Sulfur hexafluoride (SF6) is an inorganic, colorless, odorless, and non-flammable greenhouse gas. SF6 has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom. It is a hypervalent molecule. Typical for a nonpolar gas, it is poorly soluble in water but soluble in nonpolar organic solvents. It is generally transported as a liquefied compressed gas. It has a density of 6.12 g/L at sea level conditions, which is considerably higher than the density of air (1.225 g/L).SF6 is used in the electrical industry as a gaseous dielectric medium for high-voltage circuit breakers, switchgear, and other electrical equipment, often replacing oil filled circuit breakers (OCBs) that can contain harmful PCBs. SF6 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.SF6 is used to provide a tamponade or plug of a retinal hole in retinal detachment repair operations in the form of a gas bubble. It is inert in the vitreous chamber and initially doubles its volume in 36 hours before being absorbed in the blood in 10-14 days.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.SF6 plasma is also used in the semiconductor industry as an etchant. SF6 breaks down in the plasma into sulfur and fluorine, the fluorine plasma performing the etching.
The magnesium industry uses large amounts of SF6 as inert gas to fill casting forms.
Sulfur hexafluoride is also used to pressurize waveguides in radar systems. The gas insulates the waveguide preventing internal arcing. The same use of sulfur hexafluoride is applied in transmission waveguides of medical linear accelerators, which are used for delivery of external beam radiotherapy.
Sulfur hexafluoride has been used in electrostatic loudspeakers because of its high dielectric strength and high molecular weight.
Sulfur hexafluoride has been used to fill tyres of racing cars in professional events due to its non-flammability and high density.
