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Parker Hannifin Joins Get Nitrogen Institute to Promote N2 Tire Inflation

26 October 2006

Parker Hannifin Corporation has joined the Get Nitrogen Institute, a non-profit organization formed in 2005 to promote the use of nitrogen rather than air in filling tires. (Costco, the first retailer to offer nitrogen in its tire centers throughout North America, is a sponsor of the Institute.)

The use of nitrogen in tires offers two main benefits: the maintenance of a consistent inflation pressure over longer periods of time and longer tire life. Those lead to improvements in fuel efficiency of up to 4% compared to vehicles running on underinflated or degraded tires.

Maintaining the appropriate inflation pressure in tires is one of the basic techniques in optimizing fuel efficiency in a vehicle. Nitrogen permeates through the tire at a rate of 35% slower that oxygen (air). The lower permeability results in higher pressure retention.

Nitrogen is also a dry gas and disperses heat more rapidly, resulting in cooler-running tires. It also significantly slows the chemical aging process associated with oxygen and the moisture contained in the compressed air. A study by Ford presented to the Rubber Division of the American Chemical Society found that the use of N2 as the inflation medium significantly slowed down or even halted changes in rubber properties over time.

Nitrogen tire inflation is used in the aerospace and racing industries and is also beginning to make inroads into the long-haul trucking industry.

Parker Hannifin makes nitrogen generators, and has more than 10,000 in operation worldwide. It produces N2 generators for auto and tire dealers under the TireSaver and TireSafe brand names.

The generators use hollow fiber membrane technology to purify air into a stream of high purity nitrogen. This technology is also being used to generate nitrogen gas at the point of use for a wide variety of applications including general manufacturing, food processing and packaging, chemical blanketing, and chemical analysis.

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October 26, 2006 in Fuel Efficiency, Tires | Permalink | Comments (20) | TrackBack (0)

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Question: if nitrogen permeates through the tire rubber 35% slower than oxygen, then if you simply fill up with air (78% nitrogen) and top off regularly, won't you eventually have close to pure nitrogen (with a bit of argon and CO2, depending on their permeation rates) in your tires? Am I missing something here, other than an opportunity for a company to sell a product for an invented "need"?

http://en.wikipedia.org/wiki/Earth's_atmosphere#Composition

Regular air is already 78% nitrogen. As said above regular top offs will increase this amount. There seems to be very little need for this.

About all I can see as the advantage is the lower moisture content.

Longer lasting tires->fewer blowouts->fewer deaths.
Longer lasting tires->fewer tires to dispose of->less waste.

The question becomes feasibility and costs. It seems to be a waste to use such gas generating technology just for tire inflation. Perhaps resulting the O2 rich gas (air stripped of N2 is O2 rich) can be use for something, like diesel electric generator.

The way I'm reading this article, pure nitrogen has the advantage of having no oxygen or water vapor to react with the interior rubber, in addition to the permeability.

Ergo, the tire lasts longer and needs to be topped off less often.

Nitrogen gas is usually produced by chilling air until the N2 fraction liquefies. Whoever came up with this idea should specify the energy cost to produce & distribute the nitrogen gas and demonstrate a significant net benefit due to improved tire inflation and life.

Note that all cars equipped with ABS (and very few are not) already measure the radial velocity of each wheel and the steering angle. This information permits the inference of unequal tire pressures. The requisite software is an available options on certain cars on the European market today, to alert the driver to a leak.

If the bulk of pressure loss is equal on all four tires, automated detection requires extra hardware, e.g. pressure transducers with wireless transceivers mounted on the inside of the rims. I don't know if such hardware can already be implemented as a passively powered RFID.

"Usually" isn't "always".

Medical oxygen concentrators use membrane technology to separate air and send the oxygen-rich stream to the patient.  The other stream is oxygen-poor and could be compressed for use in tires.  The design of a machine to concentrate nitrogen will be somewhat different, but the materials are the same.

Tire Pressure Monitor Systems (TPMS) transmitters are usually battery-powered.  They manage by transmitting short bursts at very low power and sleeping the rest of the time.  Some use centrifugal switches to reduce the transmission rate when not rolling.

Rafael, a large and increasing number of cars and trucks (especially SUVs with their perceived and real rollover risks) sold in the US have the same sort of tire pressure monitoring you describe. As you note, it won't detect if all four tires are equally low. I believe that some form of tire pressure monitoring is going to be required for all new vehicles sold in the US within a year or two. I'm not sure whether the ABS-sensor type system will satisfy this given its inability to detect four low tires, but I suspect that will be the dominant system if it is permitted.

As for the main discussion, I see the benefit of having pure N2 free of water vapor in the tires, but I just wonder if it is a significant enough benefit to justify the cost and hassle. It sounds a lot like a scheme to corner the market on tire inflation, something which has historically been 100% free from an air compressor hose at most gas stations in the US (aka "service stations" back from the day when they offered something that could be termed service).

I don't know about you guys, but my treads wear out long before the carcass does. Looks like a solution looking for a problem.

The most common reason for tire replacement is tread wear. The second common reason for tire replacement is side-wall puncture that is not repairable in tubeless tires. Since N2 tire inflation can't address these two most common reasons for tire replacement, then its benefit may not be significant, unless proven otherwise by a randomize controlled study of thousands of cars, similar to a large medical trial involving randomized placebo-controlled methodology with sufficient N number of subjects to arrive at a statistically significant result.

Now, if large studies prove a statistically significant advantage of N2 vs air inflation, would a mixture of 78% N2 and 21% CO2 be just as good, since O2 is not present, and CO2 is a larger molecule than O2 and hence less permeable and is totally inert? If so, then this new mixture can be very cheaply obtained by low-temp catalytic reaction of propane or LPG with air to produce CO2 and N2 mixture, and chilled enough to remove nearly all the moisture (H2O). Should be a lot cheaper than pure N2.

CO2 doesn't dissipate heat as well as lighter molecules.

Zach, you're talking about the systems based on ABS speed sensors.  These can detect small differences in tire circumference (and thus pressure variations over a certain amount), but you can also get TPMS which uses real pressure sensors in each tire.  Those read absolute pressure.

(Yes, I know from experience.  I wrote a signal demodulator for one of those things!)

TPMS also becomes required by law on all vehicles in 2008 or something, so underinflated tires will become less and less common since drivers will be alerted to the situation by the car's monitoring now.

Parker Hannifin joining Nitrogen Institute to promote nitrogen use because, Parker Hannifin makes nitrogen generators. Pretty obvious! Kinda like cattle ranchers promoting steak houses, because they sell beef! I dont see what the news is here.

I also dont perceive much of a benefit of widespread nitrogen use, for most people. Alot of the cars I see driving in my area idiotically run tires with low air pressure. Most arent into maintaining their cars. Why would nitrogen change that? Also, would they be diligent in staying with nitrogen, or would a portable air compressor, or much worse, a can of fix-a-flat ever be used again???

Nitrogen does have benefits for race cars, nonetheless. I know nascar uses it. Most likely the open wheelers too. But the average Joe?, No.

This just in: ethanol good for cars, say corn producers

Roger -

incorrect tire pressure accelerates treads wear (in the center for overpressure, on the edges for underpressure). The effect is much more pronounced for low pressure, though. If using N2 (or cooled exhaust gas, as you suggest) reduces the rate at which tires lose pressure, this would impact tread wear. Note that SUV tires are designed for off-road use and inflated moderately for that reason. If you never take you SUV off-road and stick more or less to the speed limit, you may want to exceed the recommended tire pressure by up to 10%.

Btw, incorrect alignment produces asymmetrical wear patterns. Regular tire rotations can mitigate that, especially on sports cars: tires rated for high speeds are made from softer rubber blends. If you own such a vehicle for looks and never drive much above 100mph, consider switching to tires with a lower speed rating to save both fuel and money.

Rafael,
Agree that incorrect inflation can cause abnormal tire wear. However, how much an impact would N2 inflation help to reduce incorrect inflation remains to be seen. This is because both N2 and O2 permeate thru the tire, both being gases, with N2 a little less permeable, only 35% less.

In the Ford pdf document, the emphasis seems to be on preventing rubber oxidative degradation rather than reducing air loss. Of course, if oxidation occurs, the O2 will be consumed and perhaps incorporated into the rubber and will be loss.

But, at any rate, the owner should still check tire pressure at regular interval and can't depend solely on any other way. I found that a quick vision inspection can be quite good at estimating the degree of air loss if an air gauge is not immediately available. That's how I've been able to keep my tire always adequately inflated. This skill should be taught to all drivers, and tires should be inspect at every fueling or before every ride if time permitting, to avoid potential dangerous hazard due to tire blow-out. Too much hype on pure N2 tire inflation can give the driver a false sense of security, and IF this will lead to less frequent tire inspection, visually or with an airgauge, then it may do more harm than good!

Nitrogen for "dry-air"? Please inspect the tire places when they change your tires. Most of the time I see them use a "soapy" solution to ease the mounting of tires on the rims. Therefore, if they use this technique of getting the tire wet prior to mounting, having N2 for the purpose of "dry-air" inside the tire is nonsensical and defeated by the mounting technique.

There are a number of tubeless tire systems for bicycles that use aqueous sealants in quantities of ~60ml for a mountain bike wheel. This quantity of water will typically diffuse out over a span of weeks to several months. I would expect water introduced into a car tire to diffuse as well, especially given the much higher temperatures involved. My understanding of the reason for N2 inflation is that it is mainly about dryness. Water in a tire undergoes a huge PV change as the tire warms because of the phase change. Obviously this would be something you would prefer to avoid. It would seem that one could simply use a dryer on the compressed air line. The fact that the tire installers drench the bead in soapy stuff is a bit of an issue, eh? Regarding N2 diffusing 35% slower than O2, is that measured in a relevant experimental setup, or did that come from the marketing department? Thermal conductivity differences between air and N2 are negligible. air = 0.026 W/mK, N2 = 0.026, pure O2 = 0.027. If you want better thermal conductivity, fill your tires with helium or hydrogen. Be prepared to fill often, because those little suckers leak like crazy. Chemical degradation? Ozone is probably more of a problem than oxygen, and the exterior of the tire is constantly bathed in air and zapped with uv. Nevertheless, I don't find rubber degradation to be the problem it once was. I think that tire makers may have that problem solved. IMHO, the N2 inflation thing is a scam, other than the fact that it's dry.

The process for the tire installation is the same the fill method is changed. The tire is mounted normally using regular compressed air. The tire is then deflated and inflated 2-3 times at lower than normal pressures 15-25 psi. Then finally filled with Nitrogen. This process "purges" the moisture and other impurities from the tire. Nitrogen is used on aircraft tires for the very reasons mentioned here. The tempreature changes are so great in coming down from 20,000 ft to slamming into the ground in excess of 100 miles an hour then stopping. Regular compressed air would never take the abuse and burst the tire.

I myself have been looking around this is some good information

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