TargetTalk

Ok, I'll show just how little I know. I was talking with my local welding supplier about having CO2 onsite for shooters and he asked if I needed liquid or gas.

HELP!

Jack -
I have had the same experience with other gas companies. Air Guns that use CO2 need liguid not gas. To get liquid, the supply tank needs either a dip or siphon tube or be turned upside down. It works similar to a garden pressure sprayer. I would recommend the dip tube. John

A cylinder of CO2 gas at normal temperatures would not hold much gas. CO2 has the property of becoming a liquid at comparatively low pressure - the outcome being that a 'full' cylinder of pressurised CO2 will be mainly liquid, with a bit of CO2 gas at the top (all at the same pressure). This is the beauty of CO2, for each shot the pistol/rifle gets a charge of gas at a constant pressure. After firing a shot, the pressure goes down a bit, some liquid vaporises off to restore the pressure of the gas, and this will happen every time until the liquid component is expended.

To draw off the liquid from the bulk tank when refilling the firearm reservoir, a tube to draw liquid from the bottom of the bulk tank is needed - usually indicated by a black stripe down the side of the bulk tank. Alternatively, a normal tank without a draw tube can be inverted but this can do bad things to the tank's valve seals, and having $$$ of CO2 vent off into the atmosphere is not a good financial practice.

Without the draw tube, in theory, if the firearm reservoir is kept colder than the bulk tank and they are connected, EVENTUALLY the firearm reservoir will condense enough CO2 to fill. In practice, we use both techniques:
- cool the firearm reservoir (stick it in the freezer for 5 - 10 minutes), and
- use a bulk tank with a draw tube.

Overfilling the firearm reservoir can be a problem - the firearm draws liquid CO2 instead of gas until enough of the excess is used up - so a set of scales to check that you get the 'optimum' charge of CO2. The tare and net weights will normally be stamped on each reservoir somewhere.
Too much CO2 will cause problems, too little might not see you through a match.

Hope this helps,
Spencer C

Thanks for the education.

The welding guy mentioned the dip tube.

Jack ...

Also think of how many shooters you are filling off the tank.

I have a 20lb CO2 tank with a dip tube. My 4-H club shoots 3 times per week and I usually use 9-12 Daisy 888 cylinders per session. So I'm filling anywhere between 27-35 cylinders per week.


I end up refilling the bulk 20 lb tank about once every 8 weeks now.
(Note ... the dip tubes do not go all the way to the bottom of the tanks so you will probably not get to about 2lbs of CO2 ... so you really have a 18lb tank)

My 20 lb tank cost me about $100 with the first fill. I pay anywhere between $17.50 and $22.50 to fill this tank. (I keep the same tank and just have them re-fill it)

If you go with an 80 lb tank, you will go lots longer, but it's too heavy/large to really throw in the back seat and take to get filled ... they will usually come and swap it out for a full one ... I think the folks here in NM pay about $60-$80 to fill one of these big puppies.

I like the 20lb tank as I can easily cart it to matches.

i thought i replied earlier but it didn't appear, musta been computer problems.

Take a poll, I think you will find that the overwhelming majority of air gun shooters use compressed air!

you will need numerous scuba tanks and (3 or 4 at OTC were barely adequate for the 3X-air match) a local dive shop where you can get them filled some afternoon during a multi-day match.

I don't recall seeing anyone filling off the CO2 tanks at OTC.

Poole

Bill,

I notice the same at major shoots around the world. At the really elite level it is unusual to see any CO2 pistols or rifles.
For several years, most of the shoots at the Sydney Olympic range used CO2 out of my home supply tank - in 1999 that was quite a few shooters each competition; by the 2002 World Cup, hardly any. Even at a 'local' mature age competition last month there were only a handful of us using CO2.

However, there are thousands of CO2 rifles and pistols still out there that are quite capable of shooting a world record in the right hands.


Spencer C

27-35 cylinders a week seems like a lot of shooting. How many shots per cylinder are you getting. A cylinder should be good for at least 200 shots per fill. Daisy claims 300 I think.

Jack:

Install a compressor on-site. Buy 3 scuba tanks. Use (and enforce) the "cascade" system where competitors fill off off the lowest tank first, then the most recently topped-off tank. Rotate the fresh tank in, and lowest tank out, when the pressure of the "top" tank gets below 2500.

Or buy a buttload of scuba tanks and do the same thing- just keep the "full" tanks under lock and key.

Or you will end up with 10 tanks all under 2500 on the first day of competition . . . (and a lot of whiny competitors).

Steve Swartz