Re: [Paddlewise] OFF TOPIC: Nitrogen in Racing Tires

From: Dave Kruger <dkruger_at_pacifier.com>
Date: Fri, 28 Aug 1998 14:19:19 -0700
Tom Dittrich wrote:
> 
> Just to keep the "nitrogen in racing tires" debate going a little
> further...here are some snippets I pulled from various web sites dealing
> with racing.  The primary reason seems to be that the water vapor in air
> is what causes the most expansion as tire temperature rises.  For other
> applications, such as air in tires with steel rims and perhaps also
> inside things like shock absorbers and struts, it avoids oxidation
> problems.
> 
> Tom
 
Well, it's probably about time to kill this thread.  It is "off topic,"
after all.

I read all the snippets, Tom, and as far as I know there were only two
valid points:

1. O2 in tires will add a (miniscule) amount of O2 to any fire, and may
accelerate degradation of the metallic parts inside tires (rims, etc.). 
I can't believe either of these is a significant reason for avoiding DRY
air for inflation.

2. The snippets claim water VAPOR will expand more than any other common
inflation gas (i.e., N2 or O2).  That's wrong.  Probably, racers avoid
compressed air right out of the compressor because it likely contains
misted water LIQUID (unlike DRY N2 from a tank).  And, yes, those water
droplets, as they convert to water VAPOR at racing temperatures, will
lead to a greater pressure increase than if they were introduced as
vapor.  That COULD be significant, liquid water has a volume roughly
1800 times smaller than water vapor (same mas of H2O).

'Spect I'm done with this, though I enjoyed the contributions, and Tom's
explained where the N2 mythology for racers began.  I expect if I could
corner the market on argon and get a similar myth going on its
superiority to N2 (argon atoms are round, after all, and so they should
not resist tire motion as they ricochet off the insides of tires, unlike
oblong N2 molecules), I could retire on the profits!

--
Dave Kruger
Astoria, OR
sea kayaker/chemist/one-time motorhead
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Received on Fri Aug 28 1998 - 14:08:25 PDT

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