# Although the bag will not inflate, there is oxygen flowing to the mask.

**URL:** <https://boards.straightdope.com/t/although-the-bag-will-not-inflate-there-is-oxygen-flowing-to-the-mask/242260>\
**Category:** Factual Questions\
**Created:** [April 27, 2004, 11:21am UTC](https://boards.straightdope.com/t/although-the-bag-will-not-inflate-there-is-oxygen-flowing-to-the-mask/242260 "2004-04-27T11:21:01Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![bienville](https://avatars.discourse-cdn.com/v4/letter/b/4bbf92/32.png) [@bienville](https://boards.straightdope.com/u/bienville)\
**Post date:** [April 27, 2004, 11:21am UTC](https://boards.straightdope.com/t/although-the-bag-will-not-inflate-there-is-oxygen-flowing-to-the-mask/242260/1 "2004-04-27T11:21:01Z")

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On an airplane the emergency oxygen masks go like this: Tube - Bag - Mask.

Now we’ve all been told that the bag does not inflate. We’re told this everytime we fly. Now I assume the reason they make such a point of always mentioning this must have to do with the assumption that people will expect that the bag _should_ inflate and (already in a frightening emergency situation) people may become very worried when they see that their bag is not inflating.

So, if the bag is not supposed to inflate, why is there a bag at all?

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**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\
**Post date:** [April 27, 2004, 11:39am UTC](https://boards.straightdope.com/t/although-the-bag-will-not-inflate-there-is-oxygen-flowing-to-the-mask/242260/2 "2004-04-27T11:39:13Z")

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My guess – to provide a reserve area where air _can_ go, if necessary, yet keep the system sealed.

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**Author:** ![Peter\_Doubt](https://avatars.discourse-cdn.com/v4/letter/p/df705f/32.png) [@Peter\_Doubt](https://boards.straightdope.com/u/Peter_Doubt)\
**Post date:** [April 27, 2004, 11:47am UTC](https://boards.straightdope.com/t/although-the-bag-will-not-inflate-there-is-oxygen-flowing-to-the-mask/242260/3 "2004-04-27T11:47:28Z")

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That type of O2 mask is termed a non rebreather with reservoir bag. It has a one way valve, made that way so you don’t rebreath as much CO2 if you were literally gasping for air.

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**Author:** ![bienville](https://avatars.discourse-cdn.com/v4/letter/b/4bbf92/32.png) [@bienville](https://boards.straightdope.com/u/bienville)\
**Post date:** [April 27, 2004, 12:00pm UTC](https://boards.straightdope.com/t/although-the-bag-will-not-inflate-there-is-oxygen-flowing-to-the-mask/242260/4 "2004-04-27T12:00:51Z")

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> [@Sender](#):
>
> It has a one way valve, made that way so you don’t rebreath as much CO2 if you were literally gasping for air.

**Sender** , I know all the words in this sentence but I can’t seem to grasp the meaning. Can you elaborate a bit to help a dummy?

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**Author:** ![glilly](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@glilly](https://boards.straightdope.com/u/glilly)\
**Post date:** [April 27, 2004, 1:37pm UTC](https://boards.straightdope.com/t/although-the-bag-will-not-inflate-there-is-oxygen-flowing-to-the-mask/242260/5 "2004-04-27T13:37:02Z")

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[Cecil](http://www.straightdope.com/classics/a3_140.html)

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**Author:** ![smoke](https://avatars.discourse-cdn.com/v4/letter/s/c5a1d2/32.png) [@smoke](https://boards.straightdope.com/u/smoke)\
**Post date:** [April 27, 2004, 2:52pm UTC](https://boards.straightdope.com/t/although-the-bag-will-not-inflate-there-is-oxygen-flowing-to-the-mask/242260/6 "2004-04-27T14:52:47Z")

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So, what is this incident that Cecil spoke of? Not that I disbelieve him, but I’m wondering when and where it happened that people took their masks off when they saw the bags weren’t inflating. Did anyone die?