CO2 cylinders not filling all the way.

[6string]

Hi,
I have a "new to me" Pardini K60. Great pistol. But, I'm having trouble getting a complete fill on the cylinders.
I have three of them. I also have two newly filled 5lb tanks. Nothing leaks.

No matter what, I can only get 12 grams in any of the three cylinders. I tried both my CO2 tanks and each of the three cylinders. I tried putting them in the fridge for an hour or so, tried putting them in the freezer, and tried room temperature. Same thing every time. I tried with the tanks upright and upside down. And, I tried just letting one sit attached with the valve open for a minute. They hold CO2 just fine: weigh them overnight, same weight (12 grams).
Is there some technique I'm overlooking?
The only common element is the fill adapter. Do they need special attention?
Thanks!

[David M]

CO2 are filled by weight with liquid CO2.
Firstly, is your CO@ supply a top gas feed tank or a liquid bottom feed tank.
Liquid feed tanks usually have a vertical stripe down the tank.
If you are using CO2 fire extingusher to fill you need to turn it upside down to feed liquid.
Bleed off you pistol tank (and/or cool in the fridge if not chilled when empty) and weigh the tank.
Attach to CO2 liquid feed tank and open the valve.
Fill tank ank shut valve.
Re-weigh tank, the difference is the weight of liquid.
Do not over fill, if over filled bleed off some liquid.
CO2 pistols work on the reed vapour pressure of CO2 converting liquid to gas.
So you need some gas space in the tank and the rest liquid.
Constant pressure is obtained as the liquid boils off until all liquid has been converted to gas.
Hope this helps.

[Gwhite]

The problem is pretty unusual if you are following David M's guidelines.

Possibilities:

1) The valves in the cylinders are tired. I've had issues with filling Tau-7 CO2 pistols after the O-ring in the fill valve got mashed over time & largely closed off the passageway.

2) For some reason the fill adapter isn't opening the cylinder valves completely. I suppose it's possible the pin that opens the cylinder valve is worn or damaged.

3) Some fill adapters have a filter in them. That may be clogged.

The fact that you can get some CO2 into the cylinders suggests that you are close, but something is not quite right. Remember that you are dealing with a liquid, and it may take some time to trickle through the hardware, especially if the valves aren't opening as well as they should.

[6string]

I'll try some of these ideas.
The strange thing is the consistency of the weight amongst three different cylinders filled with two different tanks! 12 grams, every time!
Yes, the fill adapter has what looks like a bundle of copper wires as a filter.

Thank you the kind consideration of your replies!

Jim

BTW: I used to CO2 pistols (Walther and FWB) about 20 yrs ago when my old club still ran matches.

[northpaw]

No matter what, I can only get 12 grams in any of the three cylinders.

Apparently, ther´s nothing wrong with your sylinders.

I tried with the tanks upright and upside down.

A tru sign of a CO2 tank that has ran out of liquid CO2. If you put your 3 sylinders in the fridge after filling 12 grams, then you may get another 12 grams of CO2 into your sylinders, for a total of 24 grams. Try this procedure and let us know.

[David M]

Test your CO2 supply tank for liquid (same test as a LPG bottle).
Use a kettle full of boiling water, and pour some down the outside of the tank.
Then feel the tank from the top down, the change of feel from warm to cool is
the level of liquid in the tank.

[6string]

Hi,
I'll try your suggestions and post the results.
The tare weight for the tanks is 7.4 lbs. They both weigh just over 12 lbs.
I was under the impression that 5 lbs of CO2 pressurized to fit in the tank causes the CO2 to liquify.
Is there such a thing as CO2 tanks for liquid vs gas? Is it just a question as to whether it has a syphon tube or not?

[David M]

The way a CO2 pistol works is that the liquid in the tankboils off to produce gas.
As the pressure is about the critical point, the pressure is approx. 80 bar.
When you shoot a shot the pressure drops a little, more liquid boils and the pressure increases.
This keeps going until all the liquid has boiled off, then the pressure drops.
All CO2 storage bottles are liquid, some are liquid delivery (drop tube), some are gas supply.

[6string]

Perfect description. Thank you for your generosity and patience in sharing your knowledge.
I should be home soonto try a few ideas.

Jim

[northpaw]

I was under the impression that 5 lbs of CO2 pressurized to fit in the tank causes the CO2 to liquify.

You are right, 5 lbs of CO2 means there is quite some liquid CO2 in the tank.

Is there such a thing as CO2 tanks for liquid vs gas? Is it just a question as to whether it has a syphon tube or not?

That could be the culprit: If you drain CO2 from a tank that has no riser tube, then you just drain gas, no liquid, if the tank is upright. Have you tried to fill from the tank put upside down? To fill a sylinder properly you have to drain liquid CO2 from the tank.

[6string]

Success!
Filling the cylinder with the tank upside down makes sense. But, my mistake was I was opening the valve then inverting the tank. By inverting the tank, then opening the valve, I got a perfect fill each time. One cylinder filled to exactly 52 gr CO2, the next to 48 gr. It hadn't occurred to me that by opening the valve first that the gas would fill the cylinder and not be displaced by the liquid.
By the way, I was so elated to get this figured out that I fired over 100 pellets and the remaining CO2 is still holding out strong!

Hopefully, this will help someone else out in the future.
Thanks again to everyone for their help and expertise.

Jim

[David M]

Now, be careful not to over fill, fill by weight only after cooling.
Also do not fill then leave in a hot car before shooting.
The pressure may increase too much that the hammer of
the pistol will not open the valve.
Happened a lot in the Australian summer, if it does, just bleed off
a little CO2, it will cool and lower the pressure.

[6string]

Thanks. If I understand correctly, 53 gr is the max fill weight.
By the way, one thing I forgot to mention above, I used the bleed valve to release all the gas before filling.

[Gwhite]

If you chilled it, there's no need to bleed it. That just wastes CO2. In an emergency, you can chill the cylinder by bleeding it, but a refrigerator works fine.

I'd start by making sure the filter in the fill adapter is clean. Try flushing it (backwards) with an aerosol solvent.

[Rover]

Now, be careful not to over fill, fill by weight only after cooling.
Also do not fill then leave in a hot car before shooting.
The pressure may increase too much that the hammer of
the pistol will not open the valve.
Happened a lot in the Australian summer, if it does, just bleed off
a little CO2, it will cool and lower the pressure.

Spot on! I've had the same experience while living in the Arizona desert.

Quick and dirty: put the cylinder in the freezer for only five minutes, then fill. Don't bother with weighing. You may not get uniform fills, but with CO2 you get so many shots it doesn't matter.

[David M]

Rover....CO2 also works well for chilling you beer.

[6string]

Thanks for yet more tips. I like to shoot both in my basement range and my outdoor range. With hot weather on the way, I'll heed the advice.

Funny thing you mentioned beer....
The girl I got the two CO2 tanks from used them in a kegorator. She had a box with parts in it and asked me if I wanted them.
"Sure! Thanks", I said. When I got home, I found a complete brand new beer keg rig for draft beer: hoses, regulators, tap & handle, keg valve, etc.
Well, I do some homebrewing myself, but have been bottling it up to now. Maybe I can get double duty out of the CO2?

Anyhow, not a bad deal for $25! (Did I mention the one CO2 tank was full, too?)

Jim

[Gwhite]

Be careful. CO2 tanks used for beverages can be back-filled with water if they aren't used properly. A friend of mine was one of the very first people in the US to get a Walther CP2, and he got a "great deal" on a CO2 tank that had been used for carbonated beverages. He ended up with the world's most expensive water pistol...

I think it's a problem in a system when you have two CO2 tanks in parallel for a quick switch-over. When one tank runs really low and they don't shut the valve off before they crank open the second one, water in the system gets pushed into the empty one.

[6string]

Hi,
I remember that story, and that there was a "beverage" component to it.
Probably best to keep any potential systems exclusive to one another!
Thanks,
Jim