Filling a 5 lb. co2 tank

I am currently waiting to receive my new kegging system that comes with a 5 lb co2 tank. I have a big 50 lb co2 tank that i fill paintball tanks with (9 - 20 oz tanks) this is a siphon tank so i cant directly use it with the regulator. Has anyone ever used these to fill a 5 lb co2 tank themselves? I just didnt know about filling such a big tank. I called around and its going to cost me $20 to fill the 5 lb tank. It only cost me $25 to exchange the 50 lb tank.

I would be interested in the answers that come up on this. I have 20# Co2 cylinders, and I'm having issues with the local gas place filling them. Apparently the cyliders that are stamped as belonging to CCE (Coke), they are unable to legally fill them. I do have one that I can get filled.
I was wondering what valving I would need in order to fill my 5# tank, and possible transfer as much as possible to one of my other 20# cylinders, then take back the one I can get filled, and get it refilled, and get my other three 20# tanks filled. Then I will be set for quite some time, on Co2.

in the research I do, we use 5# and 2.5# CO2 tanks to spray out our chemical treatments and we refill them from a 50# tank all the time. the only problem we run into is that when the 50# tank gets low, there isn't enough pressure to fully fill the 5# tanks, but you can still get some in there. and if you're filling your 50# tank occasionally anyway, I don't see that becoming much of a problem for you.

i know this probably isn't kosher, but I've heard of people using bondo to fill in those CCE stamps and repainting the CO2 tank so they don't have to deal with the 'legality' issues.

I'd like to revive this old thread, because this is exactly what I'd like to do. What fittings do I need. I already have a regular paintball fill station. I am guessing I will have to take off the paintball adapter (end of steel braid hose is 1/4" right hand threads). I am trying to find an adapter from cga320 threads to get to the 1/4" rh threads, but no dice. If anyone has experience, please give me a hand. Thanks.

ewibolo

You can fill from a tank with a diptube to another tank. Without a pump you will not get a full fill. I fill from a 50 to 5's often and as the bigger tank empties you will notice the 5# getting filled less and less like this: 4.8, 4.7, 4.6....

Get a high pressure hose rated 2500plus PSI to err on the high side and have a shop crimp in 1/4" females on both ends. Teflon tape a cga 320 stem RH and nut on both sides. I use a ball valve in the middle of the assembly to purge when done for safety.

Thanks, that's what I was looking for! I didn't know the nipple with RH threads existed. I thought they were only LH, so I was looking for some sort of coupling converter or something.
I'll post with the results when I successfully perform the refill from the larger tank.

Thanks again!

I guess the question would be, is the end of your existing hose 1/4" flare connection, or 1/4" NPT connection? If it is 1/4" NPT, you should be able to screw it onto a CGA 320 nipple, otherwise you will need a matching 1/4" flare to 1/4" NPT adapter to go between the hose and nut/nipple. The nut/nipple should cost less then $10 from a welding supply, and they can probably supply the adapter also, if not, a hydraulic supply co should have a pressure rated adapter, same goes for the mentioned ball valve if you choose to use it, as the ones at your local hardware stores are not going to be rated for CO2 tank pressures.

android said:

in the research I do, we use 5# and 2.5# CO2 tanks to spray out our chemical treatments and we refill them from a 50# tank all the time. the only problem we run into is that when the 50# tank gets low, there isn't enough pressure to fully fill the 5# tanks, but you can still get some in there. and if you're filling your 50# tank occasionally anyway, I don't see that becoming much of a problem for you.

i know this probably isn't kosher, but I've heard of people using bondo to fill in those CCE stamps and repainting the CO2 tank so they don't have to deal with the 'legality' issues.

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Put the 5lb'r in the freezer before filling, that will help.

You can't possibly overfill when transferring, correct?

JRems said:

You can't possibly overfill when transferring, correct?

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From my personal experience, that is not a concern, as the gas pressure in the tank will equalize before you finish transferring the liquid, which also means, you will not get a full 5lbs in a 5lb tank when filling from a larger tank. I can usually get about ~3lbs in my 5lb tank when filling from a 20lb siphon tank.

Curiosity strikes: if you are filling a non-siphon tank from a siphon tank, I would think if you bleed the head-space in the receiving tank you should be able to fill it right to the top, even with minimal pressure in the siphon tank.

What am I missing?

Cheers!

Yep, that would work, and it is how propane tanks are filled with liquid, well at least those without opd valves. The trick here is that liquid CO2 converts to gas very quickly, equalizing the tank pressures, and standard tanks do not have a pressure vent valve on them, minus of course the pressure relief valve. I would think that a ball valve inline with the fill hose would just vent off gas/liquid going through the line, and not from the receiving tank. Keeping the receiving tank as cold as possible will drop the pressure at which the co2 gas turns back into liquid, which is why chilling the receiving tank and using a warm fill tank(higher pressure) allows more liquid to transfer, but is still not going to give you full tank of co2.