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#1
Old 10-18-2003, 03:12 AM
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Canned air - what is it? Why does it kill ants?

I was using some canned air on a computer today and discovered something odd. It seems quite toxic to ants.

There is a small ant nest somewhere by my back porch which results in a handfull of tiny ants wandering around. As I was spraying out the computer fan I managed to release some air away from the computer with the can tilted down (if you haven't played with canned air, this results in a very cold white mist). I noticed the ants stopped moving as the mist settled down on them. I played around a bit more and sure enough, it kills them dead in their tracks.

At first I thought I just froze them, but I'm not sure if this is the case. It takes very little amount of the mist to stop them. I managed to take a few out from a light spray about 1 meter away from the can. As a test, I lightly sprayed my hand and except for a few cold droplets, it wasn't that cold.

I also found just lightly spraying them with the air with the can upright didn't effect them. Only when I used the can upside down did it have any effect.

What's the deal?
#2
Old 10-18-2003, 03:17 AM
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Turning the can upside down is spraying microscopic droplets of the propellant (refrigerant) directly on them and killing them.
#3
Old 10-18-2003, 07:40 AM
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And the propellant is a hydrocarbon, not sure which, but most of them are toxic.
#4
Old 10-18-2003, 12:10 PM
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meaning that canned air isn't merely compressed air. Ok. But why not?
#5
Old 10-18-2003, 12:14 PM
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It is probably a lot colder to the ants. If you sprayed it on your hand you have the entire blood supply of your body to warm that area back up. For the ants, they have to contend with droplets the size of apples using their insect metabolism.
#6
Old 10-18-2003, 12:14 PM
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Because air doesn't compress well. It stays a gas at room temperature. Many chlorhydrocarbons and chlorofluorocarbons compress into a liquid very easily, therefore more can be put into a can than if plain air were used. CFCs are no longer used for this purpose, though.
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#7
Old 10-18-2003, 12:23 PM
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ah, I see. and as the internal pressure was reduced by spraying, more propellant would evalporate and create new pressure? I never thought about how propellants in aerosols worked.
#8
Old 10-18-2003, 12:49 PM
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Propane in tanks wors the same way. Most of it is liquid and boils off as some gas is let out. At a given temperature the pressure in the bottle is constant. That is why you cannot measure how much propane is left in the bottle with a pressure gauge.

Compressed natural gas (CNG) does not liquify and the pressures in the bottles are in the order of thousands PSI. A prassure gauge will tell you how much gas is left.
#9
Old 10-18-2003, 01:45 PM
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You are making the assumption that canned "air" in fact contains air. It does not.

In the old days canned "air" was freon or another CFC.
I'm not sure just what is in the can I have here (no statement of ingredients) but the label does have the following on it
  • never spary into an encolsed space
  • DELIBERATELY INHALING CONTENTS MAY BE FATAL
  • THIS PR0DUCT CAN BE IGNITED UNDER CERTAIN CIRCUMSTANCES
  • First aid: Innhalation Immediately remove to fresh air
Oh here I did find one ingredient listed
Contains difluroethane

Not air at all.
#10
Old 10-18-2003, 01:57 PM
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Rick - it seems that those statements are in reference to the propellant. It could be that inside the can is some liquefied difluoroethane AND some air. But why wouldn't they say that? I mean, it seems hard to believe that someone could sell a can of compressed difluoroethane and call it air. I'd think some governmental agency would require that it at least be labeled Canned "Air."
#11
Old 10-18-2003, 02:16 PM
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Despite what people call it, I've never seen a can of dust spray labelled "canned air".
#12
Old 10-18-2003, 02:41 PM
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The cans usually contain 1,1,1,2-tetrafluoroethane, C2H2F4. The boiling point is -26 degrees C, -15 degrees F. One little drop of it will make a little bit of your skin slightly colder, but there's a lot of heat in your hand and it quickly gets back to normal temperature. On the other hand, one little drop will take most of the heat out of an ant, killing it.
#13
Old 10-18-2003, 04:19 PM
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Quote:
Originally posted by sailor

Compressed natural gas (CNG) does not liquify and the pressures in the bottles are in the order of thousands PSI. A prassure gauge will tell you how much gas is left.
Also cooling natural gas to about -260F at normal pressure results in the condensation of the gas into liquid form, known as Liquefied Natural Gas (LNG).
#14
Old 10-18-2003, 04:26 PM
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CC My can says Dust Off, not canned air. I doubt very much if it contains any air. Shaking the can leads me to believe that it is mostly liquid in the can when full. Compressed air does not liquify at room temp.
#15
Old 10-18-2003, 04:35 PM
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Quote:
Originally posted by Wikkit
The cans usually contain 1,1,1,2-tetrafluoroethane, C2H2F4. The boiling point is -26 degrees C, -15 degrees F.
The boiling point changes with the pressure so your phrase is meaningless. The boiling point of any fluid is any temperature you want if the pressure is right. Well, not "anything" but you kow what I mean.

The boiling point is not -26C if it is at room temperature. If it is at room temperature then the temperature is a given and the boiling pressure will depend on that. Conversely, if you fix the pressure then it is the temperature which will be maintained constant by the constant pressure.
#16
Old 10-18-2003, 04:59 PM
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No shit, sailor. When spraying a liquid out of a can on earth, it can be safely assumed that the boiling point is given at atmospheric pressure. It's not meanigless, it's the only temperature that is meaningful given the situation.
#17
Old 10-18-2003, 06:21 PM
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Mine says "Compressed Gas" not"air." It also says "Liquid contents may cause severe burns (frostbite) on contact with skin." In addition, it has all the warnings about pressure, not exposing to heat and keeping out of reach of children.

It seems to me that if it can give big ol' me frostbite, it's probably cold enough to kill an ant. Just guessin' though.
#18
Old 10-18-2003, 06:38 PM
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Wikkit, sorry if I sounded rude which was not my intention. I did not understand what you meant and now I think I understand it and I thnk you are mistaken (if you mean what I think you mean). The liquid boiling in tha can is not at atn=mospheric pressure, it is at whatever pressure that liquid boils at room temperature. The gas coming out of the can is not liquid boiling, it is gas expanding from the pressure inside the can to the pressure outside the can.

If you are implying the gas comes out at -26C, I think you are mistaken. If you are not implying that then. . . I am still confused.
#19
Old 10-18-2003, 06:59 PM
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Inverting the can (creating a "very cold white mist" in the OP) will release liquid from the can. Some of the liquid will quickly boil, dropping the remaining liquid to -26C. Then the remainder will boil as it can remove heat from the environment. The liquid component of the mist hitting the ants is at -26.

If used upright, the gas coming out of the can will approach -26C if it is sprayed long enough. At some point you end up with a can of liquid at its boiling point with no appreciable pressure; the same thing will happen if you use propane gas from a tank too quickly.
#20
Old 10-18-2003, 07:27 PM
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Now I understand what you meant. Thanks for the explanation.
#21
Old 10-18-2003, 07:46 PM
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Ah, good. Sorry for snapping at you. Just don't say "your phrase is meaningless" to me often

Canned "air" is fun to play with, and I recommend it highly. It's not so cold to be really dangerous, and it's easier to get than liquid nitrogen. You can condense it on dry ice. I even spelled it without having to look it up. Here's the MSDS for anyone concerned.
#22
Old 10-19-2003, 03:00 PM
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So it sounds like my first thought was correct. "They done frozed"

I wasn't quite sure if it was the cold or something in the can that was doing it.

Wikkit: I agree, canned air is great fun to play with.
#23
Old 10-19-2003, 08:56 PM
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FYI -- Inhaling it makes your voice really, really deep. Dont tri it tho, cose it kill bransel.... what was I talking about?
#24
Old 10-19-2003, 09:41 PM
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Remeber, kiddos, use the same precautions while inhaling tetrafluorethane as you would helium or nitrous oxide. There's no oxygen, so you can't live on it. Make sure you get plenty of real air between uses.

And don't inhale directly from the can, since frostbite in your mouth or lungs would suck. Fill a baloon, and let it come to room temperature first.
#25
Old 10-19-2003, 09:47 PM
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Quote:
Originally posted by Wikkit
Fill a baloon, and let it come to room temperature first.
And don't do this either. Tetrafluoroethane and its relatives act on the brain in a manner similar to many anaesthetics. It would be all too easy to kill youself this way.
#26
Old 10-19-2003, 09:54 PM
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Really? Why isn't that mentioned in the MSDS? Most of them don't show rat LD-50 untill where it has displaced too much oxygen, rather than biochemical causes.
#27
Old 10-19-2003, 10:06 PM
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Quote:
Originally posted by Wikkit
Really? Why isn't that mentioned in the MSDS? Most of them don't show rat LD-50 untill where it has displaced too much oxygen, rather than biochemical causes.
Quote:
May be harmful by inhalation. Chronic exposure may cause reproductive damage. High levels may cause CNS damage. Contact with liquid may cause skin burns. Asphyxiant at high concentration.
From here.



Bolding mine.
#28
Old 10-19-2003, 11:37 PM
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Fascinating...how well does this stuff work on Cockroaches?
#29
Old 10-19-2003, 11:43 PM
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Fascinating...how well does this stuff work on Cockroaches?
#30
Old 10-20-2003, 03:10 AM
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Quite well, Ranchoth. I use it all the time to kill scary bugs, including cockroaches, when I can't find anything else to kill them with.
#31
Old 10-20-2003, 03:57 AM
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I killed a big ass spider with it last night. A REALLY big one.

Froze him solid. He didn't even know what hit him.

I would think it'd take out a <Scarface>f*ckin cock-a-roach</Scarface>
#32
Old 10-20-2003, 06:09 AM
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Ah, it's an insecticde sytle "Death-Spray"
#33
Old 10-21-2003, 03:04 PM
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Maybe some tiny rocks came out and hit the ants upside the head.
#34
Old 10-21-2003, 04:04 PM
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Oh sure, lieu, tiny to you.
#35
Old 10-21-2003, 04:12 PM
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So this stuff can kill insects? All I have to do is invert the can?

Definantly going to try this tonight to kill a few fruit flys bugging the hell out of me. Time to die you bastards!!!!

Wouldn't this be considered a very safe method of killing bugs? I mean, can injestion of this spray (on eating surfaces) stay present very long in room temp? Wouldn't it all just evaporate?
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#36
Old 10-21-2003, 04:47 PM
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badmana, it does evaporate very quickly. The only way it kills insects is by freezing them when you spray it on them directly out of the can.

Although under some conditions the gas and even the freezing liquid can be flammable. And when it burns, it seems to produce some pretty nasty fumes that burn the eyes and throat and whatnot. So maybe if they're really toxic, the fumes might kill bugs too! I think I smell a science project in the making.
#37
Old 10-21-2003, 06:49 PM
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Quote:
Originally posted by Q.E.D.
Bolding mine.
Any gas other than oxygen will cause CNS damage at high levels, due to oxygen deprivation.

Who needs a CNS anyway?
#38
Old 10-21-2003, 07:09 PM
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Having um...experimented with this stuff once or twice in my younger days, I can attest that the effects manifest themselves much too fast to be merely a product of anoxia. Or perhpas a different chemical was used back then. We're going back nearly 20 years.
#39
Old 10-21-2003, 08:30 PM
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Oh ah. You should have said that in the first place.

I never noticed any problems, but then I wasn't inhaling it in concentrated form. I usually just discharge a full can in a small room in the course of an evening's experiments... The smell is quite accurately described as 'ethereal', by the way.
#40
Old 10-21-2003, 09:01 PM
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My can of 1,1,1,2-tetrafluoroethane says it'll reduce the available oxygen in the air. I wouldn't want to spray so much of it that I could smell it.
#41
Old 10-21-2003, 10:45 PM
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Quote:
Originally posted by Q.E.D.
Having um...experimented with this stuff once or twice in my younger days, I can attest that the effects manifest themselves much too fast to be merely a product of anoxia. Or perhpas a different chemical was used back then. We're going back nearly 20 years.
Twenty years ago it would have probably been R-12, not a good thing to inhale.
#42
Old 10-21-2003, 11:04 PM
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Quote:
Originally posted by Rick
Twenty years ago it would have probably been R-12, not a good thing to inhale.
No, not at all. I don't know what it was, but I don't recommend trying to find out. i was young, stupid and lucky.
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