Got Nitrogen?

[kman]

Simply put, because of the molecular properties of pure or almost pure nitrogen by itself vs. the toxic soup we regularly inflate a tire with, and using the coefficient n-1 to extrapolate the varied and extreme conditions of driving, you arrive at a mean value that approximates zero variability given any range of temperature change vs. the other stuff. Can I be any clearer?

[Ridley]

Originally Posted by kman

Simply put, because of the molecular properties of pure or almost pure nitrogen by itself vs. the toxic soup we regularly inflate a tire with, and using the coefficient n-1 to extrapolate the varied and extreme conditions of driving, you arrive at a mean value that approximates zero variability given any range of temperature change vs. the other stuff. Can I be any clearer?

Clear, but still bull****. There is absolutely no perceivable difference between the expansion, contraction, pressure change, etc, for use in tires between pure N2 and DRY air. Period. Doesn't matter what it's used for, racing, aircraft, whatever, still no difference. The only difference is that the pure N2 is DRY. Water vapor is the ONLY thing that makes any difference, and in street vehicle applications, it's negligable regardless. So, the bottom line is, N2 is a SCAM.

[kman]

Originally Posted by Ridley

Clear, but still bull****. There is absolutely no perceivable difference between the expansion, contraction, pressure change, etc, for use in tires between pure N2 and DRY air. Period. Doesn't matter what it's used for, racing, aircraft, whatever, still no difference. The only difference is that the pure N2 is DRY. Water vapor is the ONLY thing that makes any difference, and in street vehicle applications, it's negligable regardless. So, the bottom line is, N2 is a SCAM.

show me the math that supports it and i'll believe it.

[Ridley]

np gimme a sec

[Ridley]

[p+a(n2/v2)](V-nb)=nRT

V is the total volume
a is a measure of the attraction between the particles
b is the volume enclosed within a mole of the particles b = nAb',
n is the number of moles,
R is the gas constant

And using the established van der waals constants of:


% composition of air
N2=1.39 78.084%
02=1.36 20.947%
Ar=1.34 .934%
co2=3.59 .033%

You can see that at normal temperature fluctuations seen in tires, "air" and pure nitrogen will result in pressure variations of less than 1%. That would be the equivalent of ~1/2 psi at 50 psi

However, if you add a significant percentage of water vapor... with a van der waals constant of 5.46, you could see fluctuations of up to 5-7%, which is still absolutly irrelevant in a street car, but may have a slight disadvantage in a racing application where extreme temperature fluctuations in the tire occur and minute pressure variations have adverse handling effects.

SO, I'll reiterate.......Nitrogen is a scam. Most comercial compressors, have efficient air "dryers", so h2o vapor is not an issue. Now, if you have a hillbilly deluxe air compressor that has a tank full of water cause it's never been drained............N2 would be a good investment

The 20$ or so spent on the nitrogen scam, would be much better spent on an oil change

[CoeCEO]

"Thanks to its larger molecules, nitrogen stays confined within the tire longer, and helps maintain tire pressure because it diffuses at a rate about 30 to 40 percent slower than oxygen."

Found it here: http://www.theautochannel.com/news/2...25/105870.html

This may answer questions: http://www.getnitrogen.org/pdf/print...%20Article.pdf

Or this article: http://www.getnitrogen.org/pdf/print...nician-feb.pdf

All of these say Nitrogen molecules are larger.... I guess Nuke is the only one doing the math correctly?

Oh well, I did it and it was free.

[Ridley]

Originally Posted by CoeCEO

"Thanks to its larger molecules, nitrogen stays confined within the tire longer, and helps maintain tire pressure because it diffuses at a rate about 30 to 40 percent slower than oxygen."

Found it here: http://www.theautochannel.com/news/2...25/105870.html

This may answer questions: http://www.getnitrogen.org/pdf/print...%20Article.pdf

Or this article: http://www.getnitrogen.org/pdf/print...nician-feb.pdf

All of these say Nitrogen molecules are larger.... I guess Nuke is the only one doing the math correctly?

Oh well, I did it and it was free.

They are wrong. Nitrogen and oxygen are both diatomic molecules. Oxygen is actually the larger of the two and diffuses slower. Even if ALL the trace gases leaked out, thats still only 1% of the volume, or pressure, hence .5 psi. Simple science, and alot of sheeple falling prey.

[kman]

Originally Posted by Ridley

[p+a(n2/v2)](V-nb)=nRT

V is the total volume
a is a measure of the attraction between the particles
b is the volume enclosed within a mole of the particles b = nAb',
n is the number of moles,
R is the gas constant

And using the established van der waals constants of:


% composition of air
N2=1.39 78.084%
02=1.36 20.947%
Ar=1.34 .934%
co2=3.59 .033%

You can see that at normal temperature fluctuations seen in tires, "air" and pure nitrogen will result in pressure variations of less than 1%. That would be the equivalent of ~1/2 psi at 50 psi

However, if you add a significant percentage of water vapor... with a van der waals constant of 5.46, you could see fluctuations of up to 5-7%, which is still absolutly irrelevant in a street car, but may have a slight disadvantage in a racing application where extreme temperature fluctuations in the tire occur and minute pressure variations have adverse handling effects.

SO, I'll reiterate.......Nitrogen is a scam. Most comercial compressors, have efficient air "dryers", so h2o vapor is not an issue. Now, if you have a hillbilly deluxe air compressor that has a tank full of water cause it's never been drained............N2 would be a good investment

The 20$ or so spent on the nitrogen scam, would be much better spent on an oil change

Ok, i like your math, you win. Question - given the choice, if nitrogen was free, would you choose it over air?

[helomech]

Originally Posted by kman

Ok, i like your math, you win. Question - given the choice, if nitrogen was free, would you choose it over air?

I have free nitrogen at work, we have to use it on the helicopters, and I have never used it on my tires.

[Ridley]

Originally Posted by kman

Ok, i like your math, you win. Question - given the choice, if nitrogen was free, would you choose it over air?

I wouldn't care one way or another to be honest. I would contaminate it air from my compressor eventually anyways, lol. As I air down occassionally for offroad, it wouldn't last long regardless. I just hate seeing people get ripped on snake oil, so I tend to speak up. Can't beat free though..............can barely find air for free these days, lmao

[Carbeaux]

From Wikipedia:

Nitrogen molecules are less likely to escape from the inside of a tire compared with the traditional air mixture used. Air consists mostly of nitrogen and oxygen. Nitrogen molecules have a larger effective diameter than oxygen molecules and therefore diffuse through porous substances more slowly.[4]

The footnote being:

^ G. J. Van Amerongen. The Permeability of Different Rubbers to Gases and Its Relation to Diffusivity and Solubility. Journal of Applied Physics 1946, 17, 972-985. DOI:10.1063/1.1707667.

Just another source for consideration.

[Nuke]

Originally Posted by Carbeaux

From Wikipedia:

Nitrogen molecules are less likely to escape from the inside of a tire compared with the traditional air mixture used. Air consists mostly of nitrogen and oxygen. Nitrogen molecules have a larger effective diameter than oxygen molecules and therefore diffuse through porous substances more slowly.[4]

The footnote being:

^ G. J. Van Amerongen. The Permeability of Different Rubbers to Gases and Its Relation to Diffusivity and Solubility. Journal of Applied Physics 1946, 17, 972-985. DOI:10.1063/1.1707667.

Just another source for consideration.

Wow, so molecule size is not strictly a function of atomic weight? That is good stuff. Got to love wiki. I found another source that says basically the same thing. From the report referenced by wiki, Table 2, page 6, at 50 degrees, if you look strictly at solubility in natural rubber, oxygen is 0.106 and nitrogen is 0.060. That would make air 0.069.

Ignoring permeability, where nitrogen has even less of an advantage, what does that mean? Assuming your leakage through the tire wall is, say 10% per year with air. It's nowhere near that, probably closer to 1%. But just for argument's sake, 10% is 3 psig/year, then you could cut it down to 2.6 psig/year, for a savings of 0.4 psig/year using nitrogen versus air. At best.

[jgio]

Just came from the dealer and they comp'd me all 4 tires with nitrogen, I can honestly say I feel the difference in the road. But all I do is Day to Day driving and haul some horses around. BTW only have OEM tires.