Air pistol air

DonDon · Post by **DonDon** » Wed Oct 15, 2008 11:54 am

Hello forum,

I bought a Daisy 747 about a month ago & have become hooked on it. I have been looking at the higher end guns & have read some articles about CO2 vs. air & I read something I would not have thought of living in Florida which was that there may not be any dive shops in some areas. So, I was wondering if an "air" gun can be run on compressed oxygen or some other gas that is readily available from a welding shop. Also are there different types of CO2 (I have used welders with CO2 but it was a gas, when filling CO2 guns it is a liquid). Are ther different types of tanks for the same gas with one releasing gas & the other liquid?

Thanks,
DonDon

David Levene · Post by **David Levene** » Wed Oct 15, 2008 12:14 pm

I believe, and please check before trying it, that you can use compressed nitrogen instead of air.

SRichieR · Post by **SRichieR** » Wed Oct 15, 2008 12:35 pm

For liquid CO2 you need a tank with a syphon tube (dip tube). The tube picks up the liquid from the bottom of the tank. Otherwise you'd have to turn the tank upside down. These are somewhat uncommon but are available from welding supply shops in my area. It's the same type of tank used for filling paint ball guns.

Industrial compressed air around here is typically 300 bar (over 4000 psi) and uses different fittings. Air guns are typically 200 bar (approx 3000 psi) which is typical of scuba tanks. Using a 200 bar scuba tank there aren't as many problems with fittings matching up and it is virtually impossible to overpressurize the gun's cylinder and create an unsafe situation. I have seen and used an industrial tank, however, a pressure regulator and various fittings had to be installed. I was always afraid someone might mess with the regulator setting and a 200 bar cylinder would get 300 bar.

Tycho · Post by **Tycho** » Wed Oct 15, 2008 12:53 pm

Airgun tanks should be tested for 50% overpressure, so a catastrophic failure shouldn't happen even in case of a 300 bar mistake. Or you buy a LP300 or Tesro, they use 300 bar. Furthermore, many "normal" air pistols can shoot 250 bar (Morini for sure, and SAM even lists it in the manual. Doesn't work in a Steyr LP5!!) so it might be interesting to be able to fill up to that in a controlled way.

spacepilot · Post by **spacepilot** » Wed Oct 15, 2008 1:02 pm

DonDon, I'm sure others will provide you with excellent advice. Just a piece of caution: I have no way of verifying what's said in this blog article, but after reading it, I wouldn't risk putting compressed oxygen into my gun.

Edit: found something else about filling airgun cylinder with compressed air. Looks like it's definitely a big no-no.

Oz · Post by Oz » Wed Oct 15, 2008 1:13 pm

Compressed Oxygen, maybe not... but it is an interesting question. What about another inert gas such as Argon? It is readily available at welding supply shops. Helium would also be another excellent inert gas option. This is again, readily available at a lot of different locations.

My though is that these gasses would be just fine, it’s simply the economics. Compressed atmospheric air is significantly less expensive than Argon or Helium.

LOL…. I’m thinking that the first elite shooter who wins a significant event while using Argon would create such a run. Half the shooters at the next major event would be hailing Argon as far superior to compressed air for one reason or another ;)

Oz

Fred Mannis · Post by **Fred Mannis** » Wed Oct 15, 2008 3:07 pm

Here is some basic info on using/filling compressed air pistols and CO2 pistols, courtesy of our host: http://www.pilkguns.com/scubasafety.shtml. http://www.pilkguns.com/co2.shtml

It really isn't worth messing around with anything other than a 200 bar SCBA compressed air tank. KISS principle. I have a 80 cu ft tank that I refill once or twice a year. No big deal even if you have to drive a bit.

DonDon · Post by **DonDon** » Wed Oct 15, 2008 4:12 pm

Hello everyone,

I forgot about the oil & oxygen. I thought of the nitrogen also & I think there was another I have used with mig welders but cannot remember, but did not know if the density was different enough to change velocity or anything. I have plenty of dive shops in my area but was curious about it since reading the thread about people farther inland in case I find myself going somewhere else if my job disappears.

I sure am glad someone remembered the oil, it has been a few years since I have been around torches & did not even think of it.

So what do people do in the desert or mountains?

Thanks,
DonDon

pgfaini · Post by **pgfaini** » Wed Oct 15, 2008 4:19 pm

Don, Are you living in a small town with a volunteer fire dept.? If so, they usually have means of filling their Scott Pac. tanks. My local VFD, has a "low pressure" pump that fills to 2000psi, and brings their "high pressure" 4000psi. tanks to a larger dept for filling. They've offered to fill my tanks, but not wanting to leave them, I use a dive shop.
Nitrogen is also excellent, but expensive. Our air is about 70% nitrogen.
Paul

Gwhite · Post by **Gwhite** » Wed Oct 15, 2008 5:28 pm

Why mess with tanks & hydrotesting & such at all? I just use a Hill hand pump. As long as I fill my cylinders AFTER I shoot, it works fine & gives me a good workout.

I used to have a large CO2 cylinder for a Walther CP2. Every five years, it needed hydrotesting, and I used to get it filled at a scientific gas supplier to make sure I was getting dry gas. That all adds up after a while. The pump will pay for itself in 15 years, and save me a lot of driving back & forth. At least with a SCUBA tank you can generally get it filled & tested a lot easier than CO2.

As an aside, a friend of mine got a CO2 tank for his Walther, but he bought it second hand from a soda fountain outfit. Turns out it had been run empty at some point & back filled with water. A $600 water pistol is a very sad sight.

RobStubbs · Post by **RobStubbs** » Thu Oct 16, 2008 1:58 am

Gwhite wrote:Why mess with tanks & hydrotesting & such at all? I just use a Hill hand pump. As long as I fill my cylinders AFTER I shoot, it works fine & gives me a good workout.

Because you want dry air in your guns, the pumps don't remove the moisture from air, which is why they need constant bleeding to remove the water. Over time that extra moisture will lead to corrosion.

Plus a scuba cylinder lasts 6 - 9 months and costs me a few pounds to refil (that's less than 5 US dollars).

Rob.

Tycho · Post by **Tycho** » Thu Oct 16, 2008 3:16 am

There was a rumour some years ago about Helium being used and giving better results (group size) than normal air... Nitrogen works fine, btw, I've seen that myself. And no problem with condensated water, either...

edster99 · Post by **edster99** » Thu Oct 16, 2008 10:48 am

Oxygen is almost the same desnity as air so in that respect fine. However, the danger is in the sudden flow of the gas over a restriction which causes frictional heating and if the item is flammable, away you go with a bang. So there is danger in filling the cylinder (adiabatic heating) and in shooting with it.

Conversely, anything inert - helium, argon, neon, nitrogen, will cause you no problem at all. The only issue might be with helium that it leaks out through seals. Nitrogen is 79% of air, hence has the same properties except inert. IF you can get it for free its probably about as ideal as it gets. Theres no real benefit if you have to pay...

I cant imagine any particular gas makes any difference to group size unless it happens to change the velocity to the 'sweet spot' for the barrel/pellet combination. Its only the total power and pressure profile that comes into it, and how different would they really be?

Use diving quality gas if possible - air is safe, nitrogen safer, helium safe (but expensive), oxygen totally dangerous - as these are all dry. You dont want corrosion in your mechanism, although the ally cylinders on most PCPs will be much less susceptible than the steel components internally.

Oxygen - no. Diving air - yes. Wet gas - no. Dry inert gas - yes. If in doubt - stick with precompressed, divers air. Dont pay over the odds for anything more than that.

cheers

Ed

ronpistolero · Post by **ronpistolero** » Thu Oct 16, 2008 6:47 pm

Apart from being expensive as a point of disadvantage, using helium gas would give you a difficult time shooting the way you're used to....imagine hearing strange sounding voices when they inhale the helium :-)

J.Hoes · Post by **J.Hoes** » Fri Oct 17, 2008 11:29 am

It would be interesting to check if operating an air weapon with "non-air" (not CO2) would make it a non-air weapon or fireweapon.

greetings Hans

Tycho · Post by **Tycho** » Fri Oct 17, 2008 12:32 pm

Well, using Oxygen would definitely make it a firearm...

J.Hoes · Post by **J.Hoes** » Fri Oct 17, 2008 3:25 pm

LOL, it would definitely make a firy arm, and change the legal status to scrap..

But seriously, if one fills an airpistol with non-air (except CO2) would that change its legal status? Apart from safety reasons, Dutch gun laws would allow it.

greetings Hans.

Gwhite · Post by **Gwhite** » Fri Oct 17, 2008 8:26 pm

RobStubbs wrote: Because you want dry air in your guns, the pumps don't remove the moisture from air, which is why they need constant bleeding to remove the water. Over time that extra moisture will lead to corrosion.

The Hill pump comes with a dessicant filter option. I also keep the humidity in my basement quite low (~40% tops) to avoid corrosion on my tools & guns.

Scuba air isn't totally dry either. If you want dry, a nitrogen tank would be best.

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Air pistol air

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