Filling anti siphon C02 tanks

[Drcemento]

Recently rehabbed some old 12oz tanks with new valves and did a couple with anti siphon tubes - I cant seem to fill any of the anti siphon ones. is there some trick i'm missing? got the tubes from paintball gateway - followed the directions - the other re-valved ones fill fine.

I start to fill them and Co2 and it sounds good for a second before Co2 starts leaking out around the valve connection.

[Trbo323]

You're going to hate how simple this is

Flip them upside down when filling so the valve is down. That way theAS tube end is up

Remember, you are putting a liquid into that tank

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[Drcemento]

Thanks Trbo I'll give that a shot. Was able to get one filled by stuffing it in the freezer for a half hour - not always an option though.

[Fubarius]

Ok, I don't know precisely what you're doing when you're trying to fill your tanks, so I'm just going to go step by step. Half of it you'll probably go "well yeah, duh" but this is also for anyone else who stumbles upon this thread, so lets get started.

First, the anti-syphon tube MUST be bent. A simple straight tube does, well, nothing. The picture below should make it obvious why. Screw valve into the gun it's going on, bend tube upwards, install tank to valve. If the gun it's being install on has an angled down tank you'll want to bend the tube so the end is closer to the valve. Once the valve it torqued down good and tight mark the tank or valve with some paint so you know which way is up if you go to use it on a different gun. You should be able to unscrew a tank from the gun's asa about a half turn or so and still have ti seal to position the tube in the proper orientation.


Ok, now to filling. Step one, empty tank. It must be fully empty before you can begin filling.
Step two, weigh the empty tank. Don't have a scale? GET ONE. Not optional. Ideally one you can zero out after you hang the tank from it or set the tank on it. Usually a button labeled Tare.
Step three, using fill station put some CO2 in until it stops. It will only take an once or two to begin with. This is normal.
Step four, quickly drain out what you just put in. This will chill the tank. When you're filling you are equalizing the pressure between the bulk tank and the tank being filled. CO2 pressure is dependent on temperature. So you need the tank being filled to be colder than the bulk tank.
Step five, put more CO2 in the tank. It should take more than the first time.
Step six, if it didn't reach the desired weight of CO2, quickly drain out a little (an ounce or two) to re-chill the tank and try to fill again. Repeat as necessary.

It is very, very easy to get more than the rated weight of CO2 into a tank this way, which will cause the pressure in the tank to skyrocket when it gets back up to pressure. Hence the scale not being optional. Having a burst disk on a tank blow when you're holding it, or when it's in your gear bag, or in your car, is NOT fun.