Sulfur hexafluoride is a colorless, odorless, nontoxic, nonflammable gas that has a high dielectric strength and serves widely as an insulating gas in electrical equipment.
At atmospheric pressures it sublimes directly from the solid to the gas phase and does not have a stable liquid phase unless under a pressure of more than 32 psia (221 kPa abs).
Sulfur hexafluoride is employed extensively as a gaseous dielectric in various kinds of electrical power equipment, such as switchgear, transformers, condensers, and circuit breakers. It has also been used as a dielectric at microwave frequencies and as an insulating medium for the power supplies of high-voltage machines.
Sulfur fluoride is also gaining use in nonelectrical applications, including blanketing molten magnesium, leak detection, and plasma etching in the semiconductor industry. Sulfur hexafluoride also has some limited medical applications.