At 07:10 PM 6/17/97 -0700, you wrote:
>Said he fitted a new set of tires each race day to each of the 5 vintage
>Mustangs under his wing. After sucking the air out, he replaced it with
>Nitrogen, because "using Nitrogen to inflate the tires, the tire
>pressure increase whem hot was only 20% of tire pressure increase using
>air"
>
>Have some laws of physics been repealed?, or perhaps they don't work at
>weekends at race tracks, or is there really something going on here?
>Malcolm Cox Napa CA 1960 MGA
>
>
Actually, any dry gas would work. I checked with our local bottled gas
man, and I believe the
real reason nitrogen is used by all the teams, is economics. Nitrogen is
about $26 per 300
cubic feet, and air (not oxygen, but air, the mix) is $32.
It *is* true that you local compressed air from home or the gas station,
will have water
vapor in it, and *that* is what heats up and expands to a great extent, and
not knowing what
the humidity is leaves the expansion ratio unknown. So they use a cheap,
dry gas, i.e. nitrogen.
|