# cu ft in a gas cylinder

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• posted on August 25, 2005, 2:01 am

does anybody know how a gas cylinder measuring 6" dia and 32" tall can have 80 cu ft of gas? how is this figured?

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• posted on August 25, 2005, 2:17 am
"mawtg" wrote

Yes ... the gas volume (in your case 80 cubic feet) is when it is at atmospheric pressure. By compressing the gas, you can make it fit into a smaller volume, but the pressure goes up accordingly.
Take a look at this page (hint ... I did a google search using the search term ' gas cylinder volume ' without the quotes):
http://www.engineeringtoolbox.com/compressed-air-storage-volume-22_843.html
Seems some old dead fellow (before he died) came up with Boyle's Law (betcha his name was Boyle).
Simply put, if you squeeze 80 cubic feet of gas at atmospheric pressure into a vessel with a volume of 40 cubic feet, the pressure in that vessel will be twice atmospheric pressure.
Hope this helps, but I'm still trying to figure out what this has to do with woodworking, other than it's a gas when it goes well!
Regards,
Rick

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• posted on August 25, 2005, 3:54 am
On Thu, 25 Aug 2005 02:17:20 GMT, "Rick M"

The Engineering Gods will smite you for that one.

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• posted on August 25, 2005, 7:20 pm
Roy <put an RP here> wrote:

Sir Arthur Conan Boyle concluded that such gas behavior was "elementary, my dear Watson, elementary!" < *groan* >

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• posted on August 25, 2005, 8:01 pm
Robert Bonomi wrote:

A watched Boyle never goes to pot. [old Swedish saying]     j4

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• posted on August 26, 2005, 12:00 am
wrote:

PUN FIGHT!!! (Starts off with a martial arts move from India, aka the Punjab...)

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• posted on August 25, 2005, 5:42 am
On Thu, 25 Aug 2005 02:17:20 GMT, "Rick M"

..it can also be liquified, depending upon the gas; e.g. propane. CO2 doesn't liquify under pressure, it becomes solid [dry ice.] Either way a lot can be fit into a little space.

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• posted on August 25, 2005, 6:11 am
Guess who wrote:

ISTR that CO2 will liquify under pressure at room temperature.
It won't condense into liquid at atmospheric pressure though, goes straight to solid.
Water does the same, gas to solid, solid to gas (sublimation) with no liquid phase at very low presssure.
--

FF

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• posted on August 25, 2005, 7:57 pm
On 24 Aug 2005 23:11:13 -0700, snipped-for-privacy@spamcop.net wrote:

When you're right, you're right. Trying to make the point, I said something dumb. It happens.

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• posted on August 25, 2005, 9:11 pm
There is a phase diagram of CO2 at http://www.science.uwaterloo.ca/~cchieh/cact/c123/phasesdgm.html , with explanation.
Steve
wrote:

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• posted on August 26, 2005, 12:00 am
snipped-for-privacy@spamcop.net wrote:

Actually that isn't true. The properties of water are quite different from those of carbon dioxide. Sublimation of water also occurs at normal atmospheric pressures.

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• posted on August 26, 2005, 1:25 am
George E. Cawthon wrote:

Sure it is. Water does just that.

I didn't say that water could did sublimate at normal atmospheric pressure. The vapor pressure of water over ice is non zero, same as for a lot stuff.
I said water goes gas to solid and solid to gas (sublimation) with no liquid phase at very low presssure, which is true. Carbon dioxide does the same, at atmospheric pressure, gas to solid, solid to gas, with no liquid phase.
--

FF

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• posted on August 26, 2005, 2:04 am
snipped-for-privacy@spamcop.net wrote:

I know you didn't. You should have.

Not true, doesn't have to be very low pressure. It happens all the time at atmospheric pressure.

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• posted on August 26, 2005, 3:25 am

Certainly it *is* true. Or do you claim that water does *not* pass directly between the solid and gaseous phases at very low pressures?
He stated that this occurs at very low pressures. That is true.
He did *not* state that it does *not* occur at normal pressures. You seem to be under the impression that he did.

Yes, thank you, we know that already. Who claimed that it didn't?
--
Regards,
Doug Miller (alphageek at milmac dot com)

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• posted on August 26, 2005, 6:42 am
Doug Miller wrote:

Like to argue for the sake of it, Doug?
Inclusion of the stipulation of "very low pressure" in his statement implies that very low pressures are needed. Otherwise why throw it in?

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• posted on August 26, 2005, 11:42 am

Ummm, no, that would be *you* in this thread, I think...

Dunno. Why ask me? Ask him. I'm just pointing out that he didn't make the claim you're imputing to him.
--
Regards,
Doug Miller (alphageek at milmac dot com)

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• posted on August 26, 2005, 7:52 pm
George E. Cawthon wrote:

Note also the 'stipulation' of "without a liquid phase".
Sort of like CO2 at atmospheric pressure, eh? At very low pressure water behaves somewhat like the way CO2 does at atmospheric pressure. Of course that was always clear from the context.
--

FF

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• posted on August 25, 2005, 11:50 am

Not correct. CO2 cannot be *solidified* under pressure unless the temperature is below -57 degrees C.
The triple point of CO2 is -57 deg C and 5.1 atmospheres: it can exist as a solid, liquid, or gas at that temperature and pressure. It cannot exist in the solid phase above -57 degrees, nor in the liquid phase below that point, regardless of pressure.
--
Regards,
Doug Miller (alphageek at milmac dot com)

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• posted on August 25, 2005, 9:54 am

as does the temperature

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• posted on August 25, 2005, 9:57 am

...errrrmmm...is this why we 'boyle' water?
...could be where that word came from...
A faraday keeps the doctor away?
Back to sleep.