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Co2 Fill Program

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Co2 Fill Program

Unread postAuthor: Davidvaini » Mon Jul 13, 2009 10:17 pm

So some of you may remember this chart that me and Ragnarok worked on together. Well he helped me with a lot of equations to put this together.

Well I decided it was pretty limiting because it was only at 70F and with a 12g co2 cartridge.

So I decided to make a computer application that helps people figure out what pressures they would be running at when filling with co2.


This can be useful if people are filling their cannons with co2 Inflators, remote lines, etc. It can also help people build a safe cannon.

I have seen many cases where a person will have a 10 inch PVC chamber that is 2 inches in diameter and they use a whole 12g co2 cartridge to fill it up. Now If they were to do this, it would exceed the pressure rating of the pvc.

Now I realize people could use gauges just to make sure, but sometimes gauges take away from the look of the cannon, especially when they are making military replicas.

BTW this is a contest entry for innovation.


Image

So tell me what you think!

Latest Version is 1.4
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Unread postAuthor: Davidvaini » Tue Jul 14, 2009 12:26 am

Uploaded a new version.

I added : after Cartridge size.
I also fixed the Issue of -108.76F and colder, making it say that Its Not a Gas at that state.

The equations used are as follows:

1.183 is the the molar ideal gas volume constant scaled according to the ideal gas equation to Kelvin, then converted to Rankine, converted to
cubic inches, divided by the molar mass of CO2, divided by 4,
multiplied by Pi, then multiplied by standard atmospheric pressure.

459.67 is for converting temperature from Fahrenheit to Rankine.

dblPSI = 1.183 * (dblTemp + 459.67) * dblGrams / (dblDiameter ^ 2 * dblLength)

Below is the vapour psi equation which is used to determine vapour pressures and to determine the state of the co2.
dblVapourPSI = 0.0000903 * dblTemp ^ 3 + 0.032572 * dblTemp ^ 2 + 5.155 * dblTemp + 292.54252

Again thanks to ragnarok for the help with the equations.
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Unread postAuthor: Ragnarok » Tue Jul 14, 2009 8:56 am

Tell you what David - if you wanted to be really slick, then you could add a term into the denominator of the "chamber pressure equation" that accounted for the volume of the CO2 bulb for a little bit more accuracy.
Unfortunately, I can't immediately tell you what this term would be, but I should be able to tell you by this evening (that being my evening) because I'll be able to make some measurements then.

I also remind people that the temperature here will be the internal temperature of the gas, which will not necessarily be the same as the ambient temperature (unless of course you've left time for it to equalise).
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: Davidvaini » Tue Jul 14, 2009 4:08 pm

Ragnarok wrote:Tell you what David - if you wanted to be really slick, then you could add a term into the denominator of the "chamber pressure equation" that accounted for the volume of the CO2 bulb for a little bit more accuracy.
Unfortunately, I can't immediately tell you what this term would be, but I should be able to tell you by this evening (that being my evening) because I'll be able to make some measurements then.

I also remind people that the temperature here will be the internal temperature of the gas, which will not necessarily be the same as the ambient temperature (unless of course you've left time for it to equalise).


Yeah I was thinking about that, but would the co2 bulb change with different size containers? If it changes constantly as the size of the container goes up, then that would be excelent, otherwise, I would have to have "increased accuracy on already known cases such as a 12g."
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Unread postAuthor: Ragnarok » Tue Jul 14, 2009 5:19 pm

Davidvaini wrote:Yeah I was thinking about that, but would the co2 bulb change with different size containers?

It scales pretty linearly.
Obviously, complete accuracy is nigh on impossible without precise volume measurements of chambers.

But if you change the denominator in the first equation to:
(dblDiameter ^ 2 * dblLength + (0.093 * dblGrams))

Then that will consider cartridge volume.
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Unread postAuthor: Davidvaini » Tue Jul 14, 2009 5:40 pm

Alright, thanks to rag for the update to calculate and consider cartidge volume.

Updated equation is as follows:

dblPSI = 1.183 * (dblTemp + 459.67) * dblGrams / (dblDiameter ^ 2 * dblLength + (0.093 * dblGrams))
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Unread postAuthor: Davidvaini » Wed Jul 15, 2009 1:15 pm

New update coming soon.

It will have the equation fix to consider cartridge volume, as well as some easier user interface and a new look!
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Unread postAuthor: Davidvaini » Fri Jul 17, 2009 2:35 am

Large UPDATE!

New Version, 1.4

It includes a file called release notes that can be opened via the program or with notepad or other .txt readable program.

It also includes information about the equations, ability to clear fields with the click of a mouse, and the ability to fix some user mistakes such as extra spaces before or after a number is typed.

The website address is not up yet, as I'm still working on my portfolio.

as always, tell me what you think!
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Unread postAuthor: Davidvaini » Sat Jul 18, 2009 4:58 pm

can someone download this new version and tell me if all the features work? I've been running into issues with files being downloaded from spudfiles.
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