""If you contaminate the nitrogen with even a bit of air during a pressure
adjustment, all nitrogen’s benefits are lost.""
So how can we possibly avoid any air at all from contaminating the mix in the
tire, obviously even a newly mounted tire will have air trapped in it? Joe :)
brian falkner wrote:
> I figure there's a big message here for Landspeed cars, tow vehicles &
> trailers so here is just about all you need to know on the subject.
> Brian
> 8888888888888888888888888888888888888888888
>
> This Research section contains information on the use of nitrogen gas in
> various applications.
> TIRE RESEARCH
> The following is an excerpt from a research paper prepared by Lawrence
> Sperberg concerning the use of nitrogen gas for tire inflation.
> Million Mile Truck Tires - Available Today
> "Oxygen- the Killer of Tires"
> by Lawrence R. Sperberg
>
> All pneumatic tires have suffered from a deterioration starting the day
> that tires were invented. That deterioration is chemical oxidation
> masquerading under the name of "tire fatigue".
> THE ENEMY - OXIDATION
> Causing the deterioration are oxygen molecules contained in the inflating
> air which is a mixture of gases - nitrogen 78%, oxygen 21%, argon 0.9%, and
> miscellaneous O.1%. Tires are designed to be protected from this
> deterioration by their liners which are supposed to keep air from
> percolating through them into the tire body, which they never do, and by
> chemicals called antioxidants or age resisters whose job is to intercept
> and neutralize any invading oxygen - which they do until they are
> themselves used up, which occurs too soon after a tire enters into service.
>
> So the deterioration spreads. It starts within the tire interior and moves
> outward. it first invades and consumes the tire liner. It then ravages the
> insulation rubber adjacent the liner. It marches inexorably outward -
> because of the pressure differential of the tire inflation on the inside
> and the atmospheric pressure on the outside. As the decay moves ever
> outward - the oxygen molecules react chemically with the unsaturated double
> valence bonds present in all rubbers, causing the rubber molecules to lose
> their strength and their elasticity, so that they no longer act as rubbers,
> but instead take on the characteristics of a non rigid plastic. The decay
> is constantly being fueled by the fresh all too often moist air being
> injected into the air chamber to maintain the desired inflation pressure.
>
> How do you get a truck tire to go a million miles? It's simple.
> TAKE THE OXYGEN OUT OF THE AIR!
> TRUCK TIRE TESTS
> A total of 175 truck tires were tested until they were worn down to the
> tread wear indicators (TWI). About 125 of these tires wore out without
> failing at mileages ranging from 125,000 to 225,000. About 50 of the tires
> failed physically at varying mileages generally on the low side. All the
> tires had been carefully monitored, measured for tread loss etc., and
> inspected at 10,000 mile intervals, a lot of them at 2000 to 3000 mile
> intervals. Tire sizes were mostly 11R24.5 & 11-24.5 with a very few 10R20
> and 10-20's. About half of the tires had operated over the eastern part of
> the United States while the other half had run mostly in the southwestern
> part of the U.S.
>
> When the tires were removed from service small samples of tread rubber were
> taken from the shoulders of the unfailed tires and from the actual failed
> areas of the destructed tires. These specimens were then subjected to the
> electron microprobe examination that has been described previously. The
> examination was specifically directed at determining oxygen and sulfur
> levels which was best accomplished by using IOKV (10000 electron volts)
> electron beam And an exposure of 30 seconds.
>
> Both of the figures tell the same story. When a tire lives to wear out, the
> oxygen slowly migrates and permeates its way into and through the tire cord
> body and finally into the under tread and then into the tread itself. It
> takes a long time for an appreciable amount of oxygen to reach the tread
> since most of the oxygen gets waylaid along the way by the liner, and then
> the cord arid cord insulation compound.
>
> One reason that truck tires can run 250,000 miles with the original tread
> while passenger tires can only go 50 to 60,000 miles lies in the relative
> bulk of the 2 different tire bodies. The bulkier the body the longer it
> takes for the oxygen to work its way into the tread. Unfortunately the
> bulkier the body the higher is the heat buildup and the faster is the rate
> of oxidation of the available double bonds. Once the tire body is all
> oxidized the tire is dead no matter how much tread remains on it. The
> thinner the tire body the lower the running temperature and the slower the
> rate of oxidation with a correspondingly longer life.
>
> Practically all tire engineers throughout this century attribute the
> gradual loss in tire strength to be the result of "fatigue" when in reality
> this "fatigue" is nothing more than a slow inexorable oxidation taking
> place at the available double bonds of the rubber molecules.
>
> IMPROVED TIRE LIFE
> In one experiment involving 54 new 10.00-20 truck tires, 33 were inflated
> with nitrogen and 21 were inflated with air. These tires were run side by
> side on the same tractor units until they failed or until they wore to the
> tread wear indicators. In this case the 54 new truck tires, nitrogen
> inflation resulted in 26% more miles being run before tires had to be
> removed when wear reached the tread wear indicators.
>
> In the case of the failed tires a smaller percent of nitrogen tires failed
> physically (30% vs. 57%) and they gave 48% more miles before failing than
> did the air tires. This 48% improvement is due to the tire bodies lasting
> longer and not the better wearing properties of the tread which is the
> situation with the tires that lived to wear out.
>
> The experiments involving 54 new and 44 used tires running some 7,345,497
> tire miles in drive axle service, when viewed in light of the election
> microprobe experimental findings presented earlier, depict a clear cut
> picture of what nitrogen inflation can do for the transportation industry -
> cost wise as well as safety wise.
>
> HOLDING PRESSURE BETTER
> Today probably 99% of all tires are tubeless - truck, passenger, giant -
> and these tires are inflated with air, and all too frequently with wet air,
> i.e. air where the water has not been drained from the compressor tank as
> it should be. This moisture laden air (oxygen catalyzed by water) attacks
> the paint in the wheel well ultimately penetrating the paint and oxidizing
> the iron below it to form iron oxide or rust. Even aluminum is not immune
> from rusting, forming aluminum hydroxide, that gives an extremely fine dust
> that is difficult to even see inside the tire. The iron oxide rust is
> present within the tire in varying sizes ranging from coarse to extremely
> fine. Aluminum hydroxide dust is never coarse only extremely fine.
>
> Whenever a tire is checked for its inflation pressure the pressure gauge
> requires a small gulp of air to activate the gauge. When the small gulp of
> air escapes from the tire the turbulence created picks up the finely
> divided rust and the dust enriched gulp of air passes around the open valve
> core which has been opened by the tire gauge. When the valve core drops
> backward into place after the gauge is removed some of the tiny rust
> particles get trapped between the rubber or plastic seal and the metal
> housing surrounding the seal.
>
> This results in an extremely slow air leak that all too often escapes
> detection by the person gauging the tire and unless a metal valve cap which
> has another sealing surface in it is screwed onto the valve stem the tire
> will continue to lose air, albeit very slowly. When a larger rust particle
> is trapped between the core and housing, the escaping air is easily
> recognized so that proper action can then be taken immediately to correct
> the problem.
>
> The perennial problem of low tire inflation can be effectively solved by
> the simple expedient of using nitrogen to inflate tires. Nitrogen is dry
> and contains no moisture. Nitrogen is inert so rust cannot form since there
> is neither oxygen nor moisture present to cause oxidation of the wheel.
>
> Copyright 1996 Lawrence R. Sperberg, Probe Forensic and Testing Laboratory,
> El Paso, Texas. All rights reserved.
> ---------------------
> One company, Generon, is planning to market small, nitrogen generation
> systems to the average consumer at a cost of approximately $300 for use in
> home garages.
> ----------------
> If you contaminate the nitrogen with even a bit of air during a pressure
> adjustment, all nitrogen’s benefits are lost.
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