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dpb

On 11/06/2014 11:46 AM, wrote:
....

The use of nitrogen inflation actually started with aircraft tires.
Where it DOES make a significant difference. EXTREME temperature and
pressure differences during every takeoff and landing.

But that's not the reason for using it--it's still an essentially ideal
gas at those pressures (roughly 200 psi) so the pressure fluctuations
are no different than with air (which, remember is 80% N to start with).

The reason is to eliminate the entrapped water vapor that can turn to
ice crystals at high altitude. I suppose there's a very slight
improvement in minimizing pressure loss owing to diffusion at the low
pressure of high altitude since N permeability is about a third less
than that of O, but given the duration of flights and the religiosity
with which stuff is checked I really doubt the effect would be
measurable within the allowed precision.

The same effect could be accomplished by purging and using dry air or
any other (non-explosive) gas with a molecular weight as great or
greater than O2 as long as one displaced the air vapor in free air.

It's those secondary effects that are the only real benefits that is why
for ordinary application in passenger car/light trucks it's _way_
overkill in that there just won't be any discernible symptoms that it
cures that ordinary care and maintenance don't resolve, anyway.

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