Do you use nitrogen?

[OpenClimb]

As for GA aircraft, I can say that I've never seen anyone fill their tires with anything other than regular 'ol air. This being said, however, for most people, it's necessary to check the tire pressure at fairly regular (frequent) intervals.

I know a bunch of people with tight-fitting wheelpants who really dread the process (myself included). Depending on the availability/storage/price of getting an air tank filled with nitrogen, I'd seriously consider doing this to avoid removing my wheel pants so often to check/maintain air pressure.

They sell "no leak" tire tubes for use in aviation. I've never really understood this. Kind of like a waterproof umbrella, if you asked me. Oh, so you want the tubes that actually _retain_ air...

Hmm. Something to consider...

 

[Thedude]

First off, from a chemistry point of view, Nitrogen has a lower atomic weight that Oxygen.

Secondly, Oxygen is never found in nature as a single molocule but nitrogen is. (So water should really be written H4O2 but isnt for mathmatical ease of use). So the theory of bigger molecules is backwards.

Third, Nitrogen is inert. So that mean relatively resistant to changes in temp or delta T. Dalton's Gas Law PV=nRT. So that mean you dont have a large change in pressure over a large range of tempatures.

Fourth, nitrogen being inert plays again. Meaning that it has a less corrsion rate that regular air. This being a secondary reason.





I swear I will try to stop posting will I have been drinking so I can form more complete thoughts

 

[A Squared]

Nitrogen is inert, it will not burn, also it is less corrosive than regular air because of the moisture issues and because it is inert. Bigger Molecules, Seriously, Come On. Bigger molecules? WTF!

P.S. All of you with bigger molecules go get me a bucket of propwash and some flight line.

A couple of things. Nitrogen is not inert. Ever hear of nitrous oxide? Ammonium nitrate? Any of a multitude of other nitrogen compounds? Inert elememts don't form compounds, and elements which form compounds aren't inert. Nitrogen is less reactive than say oxygen, but it is far from inert.

As for the molecule size, all your sneering accomplishes is to underscore your ignorance. Yes, molecules come in different sizes. A molecule of helium gas is much smaller than say a benzene molecule. And, yes, oxygen and nitrogen travel through membranes at differing rates, in fact some facilities use this to seperate air into nitrogen and oxygen for industrial purposes. Most of the information I have been able to dig up indicates that nitrogen will travel through the tire 30 to 40% slower than oxygen. Whether this is due to molecule size, or some other reason, I don't know. I would reccomend, however, that before you start scoffing at what others say, you educate yourself on the subject, just a little.

 

[tomgoodman]

Record for amount of nitrogen used on one airplane?

We had a modified NKC-135 at Patrick AFB back in the early '70s which carried a 300 gallon tank of liquid nitrogen (to cool a sensor mounted in a "doghouse" on the upper fuselage). This was an early "star wars" project called Midcourse Acquisition and Tracking System. A "sniffer" alarm was installed to warn of leaks which could cause fatal hypoxia. The Airborne Laser Lab was even worse--fuel for the chemical laser was poisonous!

 

[A Squared]

First off, from a chemistry point of view, Nitrogen has a lower atomic weight that Oxygen.

True, but not particularly relevant. Nobody has mentioned molecular weights.

Secondly, Oxygen is never found in nature as a single molocule but nitrogen is. (So water should really be written H4O2 but isnt for mathmatical ease of use). So the theory of bigger molecules is backwards.

Wrong, on many levels. Nitrogen gas is a molecule composed of 2 nitrogen atoms, just like oxygen gas is two oxygen atoms. The oxygen atoms can be split part quite easily. Ever hear of carbon *MON*oxide? The "mon" means one, as in one oxygen atom. It is CO, not C2O2. The idea that a water molecule is really 4 hydrogen atoms combined with 2 oxygen atoms is completely absurd. Chemical notation is very precise, if there are 2 atoms, the notation shows two atoms. You do *NOT* divide by a common denominator for "ease of use" If so, benzene, which is 6 carbon atoms and 6 hydrogen atoms would be CH. It is not, it’s C6H6. And lastly, the size is not "backwards". A nitrogen gas molecule is in fact larger than an oxygen gas molecule; 23.6 cubic angstroms for a nitrogen molecule as compared to 22.5 for an oxygen molecule.

Third, Nitrogen is inert. So that mean relatively resistant to changes in temp or delta T. Dalton's Gas Law PV=nRT. So that mean you dont have a large change in pressure over a large range of tempatures.

Again, wrong on so many levels it’s difficult to know where to start. Nitrogen is not inert, it is less reactive than oxygen, but not inert. Regardless, the chemical reactivity has absolutely no bearing on how "resistant to changes in temp" a gas is. The "resistance to change in temp" (specific heat) of nitrogen is only about 3% different than the specific heat of air, in other words, not a significant difference. If being "resistant to changes in temp" was beneficial, we’d use hydrogen which is 14 times more resistant to changes in temp for a given heat input. Next, PV=nRT is the Ideal Gas law, not Dalton’s law which deals with partial pressures. Aside from that, the change in pressure due to temperature change is approximately the same for Nitrogen and Oxygen. they both behave very much like an ideal gas at low pressures. Oxygen differs the most from an ideal gas, but even at 10 atmospheres (approximately 150 psi) the difference between nitrogen and oxygen is less than 2 percent, again, not enough to make any real difference.

Fourth, nitrogen being inert plays again. Meaning that it has a less corrsion rate that regular air. This being a secondary reason.

Well, nitrogen *still* isn’t inert, but it won’t oxidize metal. Also, nitrogen gas, because of the manufacturing process contains no water vapor, unlike compressed air, which contains quite a bit of water vapor. The water vapor also contributes to the corrosion.

I swear I will try to stop posting will I have been drinking so I can form more complete thoughts

Good plan, Maybe you can remember chemistry a little better when your sober, but almost everything your wrote while drunk is incorrect.

 

[Gorilla]

Asquared is correct. The use of bottled nitrogen gives 2 distinct advantages...

It is BONE dry due to the industrial process when it is bottled. Less water = less corrosion.

It is FAR LESS reactive than air. In many ways, Nitrogen gas in this situation (contact with rubber and metals) can be considered inert, although it is a far cry from a noble gas like Helium.

All the other arguments may have a tinge of merit but fall far below these in importance.

You can probably replicate at least the moisture advantage at home or hangar by fitting your air compressor with moisture traps and scrubbers. If you are a welder, you know that you can buy huge bottles of either Argon or Nitrogen for not all that much money. Argon is used as a shielding gas in welding, and by definition must be 100% free of moisture. I'd bet tires filled with Argon would kick some butt.

 

[siucavflight]

Nitrogen freezes at a lower temperature. It also retains a constant pressure over large temperature changes. On top of that it does not contain moisture, unlike the ambient outside air. If outside air is pumped into an aircraft that flies above the freezing level, the moisture within the air will freeze inside the tire. This can cause an imbalance or corrosion.

Also, aircraft tires are designed to resist nitrogen permeation though the carcass.

He hit all of the reasons. Nice post Russian.

 

[Imperium]

I know that Nitrogen is used in racing for similar reasons it is used in aviation, as The_Russian has stated. Although in racing the issue is the moisture content relative to the high temperatures on track. Ambient air, especially in the south, is high in moisture. Once the tire gets up to temp, all that water turns to steam and you can have a blow out. Ambient air is 76% Nitrogen anyway, but it was always about the moisture content. Since tire psi was changed many times on the car, over the course of a weekend, the constant pressure issues were less important.

 

[tracearabians]

Yes! Nothing but Nitrogen in the tires and struts.

This article says airplanes use nitrogen in their tires. Maybe by the majors and the Air Force but I've not seen it.

Do you fill your tires with nitrogen?

http://tinyurl.com/k6azr
or, in its long form
http://www.theeveningbulletin.com/site/news.cfm?newsid=16819555&BRD=2737&PAG=461&dept_id=576361&rfi=6

. Ed

 

[A Squared]

He hit all of the reasons. Nice post Russian.

Yeah, nice post, except for the fact that the majority of it is fantasy.

Nitrogen freezes at a lower temperature.

Uhhh, right, Nitrogen turns to liquid (not *freezes*, turns liquid) at -195.8C, air at -194.3C How often to you encounter temperatures like this? Not often, I’m thinking.

It also retains a constant pressure over large temperature changes.

Uhhhh, noooooo. The pressure of Nitrogen varies with temperature, just like any gas. It is still subject to PV=nRT. In fact, the pressure of nitrogen varies *more* than the pressure of Oxygen. If you took two tires and filled one with nitrogen and one with oxygen to150 psi at standard temp (15C/59F) the nitrogen filled one would be 121 psi at -40 and 164 at 110F while the oxygen filled one would be 119 psi at -40 and 161 psi at 110F. While the difference is slight, (43 psi vs 42 psi) the pressure of Nitrogen actually varies *more* with temp, not less. The difference between nitrogen aid air would be even less as air is mostly nitrogen.

On top of that it does not contain moisture, unlike the ambient outside air. If outside air is pumped into an aircraft that flies above the freezing level, the moisture within the air will freeze inside the tire. This can cause an imbalance or corrosion.

Ahhh, finally, you got *something* right.

Also, aircraft tires are designed to resist nitrogen permeation though the carcass.

They are also "designed" to resist the permeation of oxygen, and any other gas.