Why nitrogen?

It all sounds like BS to me- if it's the tire we're discussing, there's no
contact with the nitrogen, just the inner tube. The outer surface of the
tire is in air of course, along with exposure to UV light, salts, etc. The
tire is going to lose its rubber well before it starts to oxidize and crack.

A tube perhaps might be more subject to oxidation, but it's dark in there,
not a lot of UV to make stuff that cause oxidation like free radicals and
ozone, and the increase in the partial pressure of oxygen at 200psi is only
around 15fold, or from around 140mm Hg to around 2000mm. If it'sdry air, I
can't believe it would make that much difference.

Need to see the aging data on rubber kept in air versus nitrogen.

Just realized I was starting to sound like you know who, so will stop this
and have another cocktail.

"Viperdoc" wrote in
:

It all sounds like BS to me- if it's the tire we're discussing,
there's no contact with the nitrogen, just the inner tube. The outer
surface of the tire is in air of course, along with exposure to UV
light, salts, etc. The tire is going to lose its rubber well before it
starts to oxidize and crack.

Yeah, I kinda thought that myself which gave me the notion that the fire
thing wiht heavies might be more relevant we run anything up to 300PSI as
well, which might be a factor. I must ask around again.



Bertie

I don't know whether nitrogen alone versus plain old air would make that
much difference in supporting a fire. As I recall, the heavies have blow out
plugs in case of a hot brake, so the plug melts and lets the air (nitrogen)
out before the tire blows.

On our base they fill the KC-135 tires in a big steel mesh cage- kind of a
reminder of what could happen if it let go.

Reminds me of the time a line guy in a local airport filled the air bottle
for a Vendenyev engine (they use an air start and not an electrical starter)
with oxygen rather than compressed air. The resulting fire burned up the
whole plane. The initial start-up must have been something to watch-
ignition on, engage starter, two blades, .... then kaboom!

At least it was in a Wilga, and not an aerobatic plane. It was the aviation
equivalent of Darwinism- ridding the world of ugly airplanes.

"Viperdoc" wrote in
:

I don't know whether nitrogen alone versus plain old air would make
that much difference in supporting a fire. As I recall, the heavies
have blow out plugs in case of a hot brake, so the plug melts and lets
the air (nitrogen) out before the tire blows.

That's right. they do, but they can and do catch fire as well.

On our base they fill the KC-135 tires in a big steel mesh cage- kind
of a reminder of what could happen if it let go.

Reminds me of the time a line guy in a local airport filled the air
bottle for a Vendenyev engine (they use an air start and not an
electrical starter) with oxygen rather than compressed air. The
resulting fire burned up the whole plane. The initial start-up must
have been something to watch- ignition on, engage starter, two blades,
.... then kaboom!


wow!


At least it was in a Wilga, and not an aerobatic plane. It was the
aviation equivalent of Darwinism- ridding the world of ugly airplanes.


So, the O2 fueled an already existing fire or caused it?


Bertie

"Viperdoc" wrote in message
...
...

Need to see the aging data on rubber kept in air versus nitrogen.


I've seen it at work, fwiw. Some difference.

But, for car tires, I would say there is more hype than benefit.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

"Capt. Geoffrey Thorpe" The Sea Hawk @See My Sig.com wrote in
:

"Viperdoc" wrote in message
...
...

Need to see the aging data on rubber kept in air versus nitrogen.


I've seen it at work, fwiw. Some difference.

But, for car tires, I would say there is more hype than benefit.


Used to put it in the tires of my light plane, mostly because it was free.
I flew off grass and reckoned they'd rot before I wore them out anyway, so
I might as well get the most bang for the buck out of the tires.


Bertie

"Bertie the Bunyip" wrote in message
...
"Capt. Geoffrey Thorpe" The Sea Hawk @See My Sig.com wrote in
:

"Viperdoc" wrote in message
...
...

Need to see the aging data on rubber kept in air versus nitrogen.


I've seen it at work, fwiw. Some difference.

But, for car tires, I would say there is more hype than benefit.


Used to put it in the tires of my light plane, mostly because it was
free.
I flew off grass and reckoned they'd rot before I wore them out anyway, so
I might as well get the most bang for the buck out of the tires.


Bertie

You're a cross posting dumb ass.

On Sep 15, 3:09*pm, "Viperdoc" wrote:
The thread on brakes raised a question from the past- why nitrogen in the
tires of big jets and heavies? Air is around 78% nitrogen anyway, and the
coefficient of expansion of the remaining 20% that's oxygen can't make that
much difference in volume.

Why not just use dry air? I couldn't imagine that dry air or dry nitrogen
could make that much difference in corrosion, either.

I seem to recall someone giving me the rationale for this a long time ago,
but also seem to remember thinking it didn't make that much sense at the
time.

I just got new tires for my wife's car. They're usnig Nitrogen too.
They put green caps on the valve steam to show its not air.

-Robert

Everything posted so far leads me to believe that dry air should work just
as well as dry nitrogen.

At least it's about aviation.

"Robert M. Gary" wrote in message
...
I just got new tires for my wife's car. They're usnig Nitrogen too.
They put green caps on the valve steam to show its not air.

Yes, those green caps have proven to be much better at keeping the snake oil
inside the tire where it belongs. Also, I have never once seen a car with green
valve stem caps get attacked by elephants, (but that is just anecdotal evidence
and your experience may vary).


--
Vaughn

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