Re: tire gas ....

Date:         17 Oct 99 23:29:51 
From:         "Fred" <>
Organization: Cyrix Corporation
References:   1 2
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<Delurking for basic chemistry>
>Nitrogen is an inert gas with a low coefficient of
>expansion.  It handles the cold soak condition a lot
>better than air.

Yes it is relativity inert.  But it is about as close to ideal
gas as air, so PV=nRT still.  So same coefficient of expansion.

> Nitrogen will not absorb any moisture.

Same as air (80% N2).  Absorption of moisture is function
of relative humidity or partial pressure of water vapor
and hence temperature only - not type of gas.

>nitrogen is not effected by temperature as much as
>regular air and will keep near the same pressure at
>altitude & different airfields.

See PV=nRT above.  Again effected same as air.

P - pressure
V - volume
n - number (amount) of gas
R - fudge factor to make the units work out
T - temperature

So for aircraft,
V - fixed for the most part
n - fixed unless the tire needs fixing
so you basically have:
P = T

Raise the temp and the pressure goes up.  Independent of the
type of gas.

Air, at the temperature and pressures we normally see, including
aircraft tires, is VERY close to an ideal gas.

-- Fred