N rather than CO2 for OBA

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I'm not sure if this is the right place for this but...I was talking to a welding supply guy about refilling CO2 bottles and talked about OBA and CO2. He said he wouldn't use CO2 because of the fluctuation of CO2 with temperature variations. According to him, N would be better. The pressure of N and CO2 is about the same. Any thoughts on this?
 
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C02 is widely used as a oba source .. i have ran a power tank for alot of years in all sorts of temps and have never had a issue, i have had all sorts of OBA compressors and feel the C02 is the most versitale air source out there.. this weekend i was able to carry my tank out to my parts rig and run a impact pulling parts.. cost of a refill isnt bad and they last a long time, ya just cant be fillin all your buddies tires all the time..
n=nitrogen? i have never heard of anyone using this as a OBA source
 
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I tried that once. The nitrogen has a lot less volume than CO2 when expanded from liquid to gas. It basically runs out faster. Not worth it IMHO.
 
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The pressure of most Nitrogen tanks is about 2200psi and the CO2 is about 750-800psi. So you might need a new regulator or at least a new POL fitting.
 
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The fluctuation of CO2 with temp is not enough to cause concern. N is much more expensive. N stores are much higher pressures. N expands seven times when it is released from the tank, CO2 expands 40 times. This has been discussed many times here... use CO2... there is no gain from N and there are several drawbacks.

All the cool kids who think their cars are formula one racers use N to impress all the other cool kids. In the real world, real people with real cards will never seen any gains that they can possibly detect.



As an additional benefit, you can use your CO2 tank with your mig welder when your welding tank runs dry on a Sunday night and the gas supplier is not open. ;)

Or use it with your ready welder on the trail instead of using shielded wire.


Mark...
 
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AND...good for....

The fluctuation of CO2 with temp is not enough to cause concern. N is much more expensive. N stores are much higher pressures. N expands seven times when it is released from the tank, CO2 expands 40 times. This has been discussed many times here... use CO2... there is no gain from N and there are several drawbacks.

All the cool kids who think their cars are formula one racers use N to impress all the other cool kids. In the real world, real people with real cards will never seen any gains that they can possibly detect.



As an additional benefit, you can use your CO2 tank with your mig welder when your welding tank runs dry on a Sunday night and the gas supplier is not open. ;)

Or use it with your ready welder on the trail instead of using shielded wire.


Mark...


....and you can hook up your homebrew kegs so the tap flows nicely. ;)
 
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Nitrogen isn't much more money to fill. About the same for me in Az. Not that its a big deal but with c02 f every 17 degrees in temperature change has a 1 psi pressure change. If your only concern ever is to fill tires then c02 is a good way to go.

I like nitrogen because I ride dirt bikes and have air shocks on my sand rail which both require nitrogen. Its very convenient to have nitrogen around and be able to do everything.
 
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I don't remember where I heard it first. But in discussion with my welding gas supplier he agreed with the numbers.

CO2 undergoes a phase change. It is liquid at the 900psi it is stored at. So it expands a lot as it changes to gas. N is stored as a pressurized gas. So it does not have the same expansion when released to atmospheric pressure.


Mark...
 
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Mark W and CardinalFJ60 hit in on the head....you can weld and drink beer with C02...
F&%^ Nitrogen for OBA (although you can pour a nice stout with it!)
 
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Not to knock the guy or you, but I believe that information may be incorrect.

Gases follow specific laws, they expand as fast as they are released, and while some may expand at different rates, in the end they all will expand to fill any space they are in.

For example: ((P1*V1)/T1)=((P2*V2)/T2)

The difference in expansion rates does not really apply to this situation, due to the fact that the gases would be simply transferred into tires or air tools not the atmosphere.

Given the fact that the Nitrogen gas is stored at much higher pressures, there is substantially more potential energy within the tank, which in turn would mean more time to run tools or fill tires. Thus allowing longer times between refills.
 
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I am more than willing to allow that I may be wrong. I am just repeating what i have been told by others who know more about it than I do.

But I think you are overlooking the fact that CO2 is stored aas a liquid and N is stored as a gas.

??????


Mark...
 

Mace

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Not to knock the guy or you, but I believe that information may be incorrect.

Gases follow specific laws, they expand as fast as they are released, and while some may expand at different rates, in the end they all will expand to fill any space they are in.

For example: ((P1*V1)/T1)=((P2*V2)/T2)

The difference in expansion rates does not really apply to this situation, due to the fact that the gases would be simply transferred into tires or air tools not the atmosphere.

Given the fact that the Nitrogen gas is stored at much higher pressures, there is substantially more potential energy within the tank, which in turn would mean more time to run tools or fill tires. Thus allowing longer times between refills.

That's a nice answer and technically correct, however you are mistaken.
Mark hit the nail on the head, a phase change from a gas to a liquid is the difference.

Pressure is basically irrelevant. Because of the phase change (which your calculation does not take into account) a CO2 tank has approximately 3 times as much "volume" at lower pressures (40 lbs ish) than N2 does. Meaning, for the same size tank, Co2 can fill 3 times as many tires as a N2 tank can.

Your calculation is correct, however it is not applicable to this comparison.
 
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I totally forgot about that, the liquid to gas expansion ratio of CO2 is really high, If I remember correctly its around 500:1 or something.

In that case CO2 is much better, if N was stored as a liquid though it would be better. Its expansion ratio is higher.
 
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Not sure on all the math but from my paintball days.... 68ci nitrogen tank @3000psi=-900 shots, 20 oz co2=900 shots . at 4500 psi it went up to about 1200 shots for the same size tank.
I think I remember around 850psi at 70 degrees for 20 oz of co2.

So basically a 20oz co2 tank is give or take 4 ci 40ci. So a 40ci co2 tank at 850 psi will give 900 shots, the same as a 68ci nitrogen tank at 3000psi or a 48ci nitrogen tank at 4500 psi.
So in a strange way of looking at this it seems co2 as a liquid and at the same pressure and size would hold 3-4 times the volume. co2 is really measured in weight though.
 
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Well, just use liquid nitrogen, then!

(now THAT will give you a nice cold frosty beverage...)

t
 
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As I recall, the expansion ratio of CO2 is something like 3000%. In other words, a given volume of liquid, for example one cubic inch, will expand into 3,000 cubic inches of gas/vapor. I didn't know the degree at which temp would/may effect CO2. I'm going to use CO2. Liquid N is fun to play with but I don't want my tires or air tools to freeze.
 

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