Refills from a bulk CO2 tank question

[Joe58]

I'm wondering if I could get an estimate for the number of refills a guy can expect to get from a bulk CO2 tank to their air pistol cylinders.

Say, a 10lb tank, and refilling an empty cylinder each time. I know there are a few factors that may effect the total number, but a rough guess would be good to know for a starting point.

I'm going to begin looking for a tank, maybe a paintball tank? dunno, and am trying to figure out what is a good size for home use without being ridiculous. Shouldn't need to lug it around with me.

And what I gathered from reading, I need a tank with a syphon so I don't have to use it upside down.

Thanks for the help. I usually need all the help I can get. :)

Joe

[Rover]

Get a 20lb. tank with a siphon. Without siphon, 10lb.

You'll get many more fills with CO2 than with air; so many you needn't concern yourself. They'll swap tanks at a welding supply for you, but the siphon may be a problem.

[Joe58]

Thanks Rover, good to hear.

Storing it upside down shouldn't be too big a deal, I was just thinking of convenience is all. I can probably cobble together some sort of holder to keep it in place.

And I'm sure I'll get the stink eye from the boss when she sees this tank stored in the utility room. I'm pretty used to that though. ;)

I read too that some of those tank places will just get into a swap program with you when you bring in your empty one, they'll exchange it for a full one.

Kinda like you can do with your grills propane tank.

Appreciated! Looking forward to trying a CO2 pistol as compared to my two SSP's. It'd be handy if in a pinch you could screw on a disposable type one like you can with a CO2 Crosman or Daisy.

Joe

[joel]

I also seem to remember something about putting the cylinder in the refrigerator a few hours before filling. That way, you can likely get more CO2 into it.

Joel

[Marc Orvin]

Yes, putting the cylinder in a freezer can help to get more liquid into the cylinder. However, you need gas to make your pistol work. You can overdo it with the freezing thing. CO2 cylinders should have a weight on them that you need to pay attention to in order to not overfill. If you overfill, you will get liquid CO2 pouring out the end of your muzzle for a few shots until you finally get to where there is gas in the cylinder.

This happened to my son when he was shooting a CO2 rifle.

[Joe58]

Correct. The manual says the weight of the cylinder as far as what it should be. I've read use the freezer, or just in the fridge is good enough. But I'll need to weigh before and after fill. I can use a bleeder screw to let some co2 out of the cylinder should I overfill. I'm sure until I get the hang of just how long a fill takes, I'll need to do that.

[Rover]

Correct. The manual says the weight of the cylinder as far as what it should be. I've read use the freezer, or just in the fridge is good enough. But I'll need to weigh before and after fill. I can use a bleeder screw to let some co2 out of the cylinder should I overfill. I'm sure until I get the hang of just how long a fill takes, I'll need to do that.

Forget all that. Put the cylinder in the freezer for five minutes, then fill and put on your gun. It's full when it stops filling ( a few seconds).

You must turn the fill tank upside down (you're dealing with a liquid) unless you have a siphon.

[Misny]

I've had CO2 and PCP. It is less hassle for me to get a scuba tank filled than it was a CO2 tank. The guns shoot equally well, but CO2 is temperature sensitive to outside air temperature and you should weigh your cylinders so as not to overfill them. You can cool the cylinders by bleeding off CO2 instead of putting them in a freezer. The only advantage to CO2 is that the guns are less expensive.

[saran]

Look for a 4 lbs tank. Easy to carry and to turn upside down when filling the cylinders.

Each of my C20's cylinders carry 53 grams of liquid CO2. To fill them up:

1. Chill the empty cylinder in the freezer for 10 minutes.

2. Attach it to the proper adapter in the tank (each gun maker has its own specific thread dimensions.)

3. Turn the tank upside down and open the valve. Be careful to point the cylinder to a wall, away from people. CO2 gear rarely fails but whent it does, it is spectacurlarly nasty.

4. Wait for 10 seconds, close the valve and detach the cylinder. A little bit of gas may escape at this point.

5. Weight the filled cylinder. FWBs full size pistol cylinders weight about 269 grams, so the full ones should weight 322. Bleed any extra CO2 with the supplied tool.

Remember:

Always chill the cylinder in advance. It heats up when filling and it may lead to a premature pressure equalization, preventing a full charge.

Always fill the empty cylinder. Any remaining liquid leads to a pressurized gas content and it may prevent any additional liquid to pour into the cylinder.

Be sure not to exceed the rated capacity. It ensures thst enough gas is in the cylinder regardless of ambient temperature (i.e., in the rated working temperatures.) If the cylinder is full of liquid, which is not compressible, it will certainly fail with any temperature increase.

A 4lbs/2Kg tank shall suffice for about 35 cylinder fills. For FWB pistols each one lasts about 300 shots.

[Joe58]

Thanks so much for the great tips. All stuff I need to know. I haven't started to track down a tank yet but that's my next step.

I did have a question about new cylinders. Will any FWB cylinder fit? And in the cylinder itself, is there a difference between a CO2 cylinder and a PCP one. Other than I know the PCP ones have the fill gauge on the front.

I really have the feeling that if I start messing with this CO2 pistol rather than sticking with my trusty Izzy and 65, it could end up getting expensive. :)

[machinist mike]

I don't know about FWB cylinders, but my Steyr LP-5/50 has different threads on the CO2 cylinders and the PCP cylinders. I certainly would not want to plug in a 200 bar PCP cylinder into a relatively low pressure CO2 system, so I quess the different threads are understandable. Be safe.