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| BC Pneumatics |
 Posted: 04/01/2007 20:52 PM Post subject: "How Much CO2 do I need?" |
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Donating Member
Joined: 18 Jan 2005
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For all those people out there looking for a rough idea of how much CO2 they will need for a chamber of any given size-
Just multiply the volume of your chamber (In Cubic Inches) by the constant 0.008475 This will give you the ounces of CO2 needed at 120psi, 73*f, needed for each chamber fill.
Example:
3.14 x (1/2) x 3"id x 36"length chamber= 254.34ci x 0.008475 = 2.155oz of CO2.
Edit by MrC:
Thanks to Davidvaini and Ragnarok for this calculation table:
http://www.spudfiles.com/forums/viewtopic,p,229345.html#229345
Alternative Word or PDF file available below.
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12g_co2_guide_v2_212.zip |
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Last edited by BC Pneumatics on 07/17/2007 1:07 AM; edited 2 times in total |
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| A-98 |
| Posted: 04/01/2007 21:44 PM Post subject: |
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Pussy Lover
Joined: 27 Apr 2006
Posts: 925
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how would you calulate it for different pressures, say 250, or 100.
thanks alot though, and i could definitely use this.
Last edited by A-98 on 04/01/2007 23:48 PM; edited 1 time in total |
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| BC Pneumatics |
| Posted: 04/01/2007 23:18 PM Post subject: |
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Donating Member
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| demilus |
| Posted: 04/09/2007 8:42 AM Post subject: |
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Staff Sergeant
Joined: 09 Apr 2006
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And I thought that I'd never use the stuff I learned in Chemistry class 
EDIT: I just realized, that the calculations need fixing.
It's pi*(radius of inner diameter)^2 * length of chamber = volume of chamber
NOT diameter of chamber * length of chamber
I think you knew this but you just forgot to write the equation. (254 is the volume of your example chamber, but 3*36, which equals 108, is not)
I'll delete this when it gets fixed
Fixed it, thanks 
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| randompkguy |
| Posted: 08/11/2007 16:48 PM Post subject: |
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Corporal
Joined: 27 Jul 2007
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| what if your regulator is graded in psi? is there a coefficient of expansion that you can multiply the psi by to get your final psi? (at 80 degrees)
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| ALIHISGREAT |
| Posted: 11/04/2007 7:05 AM Post subject: |
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Eternal Noob
Joined: 25 Aug 2007
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| what about if i wanted to fill to 100psi?
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| BC Pneumatics |
| Posted: 11/04/2007 9:14 AM Post subject: |
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Donating Member
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| You would need .83x as much.
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| ALIHISGREAT |
| Posted: 11/05/2007 13:28 PM Post subject: |
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Eternal Noob
Joined: 25 Aug 2007
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thanks, i found a 12g co2 adapter in the garge yesterday, it could be interesting to see what kind of pressures i can get in my 6mm sniper  also what if i want to work it out for different temperatures?
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| Ragnarok |
| Posted: 11/05/2007 14:03 PM Post subject: |
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Lord of Karma
Joined: 19 Dec 2006
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The ideal gas law again, I'm afraid.
A slightly different equation is this one:
Ounces of CO2 = Chamber volume in Cubic inches * Pressure in psi / (Temperature in Fahrenheit + 460) / 26.5
That includes temperature and pressure and gives practically the same answer.
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| ALIHISGREAT |
| Posted: 11/05/2007 14:19 PM Post subject: |
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Eternal Noob
Joined: 25 Aug 2007
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ahh thanks i will go and get my pencil! ok so at 10 degrees c i need 41.5oz to fill my 6mm to 250psi... which is quite alot 
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| Ragnarok |
| Posted: 11/05/2007 16:41 PM Post subject: |
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Lord of Karma
Joined: 19 Dec 2006
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| ALIHISGREAT wrote: | | ahh thanks i will go and get my pencil! ok so at 10 degrees c i need 41.5oz to fill my 6mm to 250psi... which is quite alot |
Wow, you have a 36.76 litre chamber.
Astounding for a 6mm sniper. I think you may have put the wrong numbers in, or mixed up the ordering of the functions. Are you sure you didn't go:
((Volume*Pressure/Fahrenheit)+460)/26.5
Rather than:
(Volume*Pressure/(Fahrenheit+460))/26.5
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| )DEMON( |
| Posted: 05/16/2008 11:15 AM Post subject: |
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Air head
Joined: 12 Mar 2006
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| So what if I had a chamber of 40 cubic inches and 12grams of liquid co2?
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| BC Pneumatics |
| Posted: 05/16/2008 11:25 AM Post subject: |
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Donating Member
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148psi @ 73*F, though I have to point out that the CO2 will no longer be in liquid form at this point.
Luckily gases are very easy to work with. Half the volume (20 CU) will give you twice the pressure (300psi), and increasing the chamber to 50CU, the pressure drops to 118psi.
For further manipulation...
P1V1=P2V2, where P= pressure and V= volume.
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| )DEMON( |
| Posted: 05/16/2008 12:05 PM Post subject: |
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Air head
Joined: 12 Mar 2006
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Thanks for the help 
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| BC Pneumatics |
| Posted: 05/16/2008 13:52 PM Post subject: |
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Donating Member
Joined: 18 Jan 2005
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| Well, most of the credit goes to Clapeyron, but I'm glad I could help.
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