# Air dusters

By swker98 ยท 13 replies
Jul 20, 2006
1. hi guys

jsut picked up and air duster

i never used one of these before, so i used it to clean my keyboard and tghe bottle got REALLY cold

is this normal

also if i spray it for more then a minute this ice comes out

exactly y is this

2. ### Kevin16TS RookiePosts: 92

That is because you probably SHOOK it or TURNED IT UPSIDE DOWN. That is because the "air" is compressed to some hundreds of times its volume. It comes out really fast and that makes it freeze.

the gas in your can is actually not air, it will cause brain damage when directly inhaled and i would not reccomend dispensing a lot of it indoors. the coldness is actually caused by the gasses inside, which are in ther liquid states on account of the high pressure.

4. ### CMHTechSpot ChancellorPosts: 2,039   +9

Lol.... This is funny.

The temp goes down because of the formula PV/T = PV/T. Any high school student doing Physics will tell you that.

P = Pressure (the contents of the can is under pressure)
V = Volume (the can has space)
T = Temperature (in Kelvins, which is just Celcius + 273)

The left hand side (of the equation) can be considered the conditions of the can before usage, and the right hand side (of the equation) is the conditions of the can after usage.

Anyway, the volume of the can is constant (so the contents are also constant). As you spray, the pressure drops. Therefore, for the left hand side to equal the right hand side, the temperature drops too. The more you spray, the lower the pressure drops, and the lower the temp drops. And since you sprayed non-stop for a considerable amount of time, it goes below 0C, and ice forms

And yes, I know my can contains tetraflouro ethane, and its not a real good thing to have breathing in in large quantities. I'm not sure why you'd use one to clean your keyboard, since a brush or something will do the same job. I use mine to clean dust off my heatsinks.

5. ### TedsterTechspot old timer.....Posts: 6,000   +15

you gotta be careful too. You don't want to thermally shock your stuff either. Don't get freezing cold gas to condensate water and freeze it on your hot components. Spray when the system is unplugged, offline, and reached room temps.

6. ### CMHTechSpot ChancellorPosts: 2,039   +9

you shouldn't be able to condensate water.... but either way, I don't think its a good thing spraying one particular part too long. Also, I usually wait for the can to heat up a little before spraying a long spray.

7. ### N3051MTS EvangelistPosts: 2,115

Hmm? i thought Kelvins were -273`C?

I havn't bought a can for a while.. ever since my dad bought one of those electric air compressors to pump up the car tyres

8. ### i_am_a_newbieTS RookiePosts: 170

-273C = Absolute zero, which is 0 K. So K = C+273 is correct.

Anyways, I have had water condense when spraying the can upside down(I emptied an entire bottle for 'educational' purposes:haha: ), short bursts with the can rightside up is the way I clean my heatsinks. For my keyboard I just attach a tiny nozzle(self-built) to my vacuum cleaner(it doesn't work so well on heatsinks, though).

9. ### Kevin16TS RookiePosts: 92

How do u think superman can blow out ice?

10. ### CMHTechSpot ChancellorPosts: 2,039   +9

Superman does blow out ice. I can also blow out ice. Its simple really....

11. ### N3051MTS EvangelistPosts: 2,115

Wow.. so we do have some superheros hiding here too.. please, show us

12. ### CMHTechSpot ChancellorPosts: 2,039   +9

Blow ICE? Well, all you have to do it compress the air in your lungs, and let them all our suddenly. This causes the same effect seen with an air can, and if you do it fast enough, you'll be blowing ice.

PV/T = PV/T

1 = 1 ?

14. ### CMHTechSpot ChancellorPosts: 2,039   +9

Well, if you want to be technical:

(P1)(V1)/(T1) = (P2)(V2)/(T2)

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