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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. [29] The gas was released throughout the station, and monitored as it drifted around.
Sulfur hexafluoride circuit breakers protect electrical power stations and distribution systems by interrupting electric currents, when tripped by a protective relay. Instead of oil, air, or a vacuum, a sulfur hexafluoride circuit breaker uses sulfur hexafluoride (SF 6 ) gas to cool and quench the arc on opening a circuit.
Moisture analysis is used for early detection of this. Dielectric gases can also serve as coolants. Vacuum is an alternative for gas in some applications. Mixtures of gases can be used where appropriate. Addition of sulfur hexafluoride can dramatically improve the dielectric properties of poorer insulators, e.g. helium or nitrogen. [2]
Sulphur hexafluoride (SF 6) is used primarily as an arc suppression and insulation gas. It can be found in high-voltage switchgear and is used in the production of magnesium. Nitrogen trifluoride (NF 3) is used primarily as an etchant for microelectronics fabrication.
Sulfur hexafluoride is nearly inert and non-toxic due to steric hindrance (the six fluorine atoms are arranged so tightly around the sulfur atom that it is extremely difficult to attack the bonds between the fluorine and sulfur atoms). It has several applications due to its stability, dielectric properties, and high density.
Sulfur hexafluoride can be added to shield gas for aluminium welding to bind hydrogen in the weld area to reduce weld porosity. [11] Dichlorodifluoromethane with argon can be used for protective atmosphere for melting of aluminium-lithium alloys. [12] It reduces the content of hydrogen in the aluminium weld, preventing the associated porosity.
Sulfur hexafluoride is also used in soundproof windows, in the electronics industry, as well as niche medical and military applications. The compound can be made without using fluorine gas, but the reaction between sulfur and fluorine gas, first developed by Henri Moissan, remains the commercial practice.
Sulfur hexafluoride is used for cooling and insulating of some high-voltage power systems (circuit breakers, switches, some transformers, etc.). Steam can be used where high specific heat capacity is required in gaseous form and the corrosive properties of hot water are accounted for.