Air dusters - Why R134 ?

Hi all,

I've always wondered why those air duster cans use R134 or simmilar
refrigerants, etc instead of some other chemical or simply air ? (or even
CO2)

What also puzzles me is why it's illegal to vent R134 into the atmosphere
from your air conditioner, but you can buy sprays cans full of it at any
electronics store ?

Anyone have any theories here ?

Chris

Skeleton Man wrote:

> Hi all,
>
> I've always wondered why those air duster cans use R134 or simmilar
> refrigerants, etc instead of some other chemical or simply air ? (or even
> CO2)
>
> What also puzzles me is why it's illegal to vent R134 into the atmosphere
> from your air conditioner, but you can buy sprays cans full of it at any
> electronics store ?
>
> Anyone have any theories here ?
>
> Chris

Air duster cans containing just plain air are available ... but don't buy
them: they quickly run out of pressure because the contents is just
compressed gas. Some gasses (like R134 and "Freon") liquify at reasonably
low pressure, so a can of R134 is mostly liquid that gradually returns
to gaseous state as it is allowed to escape. Result: a can of R134 gives
much more gas than a same-size can of air (which doesn't liquify at can
pressure), and the nozzle pressure remains constant until the last bit of
liquid in the can boils off.

CO2 liquifies at about 800psi. It would do the job if supplied in a
vessel capable of withstanding that pressure. The small CO2 cartridges
used to pressurize seltzer bottles or air guns might serve ... but
would be awkward to use with an 800psi gas stream. A regulator would
solve that problem, but at unacceptable cost.

Propane liquifies at reasonable pressure and is used as a propellant
in aerosol cans ... but you wouldn't want to use it anywhere there is the
possibility of ignition.

Bryce

>Air duster cans containing just plain air are available ... but don't buy
>them: they quickly run out of pressure because the contents is just
>compressed gas. Some gasses (like R134 and "Freon") liquify at reasonably
>low pressure, so a can of R134 is mostly liquid that gradually returns
>to gaseous state as it is allowed to escape. Result: a can of R134 gives
>much more gas than a same-size can of air (which doesn't liquify at can
>pressure), and the nozzle pressure remains constant until the last bit of
>liquid in the can boils off.

Thanks for the info. My concerns about air duster gasses are purely cost -
all the ones I've seen are tetrafluoroethane (R134a) and cost about $10/can!
I figured maybe there was a cheaper alternative to this.

I was thinking an air compressor would work, but that's likely too much
pressure and moisture. The main thing I use air dusters for is cleaning
boards and fans/air intake.

Chris

"Skeleton Man" <invalid@guestwho.com> wrote in message
news:SOidnU9h0aWXHMHVnZ2dnUVZ_r_inZ2d@wightman.ca. ..
> >Air duster cans containing just plain air are available ... but don't buy
>>them: they quickly run out of pressure because the contents is just
>>compressed gas. Some gasses (like R134 and "Freon") liquify at reasonably
>>low pressure, so a can of R134 is mostly liquid that gradually returns
>>to gaseous state as it is allowed to escape. Result: a can of R134 gives
>>much more gas than a same-size can of air (which doesn't liquify at can
>>pressure), and the nozzle pressure remains constant until the last bit of
>>liquid in the can boils off.
>
> Thanks for the info. My concerns about air duster gasses are purely cost -
> all the ones I've seen are tetrafluoroethane (R134a) and cost about
> $10/can!
> I figured maybe there was a cheaper alternative to this.
>
> I was thinking an air compressor would work, but that's likely too much
> pressure and moisture. The main thing I use air dusters for is cleaning
> boards and fans/air intake.
>
> Chris
>
I always use a small air compressor with 18 l air tank, cost only 80$. The
air pressure is adjustable, higher than cans, but low enough to avoid any
problem. And finally, a compressor allows to really clean fans and
radiators, which is not the case with cans.

On Sat, 21 Jun 2008 00:18:22 -0400, "Skeleton Man"
<invalid@guestwho.com> wrote:

>>Air duster cans containing just plain air are available ... but don't buy
>>them: they quickly run out of pressure because the contents is just
>>compressed gas. Some gasses (like R134 and "Freon") liquify at reasonably
>>low pressure, so a can of R134 is mostly liquid that gradually returns
>>to gaseous state as it is allowed to escape. Result: a can of R134 gives
>>much more gas than a same-size can of air (which doesn't liquify at can
>>pressure), and the nozzle pressure remains constant until the last bit of
>>liquid in the can boils off.
>
>Thanks for the info. My concerns about air duster gasses are purely cost -
>all the ones I've seen are tetrafluoroethane (R134a) and cost about $10/can!
>I figured maybe there was a cheaper alternative to this.
>
>I was thinking an air compressor would work, but that's likely too much
>pressure and moisture. The main thing I use air dusters for is cleaning
>boards and fans/air intake.


An air compressor can have a valve to regulate pressure, or
you could choose one that just doesn't produce high flow
rate, thus causing the pressure to drop quickly at any
distance from the nozzle.

Moisture is not an issue. Don't use a compressor that puts
oil in the lines for power tool use.

You don't actually need to use compressed air, a small paint
brush will do fine and costs about $1. You can get empty
cans with a refill port but they won't last nearly as long
as a pre-filled can of *air* before having to be refilled
again.

http://www.shoplet.com/office/db/g15978.html

Another idea is a CO2 cannister like you'd find on a
paintball gun, then you just need the fittings, valve and
hose. Surely somebody has that, you'd just have to hunt
down the parts or possibly make it yourself by buying the
separate fittings and hose then crimping it together.

"Skeleton Man" <invalid@guestwho.com> wrote in message
news:SOidnU9h0aWXHMHVnZ2dnUVZ_r_inZ2d@wightman.ca. ..
| >Air duster cans containing just plain air are available ... but don't buy
| >them: they quickly run out of pressure because the contents is just
| >compressed gas. Some gasses (like R134 and "Freon") liquify at
reasonably
| >low pressure, so a can of R134 is mostly liquid that gradually returns
| >to gaseous state as it is allowed to escape. Result: a can of R134 gives
| >much more gas than a same-size can of air (which doesn't liquify at can
| >pressure), and the nozzle pressure remains constant until the last bit of
| >liquid in the can boils off.
|
| Thanks for the info. My concerns about air duster gasses are purely cost -
| all the ones I've seen are tetrafluoroethane (R134a) and cost about
$10/can!
| I figured maybe there was a cheaper alternative to this.
|
| I was thinking an air compressor would work, but that's likely too much
| pressure and moisture. The main thing I use air dusters for is cleaning
| boards and fans/air intake.

Look into one of the small (and portable) air compressors used by air brush
artist. Most have a dehumidifier and dust filters.

Alternatively pick up one of those portable tanks at the local aftermarket
auto parts stores (some wal marts have them as well) they can be filled at
most gas stations or you can use a 12 volt compressor (also available at
parts store and wal mart)