BrainStuff Classics: Why Shouldn't Compressed Air Canisters Be Shaken?

Many spray canisters call for being shaken, but not compressed air. Learn how both types work (and the dangers of shaking the wrong type) in this classic episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff production of I Heart Radio. Hey
brain Stuff, I'm Lauren boge Bomb, and today's episode is
another classic from our archives. This one is a bit
of practical everyday science. Lots of spray canisters carry instructions
to shake before use, but not compressed air canisters, and
it's actually dangerous to do. So I'll let former Lauren

(00:24):
explain why. Hi brain Stuff, Lauren bulge Bomb here. Whether
it's dry shampoo or paint, or accustomed to shaking aerosol
canisters before we spray them, so it's only natural that
when we pick up a canister of compressed air to
clean a keyboard, we also want to shake the can
even if it's label clearly says do not shake. But

(00:45):
is this force of habit potentially harmful? In a word, yeah,
Compressed air canisters are not really canned air. Rather, these
canisters contain a compressed liquefied gas that propels its own
vapors through a nozzle. Most of the time, the liquefied
gas is one of two types. One is di fluoro
ethane or HFC one two A, which is found in

(01:07):
canisters marketed for computers and electronic equipment, and incidentally, is
also known as free on, that same gas that helps
make refrigerators and car air conditioners cool. The other type
of gas is tetrafluoro ethane or HFC one thirty four A,
which is recommended for use when flammability might be an issue,
such as with hot surfaces or spark producing equipment. However,

(01:29):
some types of can there may also contain butane, the
same liquefied gas found in cigarette lighters. According to three M,
which manufactures and cells compressed air canisters for dust removal,
shaking or tilting the can may result in propelled liquid
instead of vapor. If this happens, the liquid may come
into contact with skinner eyes and cause frost bite because
the chemical will freeze your skin at room temperature. If

(01:52):
this happens, medical attention may be warranted. But first three
M recommends washing affected areas of skinless soap and water,
or flushing eyes with copious amounts of water. But what
about all those other airsol canisters that do recommend shaking
before use. Unlike the liquefied gas and canned air that
propels itself out through the nozzle, everything from dry shampoo

(02:12):
to spray paint requires a little mixing, the product inside
the can separates into layers and must be shaken to
mix with the propellant before use, otherwise only the propellant
would come out. Today's episode is based on the article
why compressed air canisters shouldn't be shaken on how stuff

(02:33):
works dot com, written by laure L da. Brain Stuff
is production of I Heart Radio in partnership with how
stuff works dot Com, and it's produced by Tyler Clang.
Or more podcasts from my heart Radio, visit the iHeart
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