airbrushing - co2 vs nitrogen

Ok - still new bar here and havent built any rockets or plastic models (another old hobby not getting back into atm) for years until a few months ago and am already tired of rattle cans. It doesnt help I currently live in an apt so dont have lots of room for overspray. In the past I had a paasche vl (unfortunatly still dont have it) and used a 20lb co2 tank and will be getting another airbrush shortly (not sure which - liked the vl a lot so probably just get that). I liked the tank as it is quiet and the start up cost is about the same as a good compressor and you dont need a moisture trap. Doing some research I see that nitrogen is also used. Anyone have any experience or pros/cons on one vs the other or is it 6 of one, half a dozen of the other?

Off the top of my head I can think of these pros/cons

co2 pro - "lower pressure" in tank since it is liquid boiling off vs high pressure tank
co2 con - co2 in a small area can be fatal

nitrogen pro - air is mostly nitrogen so less problems in a small area
nitrogen con - high pressure gas leak/rupture could be more energetic than the same in co2 tank - both not good either

Any other thoughts?

Thanks

Steve

Steve....

Unfortunately I don't have an answer of CO2 vs nitrogen. But I also live in an apartment and use an airbrush on rockets. I used a few little CO2 cans when I first got it but I hated how they always froze up and never lasted too long. I bought a used airbrush compressor off of ebay several years ago and haven't looked back since. I bought a moisture trap at my local Lowe's store and it works like a charm.

good - sounds like airbrush will help the small space thing - I was not talking about those small overpriced cans of air that might paint 2 lpr rockets and freeze up etc - I was looking at large gas canisters - the size they use at bars/resturants for carbonation and other uses - they come in a few sizes, 2.5 lb -too small, 5lb, small but great for portability, 20lb - the most common i think, and larger - probably get a 20lb unless i find a 5 lber for next to nothing - these require a regulator and are quite nice to use and last quite a while

SteveF said:

Ok - still new bar here and havent built any rockets or plastic models (another old hobby not getting back into atm) for years until a few months ago and am already tired of rattle cans. It doesnt help I currently live in an apt so dont have lots of room for overspray. In the past I had a paasche vl (unfortunatly still dont have it) and used a 20lb co2 tank and will be getting another airbrush shortly (not sure which - liked the vl a lot so probably just get that). I liked the tank as it is quiet and the start up cost is about the same as a good compressor and you dont need a moisture trap. Doing some research I see that nitrogen is also used. Anyone have any experience or pros/cons on one vs the other or is it 6 of one, half a dozen of the other?

Off the top of my head I can think of these pros/cons

co2 pro - "lower pressure" in tank since it is liquid boiling off vs high pressure tank
co2 con - co2 in a small area can be fatal

nitrogen pro - air is mostly nitrogen so less problems in a small area
nitrogen con - high pressure gas leak/rupture could be more energetic than the same in co2 tank - both not good either

Any other thoughts?

Thanks

Steve

Click to expand...

Nitrogen in a confined space can be fatal too-- ANY GAS that displaces too much oxygen can be fatal! Two technicians died back in the 80's during the space shuttle program, when they entered the engine compartment of the shuttle for maintenance after a launch scrub-- the engine compartment of the shuttle is flooded with nitrogen gas before liftoff to displace all the oxygen, to help minimize the risk of fire from any propellant leaks. They entered before the nitrogen had been flushed out with fresh air, collapsed unconscious and asphyxiated before anyone realized it. Not good to play around with.

I take it you have a good regulator... you'll be getting your gas at a welding supply?? TSC and other 'farm stores' now have 'welding gas' cylinders in a lot of the stores, and can set you up with a good exchange program with little or no demurrage. Oxy-acetylene Company (AOC) and other welding gas suppliers can too, but it just depends on what's handiest for you.

I'd tend to think that the liquid CO2 would be a lot more 'dense' than gaseous compressed nitrogen would be. Airbrushes don't use a LOT of volume, but seems to me that the N2 tank would deplete faster than the CO2 tank merely on a density standpoint. I wouldn't worry about the cylinder rupturing-- if you're getting it from a reputable dealer, the cylinders have to be DOT inspected, and recertified every so often. Besides, either way, if the cylinder DID rupture, you're gonna be halfway to the next county before you know what hit you anyway...

Might want to check your rental agreement on stuff like that, anyway-- some places might not allow high pressure cylinders in the residential units... even knocking a cylinder over and busting the head valve off will usually send them through a cinder block wall, and sheetrock seperating your apartment from the neighbors is like tissue paper in that case... neighbors might not like having a cylinder shoot through the kitchen wall while they're eating their wheaties some morning...

Just something to think about... OL JR

I also didn't mention that I only use water-based acrylic paint.

FWIW, I have a regular air compressor in the garage. From that I fill a portable air cylinder that's sold to carry around to fill tires, etc. On my workbench I run it through a regulator and then to my airbrush. It works fine, I don't worry about leaks displacing the air in my basement (or forgetting to turn things all the way off) and when it's empty, I just walk to the garage and fill it.

When I was in college, we lost a professor to an accident similar to what was described. he had a welding unit in the basement and, although it had been there for years, the acetylene leaked from somewhere and displaced al the air in the basement. CO2 is also heavier than air and can pool in still air. Be careful.

luke strawwalker said:

Nitrogen in a confined space can be fatal too-- ANY GAS that displaces too much oxygen can be fatal! Two technicians died back in the 80's during the space shuttle program, when they entered the engine compartment of the shuttle for maintenance after a launch scrub-- the engine compartment of the shuttle is flooded with nitrogen gas before liftoff to displace all the oxygen, to help minimize the risk of fire from any propellant leaks. They entered before the nitrogen had been flushed out with fresh air, collapsed unconscious and asphyxiated before anyone realized it. Not good to play around with.

Click to expand...

And the most scary part about N2 asphyxiation is you won't realize it. Because it's not toxic to you, your body has no discomfort mechanism to warn you... Unlike the physical discomfort you can get with CO2 poisoning.

N

Peartree said:

FWIW, I have a regular air compressor in the garage. From that I fill a portable air cylinder that's sold to carry around to fill tires, etc. On my workbench I run it through a regulator and then to my airbrush. It works fine, I don't worry about leaks displacing the air in my basement (or forgetting to turn things all the way off) and when it's empty, I just walk to the garage and fill it.

When I was in college, we lost a professor to an accident similar to what was described. he had a welding unit in the basement and, although it had been there for years, the acetylene leaked from somewhere and displaced al the air in the basement. CO2 is also heavier than air and can pool in still air. Be careful.

Click to expand...

OH MAN!!! Thankfully there wasn't an explosion I take it!?? Sorry that your professor lost his life, but an air/acetylene explosion would probably take out half a block!

When I was in mechanic's school, we were warned about working on freon filled air conditioning and refrigeration units next to a shop pit in the next bay... this was just when refrigerant recapture machines were just coming out and a lot of mechanics were still just 'venting' the stuff by taking a fitting loose before replacing whatever part needed fixing. More than one mechanic has been killed working in a shop pit beside a guy fixing an AC/reefer in the next bay by vented freon pooling on the floor and sinking into the pit, displacing all the air and asphyxiating them.

Nobody's EVER been able to explain how heavier than air freon ends up 60 miles high eating up the ozone layer... :roll::roll::roll:

Later! OL JR

Ahh the K bottle torpedo. I've been in safety training sessions for work where they show the Mythbusters clip of a K bottle going through cinder block wall

Space program also has had more accidents than just what luke strawwalker points out, beside other N2 incidents, there were several with He purges, fortunately when you pass out from He exposure you fall out of the O2 lean area. At which point you come to and they send you down the launch pad to have a smoke and walk it off. (at least that was the SOP in the 1960's learned that in the same training as above)

Steve, the complex will probably frown on the gas bottle, even if it's not in the renters agreement or lease they usually keep the power to change those things on any whim they have. So it might be OK at first but then they find out and say were changing the rules.

thanks all - kinda knew most of that. Have handled the 20lb tank of co2 in the past so am aware of the care they need. Still undecided so will probably just go with a 10 or 20 lb co2 tank since that is what I have experience with and the 10lb would still last me quite a while

ok - got a paasche vl kit today so will be getting a tank in the next few days (still could go compressor, but probably not) - any last thoughts on the co2 vs n2? or still 6 of one, half a dozen of the other

Well, I think probably most folks have put in the :2: and probably haven't changed much in their assessments... Personally I still would prefer a compressor or air tank over compressed gases, especially in enclosed areas, and particularly over CO2 which could be a safety hazard, but that's just me.

Let us know how it works out for ya though... Maybe I'm just over-cautious... OL JR

If you were real cheap you can go get an old tire intertube and get a regulator/moisture trap attachment to it. I have an Iwata Hp-c and I would spring for a small studio compressor though if you were seriously going to use your airbrush.

Bender222 said:

If you were real cheap you can go get an old tire intertube and get a regulator/moisture trap attachment to it. I have an Iwata Hp-c and I would spring for a small studio compressor though if you were seriously going to use your airbrush.

Click to expand...

Innertubes don't hold much pressure unless they're inside the tire You can use your spare tire (assuming you have a full-size spare, not those tiny donut things most cars come with now) for a "high pressure" (well, 35 PSI or so) air supply on the cheap. Most hardware/auto stores sell portable air tanks of about 4-5 gallons in size that can be aired up to 100-130 PSI at the local service station too, for less that $20 or so. An innertube by itself can only hold maybe 3-5 PSI (guessing but AT MOST) without a tire holding it together-- otherwise they'll stretch til they burst...

You can even use a tire to air up another tire in a pinch-- I had a low rear tire on the tractor (they only air up to about 10-20 PSI but they're 30 inch diameter tires, so use a LOT of air) and ran out of air in the portable tank, so once the tank was down to about 5-10 PSI, I went to the trailer and 'aired up' the full trailer tires, which actually let the air flow from the 36 PSI trailer tires flow BACKWARD through the hose into the air tank, bringing it up to about 20 PSI before the trailer tire lowered to 20 PSI and the air pressures equalized and quit flowing. Then I did the same to the rear trailer tire (tandem axles) and got the pressure in the tank up to like 30 PSI before the air pressure equalized in the tire and quit flowing. That 30 PSI was enough to bring the tractor tire up to 15 PSI or so, which was fully inflated, so I could get back to work without having to go to town and get another tank of air. When I went to town for lunch I stopped by the station and aired up my trailer tires back to 36 PSI and put 110 PSI in my air tank in case I needed it later in the day. Works like a champ and saved a lot of time! OL JR