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Old 11-25-2004, 10:37 AM
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Quote:
Originally Posted by Rlockyer
I'd be interested in a reference to support that.
You're already running nearly 80% nitrogen with air. Nitrogen's properties are not much different than oxygen. Nitrogen has an atomic weight of 14, 7 protons, and oxygen has an atomic weight of 16, 8 protons. Both turn from liquid to gas at 298k.

In comparison with helium, helium is far less compressible than oxygen, and the result is that pressure variations as a result of temperature differentials far exceed that of air. When filling a scuba tank, we'll typically go 10% over our target pressure on helium to get the mix to come out right after it cools.
I mention helium because helium is lighter than both oxygen and nitrogen, and nitrogen is lighter than oxygen.

(P1 x V1)/T1 = (P2 x V2)/T2 (temperature in K)
If temperature increases, either pressure or volume (or both) must increase.

Ah. Nice to hear a technical side. I am just repeating what I have heard from some of the race teams I have talked to. The guy that manages the cars variables, including tire pressure, said that they saw less variation in pressure with tire temperature with nitrogen than with regular air.

It may have been the track conditions that they were testing on were giving substandard results.
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