I have a full 20# tank and two empty 5#s. The recent thread on tank filling inspired me to ask question: how do I transfer Co2 from the large tank to the small tank and is there safety risk involved? I am assuming both tanks are syphon type. Thanks for looking!
How to transfer Co2 from large tank to small tank
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Do you know for a fact that your tanks are siphon tanks? If so, they wouldn't be any good for brewing, as the liquid would destroy your regulators.
There are Co2 fillers that you can buy, they basically have two CGA-320 fittings, one that has a valve, and the other usually attached to a high pressure hose.
With typical non-siphon tank, you would need to invert your larger tank to push liquid CO2 into the smaller tank, so having an upside down tank has its own challenges and safety issues.
The other issue that is unlikely to happen is an overfill, but you can weigh the tanks before and after filling to ensure that you haven't overfilled your tank. The reason why this is unlikely, is usually you need to freeze the receiving tank to get close to a full fill, and if you freeze it, you can also overfill. Overfill situations are really just scary when the burst disc breaks and releases all the CO2 at once into your room. If you weigh the tank before the fill (essentially double checking the tare weight), and you know the receiving tank is empty, when you weigh the tank again after filling, you will know exactly how much CO2 is in the tank.
Now, this is all assuming all your tanks are within their hydrotest date. If they are not, you really should bring them to get them tested.
If you don't chill your receiving tank, you will likely not get a full fill due to the equilibrium reached when the receiving tank starts to pressurize.
As always with pressures this high, be careful, do a lot more research, and if you then don't feel comfortable, bring it to the professionals to fill. Saving a few bucks is not worth getting hurt!
There are Co2 fillers that you can buy, they basically have two CGA-320 fittings, one that has a valve, and the other usually attached to a high pressure hose.
With typical non-siphon tank, you would need to invert your larger tank to push liquid CO2 into the smaller tank, so having an upside down tank has its own challenges and safety issues.
The other issue that is unlikely to happen is an overfill, but you can weigh the tanks before and after filling to ensure that you haven't overfilled your tank. The reason why this is unlikely, is usually you need to freeze the receiving tank to get close to a full fill, and if you freeze it, you can also overfill. Overfill situations are really just scary when the burst disc breaks and releases all the CO2 at once into your room. If you weigh the tank before the fill (essentially double checking the tare weight), and you know the receiving tank is empty, when you weigh the tank again after filling, you will know exactly how much CO2 is in the tank.
Now, this is all assuming all your tanks are within their hydrotest date. If they are not, you really should bring them to get them tested.
If you don't chill your receiving tank, you will likely not get a full fill due to the equilibrium reached when the receiving tank starts to pressurize.
As always with pressures this high, be careful, do a lot more research, and if you then don't feel comfortable, bring it to the professionals to fill. Saving a few bucks is not worth getting hurt!
Thank you so much for that prompt and thorough reply! Is there a way to determine what is and what isn't a siphon tank?
yoop89
Well-Known Member
Like gnef said if you have used the tanks for pushing beer at all then they are likely not siphon tanks. As the name implies, siphon tanks have a dip tube in them so they draw off the liquid co2 at the bottom of the tank. If you were to somehow hook up a regulator to one of these tanks and try to pressurize a keg with it the liquid co2 would destroy your regulator.
Have you used the 20# tank to push beer at all? Are these all just standard aluminum tanks?
EDIT: Out of curiosity I just did a quick search for a siphon tank and it appears you can in fact buy just a siphon tube on amazon for a standard 20# CO2 tank. Doesnt look like the valve is any different either.
Have you used the 20# tank to push beer at all? Are these all just standard aluminum tanks?
EDIT: Out of curiosity I just did a quick search for a siphon tank and it appears you can in fact buy just a siphon tube on amazon for a standard 20# CO2 tank. Doesnt look like the valve is any different either.
If I remember correctly (and this is always suspect!), most of the CGA 320 valves can be fit with a siphon tube, and ones that have a siphon, can have it removed.
Now, you should really have a professional do this for you, the tank valve is something you want to be able to trust completely considering these pressures.
If you do desire to have a large siphon tank, then make sure you only use it for filling, and never with a regulator attached. I personally don't think it is worth it to try to fill at home like this, as you tend to waste a good amount of co2, and it is a nuisance to get a full fill without a pump, plus you are then liable for anything that could potentially happen, and it can be dangerous!
So it sounds like you've used your tanks with regulators and did not destroy your regulator, so it does not seem like you have siphon tanks. If you bought your tanks from a welding supply shop, they would have made it exceptionally clear that you were buying a siphon tank, as it would not have been typical for them.
Stand the tank upright. Open the valve. If gas comes out then there is no siphon tube. If dry ice shoots out then it has a siphon tube. I fill smaller tanks by inverting my 20# tank. The receiving tank is always on a scale so that I can monitor the progress. It's always kind of scary if I think about it too much.
The bigger question is why? Why? And again, Why?
Get your 5# filled or swapped.
Or if the price per pound for 5# fills is too high, switch to using 20# tanks. Or 50# tanks.
I can't see how jumping through hoops to fill a few 5# at home offers much benefit. The potential risks involved juggling with high pressure gas don't outweigh a few bucks saved.
Get your 5# filled or swapped.
Or if the price per pound for 5# fills is too high, switch to using 20# tanks. Or 50# tanks.
I can't see how jumping through hoops to fill a few 5# at home offers much benefit. The potential risks involved juggling with high pressure gas don't outweigh a few bucks saved.
That! ^
Yup, that is exactly what I did. About a decade ago, I had at least a dozen CO2 tanks, ranging from 2.5# all the way through 50#, and it was honestly a pain to keep up with that range of tanks - keeping track of how much was left, if it was empty, if I had time to refill it, if it needed a hydrotest, etc.
So I decided to standardize on two tanks, two 50# tanks for stationary use in the beer room and walk-in, and five 20# tanks for portable use, and anytime I needed CO2 somewhere other than where my 50# tanks were.
I have since slightly changed my position on the 50# tanks - it took me 9 years to go through the first one that was just used for serving, so now I keep a 20# tank for serving at the walk-in, and use the 50# tanks for carbing and stationary use.
