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Speaker 1: Welcome to brain Stuff from how stuff Works dot com.

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Speaker 1: We're smart Happens. Hi. I'm Marshall Brain with today's question,

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Speaker 1: how does an oxygen canister on an airplane work? When

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Speaker 1: we think of store to oxygen, we usually think about

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Speaker 1: a large metal tank holding pressurized oxygen gas. This is

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Speaker 1: the way we see oxygen in hospitals and on welding rigs.

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Speaker 1: We also see scuba divers taking their oxygen with them

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Speaker 1: in the form of compressed air and scuba tanks. Because

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Speaker 1: these tanks are so common, we tend to think that

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Speaker 1: they are the only way to store oxygen. It turns

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Speaker 1: out that there's also a chemical way to store oxygen.

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Speaker 1: Many chemicals, including potassium chlorate and sodium chlorate, are rich

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Speaker 1: in oxygen, and they're willing to give it up as

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Speaker 1: a nearly pure gas when they get heated. The scuba

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Speaker 1: tanks that divers wear might weigh up to eighty pounds

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Speaker 1: but can only store an hour or two of air.

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Speaker 1: An oxygen canister weighing half that can provide about four

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Speaker 1: days worth of oxygen. The sodium chlorate is acting something

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Speaker 1: like an oxygen sponge, and you squeeze the oxygen out

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Speaker 1: of that sponge with heat. Modern oxygen canisters are extremely

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Speaker 1: lightweight and they store a lot of oxygen. You find

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Speaker 1: oxygen canisters, also known as chemical oxygen generators, on airplanes, submarines,

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Speaker 1: and space stations, places where oxygen can run out unexpectedly. Typically,

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Speaker 1: an oxygen canister contains a sodium chlorate pellet and an igniter.

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Speaker 1: The igniter can be triggered by friction or impact. It

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Speaker 1: generates enough heat to start the sodium chlorate reaction, and

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Speaker 1: then the heat of the reaction sustains itself. The sodium

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Speaker 1: chlorate does not burn, its decomposition, just happens to give

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Speaker 1: off lots of heat and lots of oxygen. The reason

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Speaker 1: why oxygen canisters can cause fire is because they're hot

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Speaker 1: and they generate oxygen. Anything nearby that happens to ignite

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Speaker 1: will burn incredibly intensely because of that rich oxygen supply.

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