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# At room temperature, how much pressure does a 12g CO2 cartage output? Answered

...and can it be controlled by a 10 bar rated 12v solenoid valve?

I'm thinking about making a remote controlled Co2 confetti cannon and I'm planning on using a 12v 3/8" solenoid rated at 0-10 bar which will be operated by a relay controlled by a networked arduino. I realise that they run at different pressures depending on their temperature, but this will be used indoors.

Thanks!

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## Discussions

I just noticed this:
https://www.instructables.com/id/Easy-CO2-powered-Squib-for-Self-contained-Blood-an/
in the related panel there. ------>
The author, RavingMadStudios,  does not seem to be too concerned about excessive pressure, and he's just using vinyl tubing.

It may be that the bike-tire inflator has something resembing a regulator inside it, or that there is just a really big pressure drop across it.

Anyway, that might be worth considering, especially if the thing you are using to connect to the cartridge is one of those bike-tire inflators.

The vapor pressure of CO2 at room temperature, around 25 C or 77 F, is around 850 psi, or about 56 bar, and that number is a lot larger than the rating of your valve.

For larger bottles of CO2, the usual trick is to use a pressure regulator.
http://en.wikipedia.org/wiki/Pressure_regulator
For example, those little portable CO2 supplies for air tools, do exactly that: use a regulator to drop the pressure in the bottle from 850 psi, to around 50 to 150 psi, which is what the air tool wants. Here is what one of those artifacts looks like:
http://www.lowes.com/pd_82384-61735-J-6901-101_?PL=1&productId=3113951

However, for one of those dinky little 12g cartridges, it might work well enough to just to give it some volume to expand into.  The molecular weight of CO2 is about 44g/mol, so 12g is 0.27 mol.  At standard temperature and pressure that would occupy a volume of about (22.4 L/mol)*(0.27 mol) = 6.1 L.  That's at room temperature  and 1 bar.  If instead it were compressed into a one liter volume (still at room temperature), then the pressure would be 6.1 bar.  Assuming there was some air at STP already inside that 1 liter volume, then I think that's 6.1+1 = 7.1 bar.

If you gave it 2 liters to expand into, then what would that be? 3.05+1 = 4.05 bar?

Schedule 40 PVC might be good choice for the expansion chamber,
http://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d_796.html
and the fittings/adapters for that would be easy to find. You could even put a pressure gauge on it.

Be sure you do the math right, especially for calculating the volume of the expansion chamber, because I would feel bad if this thing went all explode-y on you.  I think a 1 meter length of 2-inch diameter PVC, will have a volume of about 2 liters, although you should check this math yourself.  Also try a big volume first, e.g. 2 or 3 liters, and pay attention to what the pressure gauge says.    Doing that as a first step should  give you some confidence if you want to try a smaller chamber with bigger pressure.

More on bottled CO2 here:
http://www.warpig.com/paintball/technical/gasses/co2dynamics.shtml
and here:
http://en.wikipedia.org/wiki/Carbon_dioxide

Just wanted to say big thanks to Jack A Lopez for the very detailed answer and follow up. It's a looong time overdue but I didn't realise anyone had responded. Apologies!

I'm looking for something practical. One, is it true that the cartridge here would inflate a Mae West? How big a balloon would it inflate? Would one of those 1-meter oblate ellipsoidal "Happy Birthday" balloons be limp? Explode? I find it a little hard to believe that one cartridge only expands to 6.1 liters. I did the calculations (4 * pi * r^3)/3, and came up with a sphere radius 11.3cm. That's not very big - about the size of a bowling ball. What am I missing here?

What I have in mind is one of those big balloons with a large predator's face printed on it, so that if there's a bear, you could quickly inflate this pocket thing and "brandish" it; it could scare away a bear if you hold it right and make enough noise, wouldn't you think? (I guess that if the cartridge has too much gas, a relief valve would work.)

Along those lines, what I had in mind was a tiny regulator, that would stop letting gas out when the balloon is inflated fully.

Hello,

This topic interests me. Did you get a solution with solenoid valves for CO2 cartridge ?

According to this site the pressure in a 12gram at room temperature is about 70bar. You will need some kind of regulator before your valve.