How does an oxygen canister on an airplane work?

When you think of storing oxygen, metal tanks full of gas might come to mind. There's also a chemical method -- tune in to this podcast from HowStuffWorks.com to learn about how oxygen canisters work.

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Episode Transcript

Speaker 1 (00:00):
Welcome to brain Stuff from how stuff Works dot com.
We're smart Happens. Hi. I'm Marshall Brain with today's question,
how does an oxygen canister on an airplane work? When
we think of store to oxygen, we usually think about

(00:22):
a large metal tank holding pressurized oxygen gas. This is
the way we see oxygen in hospitals and on welding rigs.
We also see scuba divers taking their oxygen with them
in the form of compressed air and scuba tanks. Because
these tanks are so common, we tend to think that
they are the only way to store oxygen. It turns
out that there's also a chemical way to store oxygen.

(00:45):
Many chemicals, including potassium chlorate and sodium chlorate, are rich
in oxygen, and they're willing to give it up as
a nearly pure gas when they get heated. The scuba
tanks that divers wear might weigh up to eighty pounds
but can only store an hour or two of air.
An oxygen canister weighing half that can provide about four

(01:07):
days worth of oxygen. The sodium chlorate is acting something
like an oxygen sponge, and you squeeze the oxygen out
of that sponge with heat. Modern oxygen canisters are extremely
lightweight and they store a lot of oxygen. You find
oxygen canisters, also known as chemical oxygen generators, on airplanes, submarines,

(01:28):
and space stations, places where oxygen can run out unexpectedly. Typically,
an oxygen canister contains a sodium chlorate pellet and an igniter.
The igniter can be triggered by friction or impact. It
generates enough heat to start the sodium chlorate reaction, and
then the heat of the reaction sustains itself. The sodium

(01:49):
chlorate does not burn, its decomposition, just happens to give
off lots of heat and lots of oxygen. The reason
why oxygen canisters can cause fire is because they're hot
and they generate oxygen. Anything nearby that happens to ignite
will burn incredibly intensely because of that rich oxygen supply.

(02:12):
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