Sulphur HexaFluoride gas

Sulphur Hexafluoride is a gas that finds widespread use in Electric Switchgear.  

Its introduction over forty years ago led to a revolution in the design of electric switchgear.  Its excellent dielectric and arc-quenching properties led to drastic reduction in the size of electric switchgear. 

It is non-toxic, chemically inert and high thermal stability.  These characteristics have made it an ideal gas for use in switchgear to quench arcs which may for when circuit breakers operate.  Sulphur hexafluoride is also used in Gas insulated switchgear (Switchgear which are constructed inside a cylinder containing SF6 gas).  These switchgear are compact and occupy very less space.

Sulphur Hexafluoride is not a naturally occurring gas.  It is synthesized by the exposure of Sulphur and Fluorine.  Unfortunately, the SF6 gas is a greenhouse gas an thus should never be directly released into the atmosphere.  Hence, alternatives to SF6 gas are being explored.

When circuit breakers operate and current is interrupted, arcing occurs.  This arcing can cause the sulphur hexafluoride to decompose.  The products thus formed can be corrosive. Most of the products of decomposition recombine to form sulphur hexafluoride.  However, one of the products, Disulphur decafluoride is highly toxic.  Protective equipment for breathing and eye protection should be used when working in proximity to sulphur hexa fluoride gas.