# 500g Liquid CO2 = what volume of CO2 gas?



## John P Coates (1 May 2014)

Hi Folks,

Does anyone know how to convert from liquid CO2 to CO2 gas? No, the answer is not a regulator!

I have a JBL 500g cylinder and I would like to estimate how long it will last. I simply need to know what this weight of liquid CO2 is equivalent to when it converts to gaseous CO2. It is the volume of CO2 gas that I need to know. The rate at which the CO2 gas is being used can readily be estimated. I realize that a few similar questions have been posed before on this topic but usage is obviously a function of desired end point (in ppm CO2), bubble rate, etc.

BTW, cylinder pressure is typically 60bar.

Can anyone help?

Thanks in advance.

JPC


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## Mr. Teapot (1 May 2014)

Hi John, on the back of my disposables is says: 390g / 60 ltr, and the 600g / 110 ltr.


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## John P Coates (1 May 2014)

Mr. Teapot said:


> Hi John, on the back of my disposables is says: 390g / 60 ltr, and the 600g / 110 ltr.


Hi Mr T.

Thanks a lot. Very useful.

I trust they are the JBL disposables. Do you know what pressure they are at? Your regulator probably indicates the disposable cylinder pressure. Depends on which regulator you are using.

JPC


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## Mr. Teapot (1 May 2014)

Not JBL Disposables - JBL will just rebrand the welding cylinders and add on their margin (£16 for 600g vs. JBL £25 for 500g). I think (not certain) they may use a different thread size to tie in their users.

I don't have a cylinder pressure guage, only working pressure on mine as it's a cheapo regulator for about £20 ( never had any problem with it so can't justify paying out for a nifty dual stage reg).[DOUBLEPOST=1398973871][/DOUBLEPOST]600g Cylinder is at 36bar - written on label


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## Mr. Teapot (1 May 2014)

Ah, just realised, you have the small refillable JBL tank not the 500g JBL Disposables.


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## John P Coates (1 May 2014)

Mr. Teapot said:


> Ah, just realised, you have the small refillable JBL tank not the 500g JBL Disposables.


Hi again,

Yes, that's right. I have a JBL 500g refillable cylinder.

Nevertheless, your information is a good guide.

JPC


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## Mr. Teapot (2 May 2014)

Nice little cylinder, I have to hide my gas in the cabinet - my other half would go mental if she knew I had compressed gas cylinders in the house - especially with'welding gas' written on them! (I guess I could print out labels with 'natural carbon supplement' with lots of nice pictures of green plants on them). Oh by the way, the 36bar is at 0c... If this info is important in your calculations?


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## ian_m (2 May 2014)

From JBL, 500gr of CO2 gives 254litres of CO2 at atmospheric pressure.
http://www.jbl.de/en/aquatics-freshwater-products/detail/2353/jbl-proflora-m500-bottle#faq

Given by 1 mole of CO2 is 44gr (12gr for C and 16 x 2 gr for O2).
1 mole occupies 22.5litres at room temp and pressure.
Thus 500gr occupies 500/44 * 22.5 = 255 litres.


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## Mr. Teapot (2 May 2014)

That's interesting - why do you think the disposable bottles have 110litres for 600g written on them? That's quite a difference in volume.


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## John P Coates (2 May 2014)

ian_m said:


> From JBL, 500gr of CO2 gives 254litres of CO2 at atmospheric pressure.
> http://www.jbl.de/en/aquatics-freshwater-products/detail/2353/jbl-proflora-m500-bottle#faq
> 
> Given by 1 mole of CO2 is 44gr (12gr for C and 16 x 2 gr for O2).
> ...


That answers my question. Many thanks! I will also check the link on my laptop. Right now, I'm using a Tab and trying to follow the link makes no mention of the 254 litre figure. I also appreciate the fact that you have reminded how to do the calculation. Good on ya![DOUBLEPOST=1399020346][/DOUBLEPOST]





Mr. Teapot said:


> I have to hide my gas in the cabinet - my other half would go mental if she knew I had compressed gas cylinders in the house - especially with'welding gas' written on them! (I guess I could print out labels with 'natural carbon supplement' with lots of nice pictures of green plants on them).


Mr T,

I had a good laugh when I read this! Thanks for that.

JPC


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## John P Coates (2 May 2014)

Mr. Teapot said:


> That's interesting - why do you think the disposable bottles have 110litres for 600g written on them? That's quite a difference in volume.


I guess it's primarily to do with cylinder pressure. My JBL 500g refillable is at 60bar at room temperature and your disposable cylinder is 600g at 36 bar at 0 degrees C. So, the JBL pressure is 67% higher than your cylinder. Chemistry is not my area of expertise!


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## ian_m (2 May 2014)

John P Coates said:


> I guess it's primarily to do with cylinder pressure. My JBL 500g refillable is at 60bar at room temperature and your disposable cylinder is 600g at 36 bar at 0 degrees C. So, the JBL pressure is 67% higher than your cylinder. Chemistry is not my area of expertise!


Can't be. It doesn't matter if you store 500gr @ 60bar or 500gr @ 36bar or 500gr at 1bar (atmospheric) it's still 500gr regardless of pressure. 500gr will always be 255litres at 1 atmosphere and 600gr will be 255*600/500 = 306litres.


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## Mr. Teapot (2 May 2014)

Would temperature be a factor? Would raising the bottle temperature to room temperature raise the bottle pressure to 60bar and the volume of the gas if at atmospheric pressure to 306 litres? Not really important, just mildly interested in the reason for the 110 litres printed on the bottle.


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## John P Coates (2 May 2014)

ian_m said:


> Can't be. It doesn't matter if you store 500gr @ 60bar or 500gr @ 36bar or 500gr at 1bar (atmospheric) it's still 500gr regardless of pressure. 500gr will always be 255litres at 1 atmosphere and 600gr will be 255*600/500 = 306litres.


You see, I was right when I said 'Chemistry is not my area of expertise'! So, what could be the correct answer to Mr Teapot's question?[DOUBLEPOST=1399038250][/DOUBLEPOST]





Mr. Teapot said:


> Hi John, on the back of my disposables is says: 390g / 60 ltr, and the 600g / 110 ltr.


Could it be that the weights quoted are the weights of the empty cylinders? Perhaps you could ask the manufacturer/supplier? Just interested.


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## MikeC1408 (6 May 2014)

Mr. Teapot said:


> Nice little cylinder, I have to hide my gas in the cabinet - my other half would go mental if she knew I had compressed gas cylinders in the house - especially with'welding gas' written on them!



Lol , one of the rules of working from home for my job is you have to agree to supply your own fire extinguisher for H&S reasons. 

Doesn't say is has to have to cone fitted and be available to put a fire out......lol


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## Yo-han (6 May 2014)

Mr. Teapot said:


> Would temperature be a factor? Would raising the bottle temperature to room temperature raise the bottle pressure to 60bar and the volume of the gas if at atmospheric pressure to 306 litres? Not really important, just mildly interested in the reason for the 110 litres printed on the bottle.



Only the temperature when outside the bottle makes a difference. As Ian mentioned, 500gr = 500gr. But 500gr of CO2 gas in the air at 20C is different than 500gr of CO2 at 25C. The warmer it is, the larger the volume.


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