Phenomena

Inside a Can of Compressed Air

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Many gases are stored in liquid form at high pressures. This video takes a look at tetrafluoroethane, better known as the substance in compressed air cans used for dusting electronics. At atmospheric pressure, tetrafluoroethane boils at about -26 degrees Celsius, but in an air duster, at around 7 atmospheres of pressure, it is a liquid. As demonstrated in the video, releasing the pressure causes the liquid to boil off. Even exposed to atmospheric pressure, though, the liquid doesn’t boil off instantly – the act of boiling requires thermal energy and, without a sufficient source of heat, the liquid consumes its own heat until it drops to a temperature below the boiling point. As it warms up from the surrounding air, it will start boiling again. I don’t recommend trying to open up an air duster can at home, though. High-pressure containers can be dangerous to open up, and tetrafluoroethane is now being phased out in some parts of the world due to its high global warming potential.  (Video credit: N. Moore)

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