Filling CO2

[Glovebox Operator]

I realized the other day I could fill some of my old tanks because I have a nearly full 20#(?) cylinder with my welding stuff. I got a fill station and only dared to put a little pressure in an old 4oz tank as a test run. Is there anything I need to know before actually filling tanks for real? I know I need a scale and I won't be filling tanks that are out of hydro.

[Chappy]

Does your fill tank have a siphon tube?

[Glovebox Operator]

I have no idea. I know nothing about this tank other than a friend bought it at a yard sale and i got it from him. How would I figure that out?

[Trbo323]

Does your fill tank have a siphon tube?

Yeah that's probably the most important thing, a welding tank is set up for gas coming out. You need liquid to fill the tank.

The easiest way around it is to just flip the welding tank upside down but you'll need a decent way to mount it so you can use your hands to fill your paintball tank, unless you have like 4 hands

If you are just filling to mess around at home I wouldn't worry about a scale. Just pop open the valves and wait until everything equalizes pressure. Without venting the PB tank to chill the contents it's almost impossible to overfill when you just let the pressures equalize. If you are looking to get the PB tank properly full then yes you'll need a scale and you'll be blowing off some CO2 in order to chill the PB tank. One way to help with this and not have to blow off as much CO2 is to chill the PB tank in a freezer for at least a few hours before filling. You'll likely still have to blow off a bit but not as much this way

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[Trbo323]

Post a picture of the tank

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[Glovebox Operator]

This thing is ooooold. Not at old as the 100# propane tank i got from a neighbor with a 1948 date stamp.

[Glovebox Operator]

Pretty sure it doesn't have a siphon tube. I'll probably make a cradle to hold it upside down till it's used up and then trade it in for a proper one.

[Glovebox Operator]

Good point about freezing the tanks first. And I didn't figure it could overpressurize the tanks since they operate at liquid co2 pressure too, but it's good to know from from people that have played around with them.

[Trbo323]

This thing is ooooold. Not at old as the 100# propane tank i got from a neighbor with a 1948 date stamp.

Lol, I'm a propane delivery driver. I think the oldest tank I've filled is 1950 if I remember right. As long as it's in decent shape the age really doesn't matter

Good point about freezing the tanks first. And I didn't figure it could overpressurize the tanks since they operate at liquid co2 pressure too, but it's good to know from from people that have played around with them.

The problem is if it gets 100% full of liquid the pressure in the tank skyrockets. That can happen after you fill and the temperature stabilizes to it's surrounding, the liquid expands and takes up more space.

That said, and like I said before, if you just pop the valves open and let it equalize I've never had a situation where that alone has completely filled a tank to its weight capacity

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[Drcemento]

It’s still pretty hard to overfill a frozen tank more than an ounce or two, but yes, excercise caution and get a fish scale. Every siphon tank I’ve ever gotten was clearly marked with a giant “DT” for dip tube spray painted on the side. Our local gas supplier actually adds the tubes themselves. I’ve re-valves a bunch of my nicer black Annoed oz tanks from back in the day and put them on my loaner snipers phantoms and SL’s for outlaw play. So many More shots with Co2 and my soda streams always have gas.

[Hp_lovecraft]

In the old days it was pretty common to see fields using non-siphon tanks because it was cheaper. Paintball Boston built large wooden cradles to hold them upside. Paintball Passion suspended them upside with chains, which was terrifying! But any good welding supply will carry simply metal cradles, and valve guards, or whatever. Just be safe.

Way way back in the 80s, we didn't use a fill station. We just had an adapter for CO2 tanks to fit directly on the bulk tank. We used a cheap walmart fish scale. Maybe $5. We would weight tank, screw in to bulk tank, fill a couple oz, unscrew, chill, rescrew, fill completely, unscrew, weight.... then drain as needed. On rental tanks, we would often market on them the weight.

In the old days, burst discs were 1800psi, so proper filling was HUGE. Blowing discs were a nightmare. but most tanks made after the mid 90s were switched to 3000psi discs, so blowing the discs because almost unheard of.... though its the reason that most fields started underfilling tanks.

But, still weight them. Overfilling causes overpressure..... and having a burst disc let go while driving a car is about the most exciting that I never want to experience again. Get a cheap fish scale.