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Sulphur hexafluoride (SF6)

Hazard Knowledge

Sulphur hexafluoride gas is used at low pressures to insulate certain areas of power stations and substations, and for arc extinction in switchgear. Sulphur hexafluoride gas in its pure form is inert, colourless, non-flammable, non-toxic and five times heavier than air.

In substations it is sealed in compartments that should have a warning sign denoting SF6 presence. It can only escape in fault conditions, which include fires, when it can generate toxic and corrosive gases or powder that can cause skin burns and severe damage to eyes.