Converting Scuba Tank to CO2

RRADFORD9ER

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Joined
Dec 3, 2006
Location
Asheville
I just picked up an old Scuba tank for free! I'd like to make it into a co2 system...is that possible? From what I understand the Scuba tank can handle over 3000 psi, while CO2 tanks are only subjected to around 800 psi.
The first thing I noticed was the valve is different. Can a CO2 valve be fitted on the Scuba tank?
 
What will you be using it for? To power tools or lockers?

Just keep it like it is and have a scuba shop fill it. Its like $10 to fill it. It will have comressed air, not oxygen, up to 3200 psi.

IIRC, a standard valve will fit in there, but I can't remember. Just find out what the threads are and get it matched up with a regulator you want.
 
I know the hydro is out of date, thats part of the reason I got it for free. Can any dive/welding shop hydro test it?

Main use is for airing back up tires. I don't have any air tools yet, but I'd like to get an impact wrench, for quick trail repairs.
 
Yhea most places will test it out.
You really don't need guages on your regulator. The primary guage lets you know how full the tank is and the secondary allows you to control output pressure. You can get a fixed regulator(most are set at 150psi) and run air tools safely. Just use an old fish scale to weigh the tank empty and then again when full. Whenever you think you are runing out weigh the tank and compare it to your original #'s.
CO2 has constant pressure and will remain the same whether the tank is 100% full or 1/8 full. My tank will put out 150psi constantly till it is empty.

Buy a regulator from Wilson balloons or The Source etc, get some superbraid high pressure coiled hose and a fire extinguisher bracket for the tank. You can build the whole setup like PowerTank for under $75.00 since you have a tank already.

I can post pics of my set up if you like.

Here's a few more links:
http://http://www.stu-offroad.com/re.../co2/co2-1.htm
http://http://www.williamsballoons.c...n_dioxide.html
http://http://www.4x4rockshop.com/sc...idCategory=214
 
Took the scuba tank by the welding shop today to see what I could do with it. Guy there said there was no way to convert it to use CO2. I called the 2 scuba shops within an hour of my house, both of them seemed to think it was possible if the tank passed hydro. I guess I'll keep looking for a CO2 tank...cause I'm not paying $50 to get the tank hydro'd if I can't even use it for CO2.
 
High Pressure Air would work, but from what I've read it wouldn't provide as much usable volume as a similar sized CO2 unit. I'd rather spend $50 and get a CO2 tank than to pay the same amount of $ to get the SCUBA tank hydro'd and have a less functional air source.

Edit: The WJ's rocking 2 Save Tellico Stickers!
 
I see that you're not in the Raleigh area...but if you just want to ask someone that should know the answers...give these guys a call. All the Scuba shops in the area send their tanks to get hyro'd here and I've taken a CO2 tank to get hydro'd & filled here.

Pye Barker Fire & Safety Inc
www.pyebarkerfiresafety.com

832 Purser Dr # 101
Raleigh, NC 27603
(919) 779-4010
 
RRADFORD9ER said:
High Pressure Air would work, but from what I've read it wouldn't provide as much usable volume as a similar sized CO2 unit. I'd rather spend $50 and get a CO2 tank than to pay the same amount of $ to get the SCUBA tank hydro'd and have a less functional air source.

Edit: The WJ's rocking 2 Save Tellico Stickers!
Click to expand...

Ah, ha, so if I got this right,CO2 compresses more than air? makes sense
 
rockcity said:
I don't see why the amount of use would be any significant difference between CO2 and air...
Click to expand...

I think what he's saying is, that you can get more total volume of CO2 (more "quantity", if you will) in that same confined space than if you used regular air. Since, ounce for ounce, eitehr will push the device/do the job equally, you will get more use out of a tank "full" of CO2 than one of air.

Is this correct?
In the end, I guess it comes down to mass. What is the total mass of air you can fit in a tank, verses CO2. Since CO2 is "pure" and becoems a liquid at lower pressure, it seems to make sense that you'd be able to sqeeze more in there.

But I'm just talking out of my ass..
 
IIRC thats true. But its the other way around under high pressure CO2 becomes a liquid
"CO2 gas is 1.5 times as heavy as air, thus if released to the air it will concentrate at low elevations. Carbon dioxide will form "dry ice" at -78.5ºC (-109.3º F). One kg of dry ice has the cooling capacity of 2 kg of ordinary ice. Gaseous or liquid carbon dioxide, stored under pressure, will form dry ice through an auto-refrigeration process if rapidly depressured.
Carbon dioxide is commercially available as high pressure cylinder gas, relatively low pressure (about 300 psig or 20 barg) refrigerated liquid, or as dry ice. Large quantities are produced and consumed at industrial sites making fertilizers, plastics and rubber."
 
mass should have zero to do with the amout that is in there, we're talking about volume.

1 Cubic foot of gold has a greater mass than 1 cubic foot of steel, but has identical volume...
 
CO2 gas is stored compressed in liquid form. When you go to use the CO2 it "boils off" turning back into a gas. I don't know the exact expansion rate of CO2, but it is pretty high. Another factor is that compressed CO2 will remain at a constant pressure no matter if the tank is completely full or 1/8th full. That means you will get optimum pressure output for the entire tank of CO2. HPA would only offer optimum pressure output while it was almost completely full. A third factor for wanting CO2 is that when stored in the tank, the gas only exerts around 800 psi. A full HPA tank is closer to 3000 psi. I'd rather not have the extra 2200 psi in the jeep if something were to go wrong.
 
Tetanus said:
I see that you're not in the Raleigh area...but if you just want to ask someone that should know the answers...give these guys a call. All the Scuba shops in the area send their tanks to get hyro'd here and I've taken a CO2 tank to get hydro'd & filled here.
Pye Barker Fire & Safety Inc
www.pyebarkerfiresafety.com
832 Purser Dr # 101
Raleigh, NC 27603
(919) 779-4010
Click to expand...

We've got one of those in Hendersonville. I'll check them out. Thanks
 
rockcity said:
mass should have zero to do with the amout that is in there, we're talking about volume.
1 Cubic foot of gold has a greater mass than 1 cubic foot of steel, but has identical volume...
Click to expand...

I'm sorry, but that is not correct.
You cannot measure gas by volume. Volume is a measurement of how much space an item take up. A gas will expand to fill the entire space of a container, therefore you cannoy measure how much space it takes up. X amount of CO2 could fil leither a 2' tall bottle or 4' tall.
So what you are left with measuring is mass... how much is in a fixed space. As the mass goes up (cramming more into your bottle), so does the pressure.
This means that really teh ebst way to know how much gas you have inside a bottle is to weigh it, then subtract off teh weight of the tank. The remaining represents the weight of the gas. unfortunately, many gasses (e.g. Argon) are so light that one cannot really tell by hand what the difference is. Since CO2 is a liquid, it's fairly heavy and you can tell.

[straight to hell]
imagine a car full of mexicans. No matter how big the car is, there wsill always be enough riding for it to be packed full.
[/straight to hell]
 
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