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Capacity of O2 gas in a cylinder
- Thread starter jor1492
- Start date
Maybe you remember this from somewhere
Boyle's Law is a pretty good start as long as you're happy with an answer that's there or thereabouts and you're going to take the oxygen out reasonably slowly (or at least let it recover to 70F before you attempt to measure its volume. Otherwise:
A.
Oxygen isn't quite an ideal gas so, at 2524 psi and 70F, you'll find you can get nearly 6% more of it into a cylinder than Boyle's law would lead you to expect (the sweet spot is at about 2200 psi - after that it slowly starts getting closer to the ideal). Other gases behave differently (so with air at that pressure, a cylinder holds one or two percent less than Boyle's Law predicts)
If you expand the oxygen quickly, it will come out cold and take up quite a bit less volume than you might otherwise expect until it warms back up again.
If you expand the oxygen quickly, it will come out cold and take up quite a bit less volume than you might otherwise expect until it warms back up again.
A.
- Thread starter
- #4
georgeverghese
Chemical
Since O2 is an non polar gas, try one or more of these EOS and see which one suits you :
a) The Redlich Kwong equation
b) The Benedict Webb Rubin equation
Methods for these can be found in 6th edition of Perry Chem Engg Handbook in the section on physical properties estimation - a lot of this material (especially the BWRS EOS) is excluded in the 7th edition. Since O2 is paramagnetic, would suspect it deviates more than say nitrogen from z=1 at high pressures.
a) The Redlich Kwong equation
b) The Benedict Webb Rubin equation
Methods for these can be found in 6th edition of Perry Chem Engg Handbook in the section on physical properties estimation - a lot of this material (especially the BWRS EOS) is excluded in the 7th edition. Since O2 is paramagnetic, would suspect it deviates more than say nitrogen from z=1 at high pressures.
Refprop.exe from NIST says that the compressibility factor is 0.93759 at your conditions (about 6% off ideal like zeusfaber said)
[bold]David Simpson, PE[/bold]
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
[bold]David Simpson, PE[/bold]
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
LittleInch
Petroleum
There's also the question of what volume or "standard" volume conditions you're expressing this in. Makes a difference as well.
There is sadly no universal "standard" conditions to which you reference back to. This has been debated a LOT on these pages so I won't start it up again now.
Seems to be a very precise pressure reading....
Also depends on what is your end pressure if you're trying to work out usable volume
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
There is sadly no universal "standard" conditions to which you reference back to. This has been debated a LOT on these pages so I won't start it up again now.
Seems to be a very precise pressure reading....
Also depends on what is your end pressure if you're trying to work out usable volume
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
- Thread starter
- #10
Again , thanks guys. Finally I am using the boyle law with the compresibility factor "z". Also I will do a spreadsheet to run the Redlich kwong equation to have a closer value.
Just to know in what source Can I get the z values for different kinds of gases, like N2,Ar, Helium, Air in different pressures?
Just to know in what source Can I get the z values for different kinds of gases, like N2,Ar, Helium, Air in different pressures?
EmmanuelTop
Chemical
Try the attached spreadsheet from ChE Forums - it calculates Z based on several cubic equations of state (EOS). You need to provide fluid-specific properties (critical pressure, critical temperature, acentric factor, molecular weight - you can get all these in textbooks or online) and operating conditions (pressure, temperature).
You can also build your own spreadsheet because the EOS' are not that complex.
Dejan IVANOVIC
Process Engineer, MSChE
You can also build your own spreadsheet because the EOS' are not that complex.
Dejan IVANOVIC
Process Engineer, MSChE
NIST web site is pretty easy and ... no errors.
select O2
print the whole table for your office wall paper.
select O2
print the whole table for your office wall paper.
georgeverghese
Chemical
Typically O2 from a cryo column will contain a small amount of Ar (less than 1% v/v from memory), so you'll need to apply the mixing rules suggested in Perry to get to mix values for the critical props for the RK / SRK method if you want better accuracy.
LittleInch
Petroleum
Zeus. Not nosy, We know each other quite well and he introduced me to this forum. In honour of the many posts I hadread before I knew who he was and a lack of imagination I kind of adapted his handle. We generally agree on technical issues so isn't too confusing. I like the name now.
I hate it when nominal figures get converted exactly and not rounded.
No one bit on the standard volume question though....
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
I hate it when nominal figures get converted exactly and not rounded.
No one bit on the standard volume question though....
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
I took the name from the Big Inch Pipeline, which also had a Little Inch Pipeline (actually some 200 miles longer) built to transport oil along the US east coast in order to avoid risks of German U-boat activity during WWII.
I took the BigInch name from the Big Inch pipeline built along the US east coast during WWII to avoid attacks from German U-Boats on the ocean shipping route from Texas to New Jersey. Coincidently ... it also had a Little Inch counterpart pipeline, which was actually 200 some miles longer.
We usually agree on everything ... eventually. Well ... except for the spelling of certain words.
We usually agree on everything ... eventually. Well ... except for the spelling of certain words.
zeusfaber, OK I see you're military, so here's the historic link.
jor1492, sorry for jacking your thread.
jor1492, sorry for jacking your thread.
LittleInch
Petroleum
Never knew that. Thought big inch was just general slang for large diameter long distance pipeline, esp in the US.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
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