/20121010163051/http://www.epa.gov/magnesium-sf6/documents/tms_paper.pdf |archive-date=October 10, 2012 }} and other processes including smelting.{{cite news |first=John |last=Ayres |publisher=Environment Canada |url=https://www.epa.gov/sites/default/files/2016-02/documents/conf00_ayres_paper.pdf |title=Canadian Perspective on SF6 Management from Magnesium Industry |date=2000}} Once the largest user, consumption has declined greatly with capture and recycling.
• Insulated glazing windows have used it as a filler to improve their thermal and acoustic insulation performance.{{cite web |url=http://www.oekorecherche.de/sites/default/files/publikationen/ecofys_oekorecherchestudy.pdf |title=Final report on the costs and the impact on emissions of potential regulatory framework for reducing emissions of hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride |author=J. Harnisch and W. Schwarz |date=2003-02-04 |publisher=Ecofys GmbH}}{{cite book|url=https://books.google.com/books?id=bqUxCGJd0owC&q=hexafluoride+insulating+glass&pg=PA504 |title=Sound insulation - Google Books |isbn=9780750665261 |last1=Hopkins |first1=Carl |year=2007 |pages=504–506|publisher=Elsevier / Butterworth-Heinemann }}
• {{chem|SF|6}} plasma is used in the semiconductor industry as an etchant in processes such as deep reactive-ion etching. A small fraction of the {{chem|SF|6}} breaks down in the plasma into sulfur and fluorine, with the fluorine ions performing a chemical reaction with silicon.{{cite web|url=http://www.eng.auburn.edu/~tzengy/Publications/Plasma%20Lab%20Publications/Dry%20etching%20of%20silicon%20materials%20in%20SF6%20based%20plasma.pdf |title=Dry Etching of Silicon Materials in {{chem|SF|6}} Based Plasmas |date=September 1987 |author1=Y. Tzeng |author2=T.H. Lin |publisher=Journal of the Electrochemical Society |access-date=22 February 2013 |url-status=dead|archive-url=https://web.archive.org/web/20120406111056/http://www.eng.auburn.edu/~tzengy/Publications/Plasma%20Lab%20Publications/Dry%20etching%20of%20silicon%20materials%20in%20SF6%20based%20plasma.pdf |archive-date=6 April 2012 }}
• Tires filled with it take longer to deflate from diffusion through rubber due to the larger molecule size.
• Nike likewise used it to obtain a patent and to fill the cushion bags in all of their "Air"-branded shoes from 1992 to 2006.{{cite web |url= http://www.businessweek.com/stories/2006-09-24/nike-goes-for-the-green |title= Nike Goes For The Green |author= Stanley Holmes |publisher= Bloomberg Business Week Magazine |date= September 24, 2006 |access-date= December 14, 2013 |url-status= dead |archive-url= https://web.archive.org/web/20130603225645/http://www.businessweek.com/stories/2006-09-24/nike-goes-for-the-green |archive-date= June 3, 2013 }} 277 tons was used during the peak in 1997.
• The United States Navy's Mark 50 torpedo closed Rankine-cycle propulsion system is powered by sulfur hexafluoride in an exothermic reaction with solid lithium.{{cite journal|title=Stored Chemical Energy Propulsion System for Underwater Applications|author1=Hughes, T.G. |author2=Smith, R.B. |author3=Kiely, D.H. |journal= Journal of Energy|year= 1983|volume=7|issue=2 |pages=128–133|doi=10.2514/3.62644|bibcode=1983JEner...7..128H }}
• Waveguides in high-power microwave systems are pressurized with it. The gas electrically insulates the waveguide, preventing internal arcing.
• Electrostatic loudspeakers have used it because of its high dielectric strength and high molecular weight.{{cite web |url= http://www.theabsolutesound.com/articles/advances-in-loudspeaker-technology-a-50-year-perspective-tas-196/ |title= Advances in loudspeaker technology - A 50 year prospective |author= Dick Olsher |publisher= The Absolute Sound |date= October 26, 2009 |access-date= December 14, 2013 |url-status= live |archive-url= https://web.archive.org/web/20131214091113/http://www.theabsolutesound.com/articles/advances-in-loudspeaker-technology-a-50-year-perspective-tas-196/ |archive-date= December 14, 2013 }}
• Disulfur decafluoride, a chemical weapon, is produced with it as a feedstock.
• For entertainment purposes, when breathed, {{chem|SF|6}} causes the voice to become significantly deeper, due to its density being so much higher than air. This phenomenon is related to the more well-known effect of breathing low-density helium, which causes someone's voice to become much higher. Both of these effects should only be attempted with caution as these gases displace oxygen that the lungs are attempting to extract from the air. Sulfur hexafluoride is also mildly anesthetic.{{cite journal | url=http://anesthesiology.pubs.asahq.org/article.aspx?articleid=1964594|title=Anesthetic Potencies of Sulfur Hexafluoride, Carbon Tetrafluoride, Chloroform and Ethrane in Dogs: Correlation with the Hydrate and Lipid Theories of Anesthetic Action|journal=Anesthesiology: The Journal of the American Society of Anesthesiologists|volume=30|issue=2|pages=127–134|publisher=Anesthesiology - The Journal of the American Society of Anesthesiologists, Inc|date=September 10, 1968|author=Edmond I Eger MD |display-authors=etal }}{{cite AV media|author=WTOL|publisher=Imagination Station|date=2015-01-27|title=Sound Like Darth Vader with Sulfur Hexafluoride|url=https://www.youtube.com/watch?v=A7XdOyZIkko|website=YouTube}}
• For science demonstrations / magic as "invisible water" since a light foil boat can be floated in a tank, as will an air-filled balloon.
• It is used for benchmark and calibration measurements in Associative and Dissociative Electron Attachment (DEA) experiments{{cite journal|last1=Braun|first1=M|last2=Marienfeld|first2=S|last3=Ruf|first3=M-W|last4=Hotop|first4=H|date=2009-05-26|title=High-resolution electron attachment to the molecules CCl4and SF6over extended energy ranges with the (EX)LPA method|url=https://iopscience.iop.org/article/10.1088/0953-4075/42/12/125202|journal=Journal of Physics B: Atomic, Molecular and Optical Physics|language=en|volume=42|issue=12|pages=125202|doi=10.1088/0953-4075/42/12/125202|bibcode=2009JPhB...42l5202B|s2cid=122242919|issn=0953-4075}}{{cite journal|last1=Fenzlaff|first1=Marita|last2=Gerhard|first2=Rolf|last3=Illenberger|first3=Eugen|date=1988-01-01|title=Associative and dissociative electron attachment by SF6 and SF5Cl|url=https://aip.scitation.org/doi/10.1063/1.454646|journal=The Journal of Chemical Physics|volume=88|issue=1|pages=149–155|doi=10.1063/1.454646|bibcode=1988JChPh..88..149F|issn=0021-9606}}

File:SF6 mm.png|Sulfur hexafluoride (SF₆) measured by the Advanced Global Atmospheric Gases Experiment ([http://agage.mit.edu/ AGAGE]) in the lower atmosphere (troposphere) at stations around the world. Abundances are given as pollution free monthly mean mole fractions in parts-per-trillion.

File:AGAGE sulfur hexafluroride growth.png|Abundance and growth rate of {{chem|SF|6}} in Earth's troposphere (1978-2018).Simmonds, P. G., Rigby, M., Manning, A. J., Park, S., Stanley, K. M., McCulloch, A., Henne, S., Graziosi, F., Maione, M., and 19 others (2020) "The increasing atmospheric burden of the greenhouse gas sulfur hexafluoride (SF₆)". Atmos. Chem. Phys., 20: 7271–7290. {{doi|10.5194/acp-20-7271-2020}}. 50px Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].

File:Halogenated gas concentrations 1978-present.png|Atmospheric concentration of SF₆ vs. similar man-made gases (right graph). Note the log scale.

According to the Intergovernmental Panel on Climate Change, {{chem|SF|6}} is the most potent greenhouse gas. Its global warming potential of 23,900 times that of carbon dioxide when compared over a 100-year period.{{cite web |url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-10-2.html |title=2.10.2 Direct Global Warming Potentials |year=2007 |publisher=Intergovernmental Panel on Climate Change |access-date=22 February 2013 |url-status=live |archive-url=https://web.archive.org/web/20130302061433/http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-10-2.html |archive-date=2 March 2013 }} Sulfur hexafluoride is inert in the troposphere and stratosphere and is extremely long-lived, with an estimated atmospheric lifetime of 800–3,200 years.{{cite journal |author=A. R. Ravishankara, S. Solomon, A. A. Turnipseed, R. F. Warren |date=8 January 1993 |title=Atmospheric Lifetimes of Long-Lived Halogenated Species |journal=Science |volume=259 |issue=5092 |pages=194–199 |url=https://www.science.org/doi/abs/10.1126/science.259.5092.194 |access-date=22 February 2013 |bibcode=1993Sci...259..194R |last2=Solomon |last3=Turnipseed |last4=Warren |doi=10.1126/science.259.5092.194 |pmid=17790983 |s2cid=574937 |url-status=live |archive-url=https://web.archive.org/web/20150924144127/http://www.sciencemag.org/content/259/5092/194.abstract |archive-date=24 September 2015 }}

Measurements of SF₆ show that its global average mixing ratio has increased from a steady base of about 54 parts per quadrillion prior to industrialization, to over 11.5 parts per trillion (ppt) as of October 2023, and is increasing by about 0.4 ppt (3.5%) per year.{{cite web |url=https://www.esrl.noaa.gov/gmd/ccgg/trends_sf6/ |title=Trends in Atmospheric Sulpher Hexaflouride |publisher=US National Oceanic and Atmospheric Administration |access-date=28 December 2023}}{{cite web|url=ftp://aftp.cmdl.noaa.gov/data/hats/sf6/insituGCs/CATS/monthly/smo_SF6_MM.dat |title=Sulfur hexafluoride (SF₆) data from hourly in situ samples analyzed on a gas chromatograph located at Cape Matatulu (SMO)|date=July 7, 2020|access-date=August 8, 2020}} Average global SF₆ concentrations increased by about 7% per year during the 1980s and 1990s, mostly as the result of its use in magnesium production, and by electrical utilities and electronics manufacturers. Given the small amounts of SF₆ released compared to carbon dioxide, its overall individual contribution to global warming is estimated to be less than 0.2%,{{cite web |url=http://powerplantccs.com/blog/2011/03/sf6-sulfur-hexafluoride.html |title=SF₆ Sulfur Hexafluoride |date=19 March 2011 |publisher=PowerPlantCCS Blog |access-date=22 February 2013 |url-status=live |archive-url=https://web.archive.org/web/20121230202321/http://powerplantccs.com/blog/2011/03/sf6-sulfur-hexafluoride.html |archive-date=30 December 2012 }} however the collective contribution of it and similar man-made halogenated gases has reached about 10% as of 2020.{{cite web |url=https://www.esrl.noaa.gov/gmd/aggi/aggi.html |title=The NOAA Annual Greenhouse Gas Index (AGGI) |publisher=NOAA Global Monitoring Laboratory/Earth System Research Laboratories |author=Butler J. and Montzka S. |year=2020 }} Alternatives are being tested.{{cite web |title=g3, the SF6-free solution in practice {{!}} Think Grid |url=https://think-grid.org/g3-sf6-free-solution-practice |website=think-grid.org |date=18 February 2019 |access-date=6 February 2020 |archive-date=30 October 2020 |archive-url=https://web.archive.org/web/20201030203625/https://think-grid.org/g3-sf6-free-solution-practice |url-status=dead }}{{cite journal |author1=Mohamed Rabie |author2=Christian M. Franck |title=Assessment of Eco-friendly Gases for Electrical Insulation to Replace the Most Potent Industrial Greenhouse Gas SF6 |journal=Environmental Science & Technology |year=2018 |volume=52 |issue=2 |pages=369–380 |publisher=American Chemical Society |doi=10.1021/acs.est.7b03465|pmid=29236468 |bibcode=2018EnST...52..369R |hdl=20.500.11850/238519 |hdl-access=free }}

In Europe, {{chem|SF|6}} falls under the F-Gas directive which ban or control its use for several applications.{{cite web |url=https://phys.org/news/2020-01-sulfur-hexafluoride-truths-myths-greenhouse.html |title=Sulfur hexafluoride: The truths and myths of this greenhouse gas |author=David Nikel |publisher=phys.org |date=2020-01-15 |access-date=2020-10-18}} Since 1 January 2006, {{chem|SF|6}} is banned as a tracer gas and in all applications except high-voltage switchgear.{{cite news |url=http://www.euractiv.com/sustainability/climate-meps-give-gas-bill-green-boost/article-145749 |title=Climate: MEPs give F-gas bill a 'green boost' |newspaper=www.euractiv.com |date=13 October 2005 |publisher=EurActiv.com |access-date=22 February 2013 |url-status=live |archive-url= https://web.archive.org/web/20130603001718/http://www.euractiv.com/sustainability/climate-meps-give-gas-bill-green-boost/article-145749 |archive-date=3 June 2013 }} It was reported in 2013 that a three-year effort by the United States Department of Energy to identify and fix leaks at its laboratories in the United States such as the Princeton Plasma Physics Laboratory, where the gas is used as a high voltage insulator, had been productive, cutting annual leaks by {{convert|2280|lb|kg|order=flip|abbr=off}}. This was done by comparing purchases with inventory, assuming the difference was leaked, then locating and fixing the leaks.{{cite news|title=Department of Energy's Crusade Against Leaks of a Potent Greenhouse Gas Yields Results|url=https://www.nytimes.com/2013/06/14/us/department-of-energys-crusade-against-leaks-of-a-potent-greenhouse-gas-yields-results.html |access-date=June 14, 2013|newspaper=The New York Times|date=June 13, 2013|author=Michael Wines|url-status=live|archive-url= https://web.archive.org/web/20130614114649/http://www.nytimes.com/2013/06/14/us/department-of-energys-crusade-against-leaks-of-a-potent-greenhouse-gas-yields-results.html |archive-date=June 14, 2013|author-link=Michael Wines}}

Sulfur hexafluoride is a nontoxic gas, but by displacing oxygen in the lungs, it also carries the risk of asphyxia if too much is inhaled.{{cite web|title=Sulfur Hexafluoride|url=http://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+825|work=Hazardous Substances Data Bank|publisher=U.S. National Library of Medicine|access-date=26 March 2013|url-status=live|archive-url=https://web.archive.org/web/20180509021853/https://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+825|archive-date=9 May 2018}} Since it is more dense than air, a substantial quantity of gas, when released, will settle in low-lying areas and present a significant risk of asphyxiation if the area is entered. That is particularly relevant to its use as an insulator in electrical equipment since workers may be in trenches or pits below equipment containing {{chem|SF|6}}.{{cite web|title=Guide to the safe use of SF₆ in gas|url=http://www.eurelectric.org/Download/Download.aspx?DocumentID=2136|publisher=UNIPEDE/EURELECTRIC|access-date=2013-09-30|url-status=live|archive-url=https://web.archive.org/web/20131004224624/http://www.eurelectric.org/Download/Download.aspx?DocumentID=2136|archive-date=2013-10-04}}

File:Sulfur Hexafluoride (SF6) Surprise.webm

As with all gases, the density of {{chem|SF|6}} affects the resonance frequencies of the vocal tract, thus changing drastically the vocal sound qualities, or timbre, of those who inhale it. It does not affect the vibrations of the vocal folds. The density of sulfur hexafluoride is relatively high at room temperature and pressure due to the gas's large molar mass. Unlike helium, which has a molar mass of about 4 g/mol and pitches the voice up, {{chem|SF|6}} has a molar mass of about 146 g/mol, and the speed of sound through the gas is about 134 m/s at room temperature, pitching the voice down. For comparison, the molar mass of air, which is about 80% nitrogen and 20% oxygen, is approximately 30 g/mol which leads to a speed of sound of 343 m/s.{{cite web |url=http://www.animations.physics.unsw.edu.au/jw/speech.html |title=Physics in Speech |publisher=University of New South Wales |access-date=22 February 2013 |url-status=live |archive-url=https://web.archive.org/web/20130221043110/http://www.animations.physics.unsw.edu.au/jw/speech.html |archive-date=21 February 2013 }}

Sulfur hexafluoride has an anesthetic potency slightly lower than nitrous oxide;{{cite book | isbn = 9780398000110 | title = The Chemistry and Physics of Anesthesia |edition=2nd | last1 = Adriani | first1 = John | year = 1962 | publisher = Thomas Books | location = Illinois | page = 319 }} it is classified as a mild anesthetic.{{cite journal |last1=Weaver |first1=Raymond H. |last2=Virtue |first2=Robert W. |title=The mild anesthetic properties of sulfur hexafluoride |url=https://anesthesiology.pubs.asahq.org/article.aspx?articleid=1971324 |journal=Anesthesiology |pages=605–607 |language=en |date=1 November 1952|volume=13 |issue=6 |doi=10.1097/00000542-195211000-00006 |pmid=12986223 |s2cid=32403288 |doi-access=free }}

• Selenium hexafluoride
• Tellurium hexafluoride
• Uranium hexafluoride
• Hypervalent molecule
• Halocarbon—another group of major greenhouse gases
• Trifluoromethylsulfur pentafluoride, a similar gas

{{reflist|30em}}

• {{cite web |url=http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=34 |title=Sulfur hexafluoride |publisher=Air Liquide Gas Encyclopedia |access-date=22 February 2013 |url-status=live |archive-url=https://web.archive.org/web/20120331215233/http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=34 |archive-date=31 March 2012 }}
• {{cite book |editor = Christophorou, Loucas G. |editor2=Isidor Sauers |editor2-link=Isidor Sauers | year = 1991 | title = Gaseous Dielectrics VI | publisher = Plenum Press | isbn = 978-0-306-43894-3 }}
• {{cite book|last1=Holleman |first1=A. F. |last2=Wiberg |first2=E. |title=Inorganic Chemistry |publisher=Academic Press |location=San Diego |date=2001 |isbn=0-12-352651-5}}
• {{cite book |title=High-Voltage Engineering: Theory and Practice |last1=Khalifa |first1=Mohammad |year=1990 |publisher=Marcel Dekker |location=New York |isbn=978-0-8247-8128-6 |oclc=20595838}}
• {{cite book |title=Advantages in High Voltage Insulation and Arc Interruption in SF₆ and Vacuum |last1=Maller |first1=V. N. |last2=Naidu |first2=M. S. |year=1981 |publisher=Pergamon Press |location=Oxford; New York |isbn=978-0-08-024726-7 |oclc=7866855}}
• [https://web.archive.org/web/20061003003615/http://www.epa.gov/electricpower-sf6/ SF₆ Reduction Partnership for Electric Power Systems]
• {{cite web | url=https://www.bbc.com/news/science-environment-49567197 | title=Climate change: Electrical industry's 'dirty secret' boosts warming | work=BBC News | date=September 13, 2019 | access-date=September 14, 2019 | author=Matt McGrath}}

{{Wiktionary|fluoroketone}}

• [https://web.archive.org/web/20060116134617/http://www.npi.gov.au/database/substance-info/profiles/44.html Fluoride and compounds fact sheet]— National Pollutant Inventory
• [https://web.archive.org/web/20121018211612/http://www.epa.gov/highgwp/scientific.html High GWP Gases and Climate Change] from the U.S. EPA website
• [https://web.archive.org/web/20061007210032/http://www.epa.gov/highgwp/magnesium-sf6/workshops.html International Conference on SF₆ and the Environment] ([https://web.archive.org/web/20090426064312/http://www.epa.gov/highgwp/electricpower-sf6/basic.html related archive])
• [https://www.cdc.gov/niosh/npg/npgd0576.html CDC - NIOSH Pocket Guide to Chemical Hazards]

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Category:Sulfur fluorides

Category:Dielectric gases

Category:Greenhouse gases

Category:Octahedral compounds

Category:Hexafluorides

Category:Industrial gases

Category:Refrigerants

Category:Hypervalent molecules

Category:General anesthetics

Category:Ultrasound contrast agents