Air question

[susandennis]

When you buy canned air and then you use up all the air, it still blows.  You don't get that wet cold stuff but you get air coming out which is, honestly, all I feel I can ask out of a can of air. So, why would you ever need a new one?  What's the magic to that wet cold stuff? 

How redundant would it be to mention that I dropped out of chemistry when half of my 23 unknowns evaporated before I could get to them?  And I just flat failed physics.  Somehow I think one or both of those disciplines would have helped me understand why my empty can of air is still giving me a decent blow job and why I should not think it's decent and should go buy a new one.

Seriously.  Really.

Comments

[vasilatos]

Yowza, that sounds like a good deal. I don't like the wet cold stuff, would be very happy with just air. This news bodes well for my future. Thanks!

[susandennis]

Nothing new. Buy a can of air and just hold down that little lever until it's all gone. Then you'll just get air. See, I can't even explain it! Confusionitis.

[beaq.livejournal.com]

I'm not sure what you mean by "it still blows". Wouldn't that mean it's not empty?

[susandennis]

I know I don't know how to explain it. (And I'm really distracted by your hilarious user pic!)

When you get a new can of air and you push that little trigger thing, it blasts out cold, wet something. Oh and when you shake the can you can feel that it is full of liquid of some kind.

Then when it runs out, the air is no longer cold and wet but just blowy. And when you shake the can the liquid is gone. (That's how I know it's empty.)

[beaq.livejournal.com]

Unedumacated guess: the liquid in the can is what turns into the "air" that comes out. When most of it is gone, it stops being liquid but there is still some in there. (It stops being cold because of the, er, thingy with compressed gases sucking up energy as they evaporate -- I think it's only cold while you're spraying, rahter than while it sits there.)

Keep spraying -- I bet it isn't infinite.

[beaq.livejournal.com]

Oh!

http://en.wikipedia.org/wiki/Canned_air

That doesn't explain, exactly, but yields some clues.

[rsc.livejournal.com]

Close enough. As I suspected from what had been said so far (I'd never heard of the stuff), "canned air" isn't air. But of course when you spray the contents out, air flows in -- that's at least part of how the spray mechanism works, and if it didn't you'd end up with a can of vacuum which, unless it was made of stronger material than most such cans are, would collapse under the pressure of the air outside it.

Now when you spary it, air flows out, and other air flows in to replace it.

[susandennis]

Seriouisly? You've never heard of it? I use it constantly - blow out my keyboard, blow out Roomba, blow out the backs of the TiVos and the cable box and my computer. And, now, thanks to Wikipedia, I know I could use it to get high if I were a teenager.

[roadskoller.livejournal.com]

I just asked my husband, who happens to know some of these things, and he hasn't a clue. I love that about him.

[susandennis]

And you know what?! I love that about him, too! And thanks so much for asking. I'm beginning to think maybe this isnt' a dumb question!

[roadskoller.livejournal.com]

I can't wait until we find someone who knows. I'll keep watching.

[pheon.livejournal.com]

Eventually after the cold goes away, the ooomph (that's a technical term; don't let it throw you) will also depart. [Seriously, the cold stuff is something --- usually one of the ethanes --- that is a liquid when compressed, but rapidly turns to a gas at room temperature/pressure.]

It's closely related to the fact that electronic devices run on smoke. Once the smoke leaks out, they don't work anymore.

[susandennis]

ooomph! that's the word I needed... I just wrote the date on my can that's out of ethane and the one that's still full. We'll be tracking these...

[cpratt.livejournal.com]

This is a perfect question to send to New Scientist magazine - the last page in every issue tackles questions like this, all sent in by readers.

[susandennis]

Done. I just found their website and a link to send a 'final word' question and I did! Thanks!

[susandennis]

And just now I got an ack and learned they will pay me 25 pounds if my question is used! I can buy lots of air with that!

And, by the way, the editor, Lucy, is out until after Xmas. I got her oof!

[jimcarson.livejournal.com]

OOoh, I wonder if British air has a more distinctive ... air ... to it?

[susandennis]

I love it when you take the low road.