text: why do cans of compressed air get cold when you spray them?   this is agreat question.  canned air, also called duster or dust off, is a product consisting of liquified difluoroethane, trifluoroethane, or tetrafluoroethane in a spray can, with a very long nozzle that enables the user to direct a precisely focused blast of air. contrary to popular belief, the cans do not contain compressed air, as inert gases such as tetrafluoroethane are much easier to compress into liquid. hydrocarbons, like butane, were often used in the past, but their flammability forced manufacturers to use fluorocarbons.  canned air is usually used to clean or dust delicate or sensitive things such as electronics and computer equipment, as jets of gas are often gentler and sometimes more effective than other cleaning methods. using gas in spray can form is more convenient than using an air compressor or air tank.  normally, the liquid in the can immediately changes state into gas when it leaves the nozzle. gases compressed into liquids absorb much energy upon vaporization, which is why under normal use, the can becomes quite cold to the touch. turning the can upside-down and spraying does not allow for the liquid to immediately vaporize, and therefore turns the can into a freeze spray.  canned air is one of many inhalants that can be abused.