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Old 31 May 2011, 11:37 PM
jimmy101_again jimmy101_again is offline
Join Date: 29 December 2005
Location: Greenwood, IN
Posts: 6,872

Originally Posted by overyonder View Post
What I find amusing is that there's no real good way to remove all of the old air from inside the tire when filling it. They don't use a vacuum pump and draw out all the old air out. The easiest way to fill a tire with only one gas would be to dismount the tire, and force-flush the tire with Nitrogen (or other) and seat the tire on the rim while it's being flushed. And I can pretty much guarantee that shop guys don't dismount a tire when filling with only Nitrogen!
This is a common problem in chem labs, exchanging air in a vessel with an inert atmosphere. The solutions is easy enough even without a vacuum pump. For a tire you fill and vent the tire a couple times. Figure the tire is at 15 PSI (absolute pressure) and you take it to the recommended 45 PSI (again absolute, not gauge, pressure). The tire now has about 6% oxygen in it. You vent and fill again with pure nitrogen and the oxygen content will be around 2%. The water content will be well below 1%. Repeat however many times you wish. Each fill / vent cycle will reduce the oxygen content by about 2/3rds of the previous cycle.
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