Sulfur hexafluoride (SF6)
What is SF6?
It’s an inert, colorless, odorless and non-flammable gas. Sulfur hexafuoride is about 5 times denser than air, meaning it’s heavier. If you were to fill a fish tank with SF6, you could treat the gas as if you were pouring water into a fish tank. It will collectively stay within the fish tank. It is the exact opposite of a common gas that we fill balloons with to make them float; helium.
What is SF6 used for?
SF6 is used in the electrical industry as a dielectric medium; meaning, it will insulate energized electrical parts, from de-energized or grounded parts. You can find this gaseous dielectric medium in electrical switchgear, circuit breakers or switches to name a few. SF6 is also used in the medical field, oceanographic field, and various uses in laboratories.
Why are we using it in the electrical industry?
Equipment manufacturers are able to produce higher voltage equipment with less clearances than air insulated, or oil insulated equipment. When comparing an oil filled breaker and an SF6 breaker to each other, it will be noticed that the SF6 breakers are smaller. The SF6 equipment also weighs less than the oil filled equipment. SF6 equipment does NOT contain Polychlorinated Biphenyls (PCB’s).
During electrical arc quenching from operating an SF6 breaker or switch, SF6 partially decomposes, separating into its atomic components. During this time oxygen, moisture and decomposition products such as sulphur dioxide may be created. Unlike other insulating mediums, SF6 gas has the unique ability to ‘self-heal’ with the atoms recombining after the discharge. This is another one of the reasons for its widespread use within the electrical industry.
An alternate use of SF6…
For entertainment purposes, when inhaled, SF6 causes the voice to become significantly deeper as seen in this video below. This is related to the more well-known effect of breathing low-density helium, which causes someone’s voice to become much higher. Both of these effects should only be attempted with caution as these gases displace oxygen that the lungs are attempting to extract from the air. Too much inhalation will cause asphyxiation. Sulfur hexafluoride is also mildly anesthetic. **Lastly** DO NOT INHALE SF6 DIRECTLY FROM ANY EQUIPMENT. YOU DO NOT WANT TO INHALE ANY BI-PRODUCT OF THE DECOMPOSITION OF SF6. IT CAN BE FATAL.