why C02

Mathias Koerber said:

and nor compressed air (for those cartridge inflators)..

What makes CO2 the more desirable gas for this use?

just curious...

It's easy to get from compressed air, becuase it has a
fairly high boiling point. Also easy to store either as a
solid or a liquid.

Mathias Koerber said:

and nor compressed air (for those cartridge inflators)..

What makes CO2 the more desirable gas for this use?

Couple of things: CO2 is in the cannister as a liquid, when
it's released and turns to gas, it expands. CO2 maintains a
constant pressure until it's empty, unlike air which will
decrease pressure as it empties. Also iirc, in a container
of the same size, you get something like 17x more volume
from CO2 than you would with compressed air, which is why
one of those little cylinders can fill a tire. If you've
ever tried to fill a car tire with a 5lb air tank, you know
how poorly that works. On the other hand, offroaders carry
CO2 tanks to air up their tires for the ride home. A 10lb
tank can fill 33" tires from 12psi to 30psi around 4-5 times
(20 tires).

"Ed J." <[email hidden]> wrote in message
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[...]

Quoted message said:

Also iirc, in a container of the same size, you get
something like 17x more volume from CO2 than you would
with compressed air, which is why one of those little
cylinders can fill a tire.

It's such a shame you can't breathe CO2 when scuba diving.
You could stay under for *hours*.

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DRS said:

"Ed J." <[email hidden]> wrote in message
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[...]

Quoted message said:

Also iirc, in a container of the same size, you get
something like 17x more volume from CO2 than you would
with compressed air, which is why one of those little
cylinders can fill a tire.

Quoted message said:

It's such a shame you can't breathe CO2 when scuba diving.
You could stay under for *hours*.

You know, if you *DID* use CO2 for diving, you probably
*WOULD* stay under for hours. If not years, if you catch
my drift...

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"DRS" wrote: t's such a shame you can't breathe CO2 when
scuba diving. You could stay under for *hours*. ^^^^^^^^^^^^
Actually, you could stay under *forever*.

BTW, a very important reason CO2 is used for compact tire
inflators is that it is there. The cartridges are used for
pellet pistols, seltzer bottles, and who knows what, so they
are available.

Leo Lichtman said:

BTW, a very important reason CO2 is used for compact tire
inflators is that it is there. The cartridges are used for
pellet pistols, seltzer bottles, and who knows what, so
they are available.

Let's not lose sight of the correct answer Ed gave and that
is that CO2 is a liquid at these pressures and occupies a
tiny volume just as water does in comparison its gaseous
form (steam). Air cannot be reduced to liquid except at
impractically high pressures. Because refrigerants, like
ammonia or freon are borderline liquid/gases at atmospheric
temperatures and pressures, they lend themselves to phase
change cooling as they are compressed and expanded. You'll
notice that CO2 cartridges freeze when the contents are
released. That results from phase change of liquid to gas.
Of course just expanding a gas results in cooling but no
where near what phase change produces. Some gases cannot be
liquefied and are ill suited to these applications.

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Jobst Brandt [email hidden]

All gases can be compressed and refrigerated to condense into liquids and/or solids. Atmospheric gases like nitrogen and oxygen cannot be liquified at temperatures/pressures we would be content with...you would have to keep your cartridges deeply refrigerated, not something you would want to do on a ride. At normal temperatures, there is no container strong and light that could keep oxygen or nitrogen liquified.

But now CO2...its quite an odd mgas as it will exist as a solid or gas at normal pressures/temperatures or as a mix of gas and liquid of you get the pressure up to 800-1000 PSI(a). Since it can exist as a solid at atmospheric pressures, filling foil-sealed bottles is quite easy. Keep the containers cold on dry ice and weigh the contents. When the net weight of CO2 is right, crimp the seal. Voila, a 12, 16 or what ever mass of CO2 is sealed and easily used.

I've refilled 16 gram cartridges using liquid nitrogen to deposit CO2 into the cartridge. When I weighed 16 grams, I installed my inflator, sealed it and was done. Now I use 12 gram ones at $.50 per each, its far easier. But when the LBS was charging $4.50 for a 16 gram, flats were far too expensive.

Mathias Koerber said:

and nor compressed air (for those cartridge inflators)..
What makes CO2 the more desirable gas for this use? just
curious...

In days of old, our refillable gonfleurs used nitrogen.

I think you'll find that CO2 is dirt cheap and ubiquitous
because the cartridges also fit BB guns, not because small
town hardware stores care all that much about cylists.

--
Andrew Muzi www.yellowjersey.org Open every day since 1
April, 1971

Mathias Koerber said:

and nor compressed air (for those cartridge inflators)..

What makes CO2 the more desirable gas for this use?

just curious...

A greater amount of CO2 than air can be contained in a
cartridge of a given volume at the same pressure and
temperature.
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"A Muzi" <[email hidden]> wrote in message
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Quoted message said:

Mathias Koerber said:

and nor compressed air (for those cartridge inflators)..
What makes CO2 the more desirable gas for this use? just
curious...

In days of old, our refillable gonfleurs used nitrogen.

I think they should use helium.

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Mathias Koerber said:

What makes CO2 the more desirable gas for this use?

CO2 can exist as a liquid below 31 C, and since liquid is
much more dense than gas, lots of CO2 can be stored in a
given sized container. Nitrogen's critical temperature is
-147 C, making its use impractical without refrigeration.

The other nice thing about CO2 is it's essentially inert.

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