Paintball CO2 Valve Question

I purchased a CO2 fill station from a paintball supply place. It’s used to fill up the 9-20oz bottles used on the paintball guns from a bulk 20 or 50 pound CO2 tank.

To get a little learning in, I rented a 20 pound tank from the local welding supply place. It’s got a siphon tube (aka dip tube) and what looks like a standard CGA320 threaded valve on it.

The problem is that when I screw the fill station onto the bulk tank valve it doesn’t look like there’s any way for the things to work together.

I damn myself for not having pictures to present, but here’s a description of the two valves:

Fill station valve is basically a big brass nut that screws onto the bulk tank. Seated inside the nut is a big plastic o-ring and a metal tube that leads off to the filling apparatus. Idea is you screw it to the bulk tank, turn on the main valve of the bulk tank, CO2 flows.

The bulk tank has an interesting looking fitting on it. It’s a hunk of brass about 3/4" in diameter threaded on the outside (the nut on the fill station fits it perfectly) and it has a small (about 1/4" diameter) hole running down it (into the tank valve) that is threaded on the INSIDE:

  This end is where the fill station screws on.

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…and this end goes into the tank valve.

The dashed line represents the little threaded hole where gas flows from the tank.

The problem is that nothing on my fill station fits into that little threaded hole. Leaving the fill station out of it, I can turn the tank valve into the “Open” position and no gas comes out - makes sense, there’s evidently something that is supposed to go down that little threaded hole and depress something first. But my fill station doesn’t have it.

Does anyone know what I need to ask for at the welding shop to make this work? The fill station instructions mention “Tighten carbonic nut to male stem of fill cylinder”, I assume that the “male stem” is what the welding shop didn’t include.

I’m going to take the whole assembly into a local paintball store tomorrow but wondering if anyone knows the answer…

OK, here’s a page showing a similar setup:

The tank neck can be seen, painted blue. You can see the big brass carbonic nut attached to the tank valve (this fellow has it hooked to a regulator and uses it to make fizzy water but no matter).

And there’s a helpful line down the page:

“CO2 tanks and regulators use a unique flat nipple fitting (CGA 320, 0.825-14NGO-RH-EXT, flat nipple) and washer to connect to each other, instead of the usual inert-gas nipple (CGA 580, 0.965-14NGO-RH-INT, such as for argon, nitrogen, or helium). The flat nipple squeezes against the mating tank outlet, being compressed by a large captive nut, with a fiber or plastic washer in between the flat faces. You must firmly attach the regulator nut with a new washer to assure a leak-free fit.”

So perhaps my setup is fine - certainly appears to be a flat nipple fitting. I’ll make sure everything is snugged down properly and try it again.


Link to page previously mentioned…

Screwed everything together snugly, it all works EXCEPT that no gas flows from the bulk CO2 tank. Bummer.

Obviously not the hottest thread here but it’s compressed gas so I’d rather think out loud and perhaps avoid doing something dumb.

Checked around online and the CGA320 fittings are completely standard, the “flat nipple” fitting is absolutely normal. My best bet at this point is that the on/off handwheel of the bulk CO2 tank is just a little sticky and needs a good hard turn to actually open and allow gas to flow. I’m calling the welding supply place later to confirm this (if they say “It takes 1/8 turn and no more” then something is wrong, if they say “One full turn” then it’s just a little tight and I was being cautious).

If you hear a loud “BANG” call 911 :slight_smile:

Go about your business…