How Do Aerosol Cans Work?
If you’ve ever read the back of an aerosol can, you’ll have noticed messages such as “pressurized container” and “contents stored under pressure”. What’s that all about? To ensure that something like paint comes out evenly when you press the button on the top of an aerosol can, the manufacturers have to squeeze the contents inside with a pump or compressor (a bit like inflating a bicycle tire). Typically, the contents of an aerosol are stored at 2-8 times normal atmospheric pressure. That’s why aerosols really rush out when you press their buttons. It’s also why aerosols feel really cold when you spray them on your body. If you let a gas escape from 8 times its normal pressure into the air, it expands enormously and cools down drastically. (Gases cool when you let them expand because the heat energy their atoms or molecules contain is spread over a much bigger volume.) Photo: Many aerosols contain flammable propellants. Always read and follow the warnings on the back of the can. Don’t
