Doing your own CO2 refills from a larger tank

Hi folks! First post on HBT; I hope this isn't a question that's been answered before, my search didn't turn up anything.

I've got a 5# and 20# for my homebrewing. I'm lucky enough to also work in a microbrewery, and there are always a bunch of tanks, 50# I think, circulating though here.

I figure there must me some device you can get to refill small tanks off a bigger one - just something to let you equalize the pressure between the two. Small tank swaps are expensive around here, it would be great if I could just tap the brewery's supply. Has anyone ever heard of such a thing?

Thanks!

Yes...
But when filling a CO2 tank you fill liquid not gas.
Most tanks are not syphon tube cylinders so you would need turn the 50lb tank upside down to get the liquid CO2.
A scale to make sure you do not overfill your tank.
Safety equipment, liquid CO2 is a freeze hazard.
High pressure hose and fittings.

I'd google and get more information and facts.

I used to work in the custom spraying and ag testing field. We would do 4' handheld sprayers with a 5lb CO2 backpack tank through a two liter bottle with the appropriate product mix to the boom. I did self fills all the time. Smooth is right about the siphon tube. A standard CO2 tank will not fill the liquid, never tried them upside down.

You would need a high pressure transfer hose. Hook the two together, open the small, empty tank, open the larger tank. Wait till the sound of transferring liquid stops. Close big tank. Close small tank. Just barely crack the fitting to release pressure (our hose had a pressure relief built in that you could crack open). Voila! A scale would be useful for making sure you dont overfill. I never used one, probably have hundreds of self fills under my belt.

Disclaimer: This is dangerous. You are dealing with a high pressure gas. Things can and will explode. The expanding gas causes temperatures well below zero.

I say go for it - the Darwin Awards are always looking for new candidates

xmacro said:

I say go for it - the Darwin Awards are always looking for new candidates

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Thanks for the vote of confidence, man. If I'm here asking for the opinion of folks with more experience, it's so that I hopefully stay out of the running.

ktm250 said:

A standard CO2 tank will not fill the liquid, never tried them upside down.

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Thanks for the input, ktm. I'm just not sure I understand - so you were using non-standard tanks? Or did I miss something?

There are two types of CO2 tanks that he is talking about here. A siphon tube tank has an inner tube connected to the valve that pulls the condensed liquid CO2 from the bottom of the tank, much like the dip tube on your keg pulls beer from the bottom. A standard CO2 tank does not have this tube, so when you open the valve you get the gas that is in the headspace of the cylinder.

From what I have read, it is possible to use a standard tank to fill by turning it upside down, or tilting enough so that liquid will flow out instead of gas. The hazards of such a practice are increased as dropping the tank on its top (the valve) will likely result in injury and certainly property damage, such as the tank rocketing through your roof.

If you can design some kind of ramp that would allow you to secure an inverted standard tank, I don't see much of a problem with flowing liquid CO2 through the valve, hi-pressure cryogenic tubing (or just direct metal fittings), and the valve on the donor tank. As someone said, best to weight the cylinder to make sure you don't overfill.

Anyone see a problem with this approach? This coming from the guy who has not actually tried this...

I think paintball guys do this. I have a friend that uses a 20 oz paintball tank for serving, and he fills it and force carbs with the larger 20lb tank. He mentioned having the right part to do the transfer, but that is all I know.

I have refilled my paintball tanks from a bigger normal tank that was hung upside down.
you need a scale for the tank that is filling so you dont overfill it.
some high pressure needle valves,the ones I had where rated at 6000#.
all fittings and nipples use sced 80 forged fittings with high pressure rateings.
overfilled one tank and the bust disk blew off while driving and scared the crap out of me.

You need a high-pressure hose with tank connectors at both ends and a SOLID stand to hold the 50 lb tank upside-down so you can also access the valve. And a scale, because an overfilled tank can blow the safety disk with even a small change in temperature. With those, it's safe enough.

I used one of these of the right size to hold my tank up.
http://www.grainger.com/Grainger/ANVIL-Riser-Clamp-4HYK2?Pid=search

Merlmabase said:

Thanks for the vote of confidence, man. If I'm here asking for the opinion of folks with more experience, it's so that I hopefully stay out of the running.

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Let's put it this way - there's a reason you need to be licensed to refill CO2 tanks, just like there's a reason those tanks are made of steel.

luminum

crash1292 said:

overfilled one tank and the bust disk blew off while driving and scared the crap out of me.

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Your lucky. I used to work in a paintball shop. Have a nice triangular scar on my left hand where the burst disk blew in my hand and I got a rather nasty case of frostbite. That tank was filled to correct weight, a few hours later I was carrying my tank out of the shop and it blew.

Any gas under enough pressure to be turned to a liquid is not stuff to mess around with. Really anything under a lot of pressure should never be messed with.

xmacro said:

I say go for it - the Darwin Awards are always looking for new candidates

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I'm probably due one. Not only do I refill CO2 bottles from my inverted 20# tank but I also refill 1# propane cylinders from a 20# tank in pretty much the same manner.

Or get a tank with a siphon tube.
http://www.amazon.com/dp/B0088P2JW6/?tag=skimlinks_replacement-20
I would say go for it. You need a license to do a lot of stuff, but with proper research and equipment I’d say you’ll be safe.

As a couple other have pointed out, paintball guys do this all the time. I do the same as they do for my portable kegerator. They hang a 20# upside down on a little stand and fill a 12 or 20 ounce from it.

I gave about $30 for the fill rig from ebay. It's the proper connector on both ends, 2 valves, and a T. Very simple setup.

Connect the two tanks, open the transfer valve, dump some liquid in the receiving tank, close the transfer valve, open the dump valve and blow the liquid, close the dump valve, open transfer valve and watch the scale.

Easy peezy. I just hold my 20# in the left arm and work the valve with the right arm. One day, I'll make a stand.

Oh - so you don't have to ask: The initial ounce or two of liquid that you move into the receiving tank, then dump is to chill the receiving tank. If you don't have it really cold, the CO2 can boil when it hits the tank and cause the pressure to go up thereby stopping anymore liquid from transferring.

Another thing to keep in mind is you'll be filling tank to tank not pump filling. Both tanks should hold the same pressure making it impossible to over fill the smaller tank.

Beer_Eugenics said:

Another thing to keep in mind is you'll be filling tank to tank not pump filling. Both tanks should hold the same pressure making it impossible to over fill the smaller tank.

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That is not true.

If the procedure outlined by Huff360 is followed, overfill is easily accomplished.

Use a scale!

Thanks for all the excellent advice! To get into the nitty-gritty, just for fun:

My understanding is that the state of a compound is mostly (entirely?) a function of temperature and pressure. So I get the trick of doing a fast blow-off to chill your destination tank.

Not that I need or intend to try this, but could you also just equalize the head pressure with both tanks upright, then let off a bit of pressure from the destination tank? From that point, perhaps you could transfer the liquid from your inverted source tank, and it would stop itself once you hit equilibrium in the destination tank.

Assuming that works, with a little careful experimentation, you could probably figure out the exact difference in head pressure you need to get the right amount of liquid transfer.

Just speculatin'.

P-J said:

That is not true.

If the procedure outlined by Huff360 is followed, overfill is easily accomplished.

Use a scale!

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If this is true what is the point of pump filling?
The few times I had my tank tank filled it was no where near five pounds.
I would think the two tanks would equalize in pressure.
Also huff360 was talking about a paintball canister not a five pounder, they might have diffrent psi ratings.

Beer_Eugenics said:

If this is true what is the point of pump filling?

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You pump to keep from having to chill or vent the receive tank.

Beer_Eugenics said:

The few times I had my tank tank filled it was no where near five pounds.

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Assuming you had a 5# tank, they cheated you. Next time ask them to give you what you paid for.

Beer_Eugenics said:

I would think the two tanks would equalize in pressure.

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They will given enough time. Ideally, the receive tank will still be a lower pressure when it reaches 100% capacity. You then shut the valve and once the two tanks reach the same temp, the pressure will pretty much equalize. If you chill the receive tank far enough, it is possible to fill it well past 100% of capacity with liquid.

Beer_Eugenics said:

Also huff360 was talking about a paintball canister not a five pounder, they might have diffrent psi ratings.

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CO2 is not stored as a gas. It is stored as a liquid. Pressure in a properly filled tank has absolutely nothing to do with the quantity of liquid in the tank. It depends only on the temperature of the tank. The tanks are all rated the same.

Good to know. I had a problem with getting a full fill at the place I was going and they told me that’s because they tank fill and if I wanted all five pounds that I would have to leave it so they could pump fill it. Also when I did have it tank filled the guy just filled a little purged a little then filled again until there was no more noise and did not use a scale. Guess this is why I was only getting 2.5 to 3 pounds when they tank filled. Thanks for the info.

Beer_Eugenics said:

Good to know. I had a problem with getting a full fill at the place I was going and they told me that’s because they tank fill and if I wanted all five pounds that I would have to leave it so they could pump fill it. Also when I did have it tank filled the guy just filled a little purged a little then filled again until there was no more noise and did not use a scale. Guess this is why I was only getting 2.5 to 3 pounds when they tank filled. Thanks for the info.

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Absolutely right. If he had purged enough to make your tank ice cold, then it would have taken more. Next time you go, put your tank in an ice chest full of ice for a while. Take it out of the ice and hand it to him to fill. : )

Without really really chilling it, there is no way he will get a complete fill. If I were a commercial shop, I would put it on a scale regardless. No point in even risking the liability.

I pull a vacuum on my 5# tank when I transfer +1 for using a scale never had to get the tank cold but always shut down valve just before 5# safe then sorry can always fill again. 5# is only used when I take kegs out somewhere then most of the time I take my 3 gallon tanks.

Here is what you seek. Stay thirsty my friends, Cheers.
http://powertank.com/products/sfID1/37/productID/419

Also can not wait till my presidential brew is ready for downing.