CO2 Tank Filling Station

I currently have 2 5# steel CO2 tanks. I use one for beer transfers and the other in my keezer. I don't have the option of using a large tank except if I used a large tank at say 20# or 50# to fill my two smaller tanks. Ideally I would like to have a large tank filled and save money. Once the large tank is filled I could refill my small tanks at my convenience. I figure at 15# a fill it would pay itself off relatively quickly. The problem is I don't know how to fill a tank and secondly I don't know where to buy anything but a setup to fill paintball tanks.

I don't know if this is something I would need
http://www.chicompany.net/index.php?main_page=product_info&cPath=20_312&products_id=776

I have found these paintball tank refill stations but they don't really help
http://www.opentip.com/Sporting-Goods/Co-Tanks-Cylinder-Refill-Kit-p-1250516.html

we use a (i think 50#) tank to refill our CO2 tanks at our research station. not that it's hard to do, but for some reason the pressure difference in the 5/10 # tanks isn't enough for them to completely fill. and then when the 50# tank starts to run low, there isn't enough pressure difference to use all that gas that's in there. in order to do it, you just need a transfer hose with a gauge and bleeder valves on it so you don't blow yourself up.

First, your large tank needs to have a dip tube in it, and a special assembly to pass liquid CO2 to the receiving tank. In other words, you can't use a regular CO2 tank like we do for serving. It's a different animal internally.

(I've never filled a CO2 tank...)
But I've heard that in order to get 5# of CO2 into a 5# tank, you have to charge it with some CO2, and let that all out to basically "freeze" the receiving bottle. At the lower temperature they will take a 5# charge.

The other thing you'd need is a good scale, so you know how much is in there...

I'd be really curious if you find the parts to do this, if it's worth it, and how you pulled it off. It's a cool idea if you can get a good price on a bottom-feeding CO2 bottle

Without a diptube in the tank you have to turn the tank upside down. I fill paintball tanks from my 20# beer tank. Lots of filling stations (required connectors, valves and hoses) for sale on ebay.

The main issue is having a hose assembly (whip) that will screw on to each tank valve. It also needs a bleed valve so that you can depressurize the assembly after both tank valves are closed.

unless you have a compressor, you'll need to chill the empty tank to get a complete fill, otherwise too much liquid CO2 will vaporize and equalize pressures between the two tanks before it's full.

USE A SCALE!!! It's easy to over-fill a chilled tank, and pressures can skyrocket when a tank is even slightly over-filled, so ALWAYS FILL BY WEIGHT

Your fill tank needs to be inverted, or have a dip tube, so you're moving liquid CO2 instead of gas.

A paintball station would be a good start, but you'd need to replace the pin connector with a CGA-320 connector to fill a 5lb tank

Chilling the tanks should be no problem. One of them is already within my keezer at all times and if not cold enough I could always throw it in the freezer or flush it with CO2 to chill it down quickly.
I didn't realize you needed a tank with a diptube to transfer liquid CO2. I guess turning it upside down COULD work although I have no idea if this is safe even though people do if for paintball. Obviously there is the risk of it falling but is it also safe if the tank is secured well?

It sounds like I would need a large 20-50# tank which I could scrounge up somewhere with or without a siphon tube. Additionally I would need the transfer valves etc and a hanging scale or something similar to get the tank weight during the process.

Just as a rough estimate it seems I could get this setup for under $100. With each fill costing say $20 (overestimate) for a 20# tank. It currently costs me now $15 per fill for a 5# tank. With these numbers it would pay itself off after ten fills of the small 5# tanks. Not a bad payoff period with overestimated numbers to begin with. I'll have to see what I can find around ebay and craigslist.

You don't need a hanging scale.

If your grain scale has the capacity you can use that.

If it's digital, all you would have to do is empty the tank fully, zero the scale, and start filling.

I've been considering doing this for my portable 20oz tank. I already have a spare 20lbs tank and talked to the guy that I buy my co2 from about getting a dip tube.

Most places that swap out tanks will interchange diptube and non-diptube tanks. When You get a refill just ask for one. Add a $25 paintball refill setup and the correct stem for your tank and you're ready to go.

If you have a non-diptube tank you can safely flip it over and tie/strap it to a table leg or whatever. Anything that will protect the valve is good enough. Wear gloves when running the valves, they tend to get really cold.

http://forum.moatipaintball.com/index.php?showtopic=75531

bad coffee said:

Most places that swap out tanks will interchange diptube and non-diptube tanks. When You get a refill just ask for one. Add a $25 paintball refill setup and the correct stem for your tank and you're ready to go.

If you have a non-diptube tank you can safely flip it over and tie/strap it to a table leg or whatever. Anything that will protect the valve is good enough. Wear gloves when running the valves, they tend to get really cold.

http://forum.moatipaintball.com/index.php?showtopic=75531

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Thanks for the link. Really the only hurdle I see is finding tranfer setup that will thread onto a 5# CO tank. EVERYTHING I find is for a paintball tank which is nice but not helpful. Other than this I can find a large CO2 tank and flip it and a scale and be on my way to CO2 freedom.

Anyone have suggestions on where to find a CO2 transfer setup to work with a CO tank? Even an adapter to go from a paintball setup to our tanks....

You might be able to email someone on ebay to build you one with the correct fittings.
Right now they all have one fitting for CO2 tank and one end for Paintball.

You could also buy the correct fittings and swap it over yourself.

B

bad coffee said:

You might be able to email someone on ebay to build you one with the correct fittings.
Right now they all have one fitting for CO2 tank and one end for Paintball.

You could also buy the correct fittings and swap it over yourself.

B

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I simply don't know what fittings to order to do it myself. Ideally I would buy something already assembled to be sure my idiotic mistakes don't end up killing me.

Seems to me that you could piece together the fittings from a couple of used regulators.

Looking at the paintball refill setups they sell I can't get a good view of the fittings at the end where the tank would attach. I'm unsure if I could swap out fittings to make it work for a CO2 tank. I'll have to try to find a good picture of one.

The one badcoffee linked to looks like a 1/4" MPT fitting at the end and then the attachment for the paintball tank.

The paintball fill station lines are 1/8" MPT. All you would need to do is change out the paintball tank adapter to a CGA 320 adapter.
Click the link for the correct adapter to convert the fill station that bad coffee referenced for use in filling standard co² tanks.

HTH

Sweet action. So all in all I'm looking at ~$75 dollars in material plus the cost of the bulk tank and a new scale which I need anyways for weighing grain. I guess the next step would be find either a siphon or siphonless bulk tank on craigslist or another distributor near me. I'll keep the thread updated on my findings.

If you get a standard co² tank that is empty, it is simple to add a diptube inside the tank. Open the tank valve (to be sure there is no pressure inside) and then remove the valve stem. (The valve has straight threads on it and uses a 'face seal' gasket. NO teflon tape!) The inside port on the bottom of the valve is threaded (If I remember right - it is 3/8" FPT). Simply buy a 3/8" MPT x 3/8" compression fitting and place it on the valve stem. Then cut a length of 3/8" copper tubing long enough to reach the bottom of the tank when in place and install it in the compression fitting. Put it all back together and you are good to go. BTW, standard plumbing fittings are suitable for doing this as they will have the same pressure inside and outside the fitting.

Be sure to boldly label the tank as having a diptube. When you have it filled the first time, let them know that it must be purged before filling.

Hope this helps.

So I found a listing for a 50# tank with a siphon tube and it comes with a filling adapter. It's listed for $75 and the hydro expires in 2012. Oh and it's half full as well. Seems like a good deal to me. But the question I have is if there is a siphon tube can you use it for standard applications. In other words can I stick a regulator on it and push beer with it if I really want to? I would think the answer is yes but I'm not 100% on this.

no, you'd have to flip the tank upside down.

A non-diptube tank, the liquid is at the bottom, and the gas CO2 comes out the valve at the top. As the gas leaves, the liquid CO2 turns to gas to fill the empty space.

A diptube tank, the liquid is at the bottom, and there is a spear in the tank (the diptube) that goes to the bottom of the tank. When you open the valve, the pressure of the warm gas above the liquid pushes down on the liquid and forces LIQUID CO2 out the valve.

If you flip a dip tube tank over, the spear is at the 'top' and only gaseous CO2 can go out the valve at the 'bottom' of the tank.

I'd flip a 5, 10 or even 20 pound tank, but not a 50.

B

bad coffee said:

no, you'd have to flip the tank upside down.

A non-diptube tank, the liquid is at the bottom, and the gas CO2 comes out the valve at the top. As the gas leaves, the liquid CO2 turns to gas to fill the empty space.

A diptube tank, the liquid is at the bottom, and there is a spear in the tank (the diptube) that goes to the bottom of the tank. When you open the valve, the pressure of the warm gas above the liquid pushes down on the liquid and forces LIQUID CO2 out the valve.

If you flip a dip tube tank over, the spear is at the 'top' and only gaseous CO2 can go out the valve at the 'bottom' of the tank.

I'd flip a 5, 10 or even 20 pound tank, but not a 50.

B

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Gotcha. That makes sense and thanks for the logic and reasoning. I'm thinking $75 for that size of a tank that is with a current test date, half ful and comes with a filling station is a awesome deal. I'm going to try and call the guy tomorrow and see if it's still available. I figure to fill it once every two years and fill my 5# tanks at my leisure would be convenient and much cheaper quickly.