Walmart Using ISG Nitrogen System for Tire Inflation Program
27 May 2010
Walmart has selected Inflation Solutions Group (ISG) to provide nitrogen tire inflation systems for its fleet. (Earlier post.)
|
|
| ISG nitrogen tire inflation system. Click to enlarge. |
As of April, ISG said in a press release, 28 of Walmart’s 54 fleet service centers are using the ISG nitrogen system, with installation of the system due to be complete and the remaining centers by the end of this year.
Nitrogen tire inflation can provide savings in fuel consumption and tire wear.
(A hat-tip to Bill!)
Resources
My tires are inflated with nitrogen and not only am I saving gas I spend less time correcting the pressure.
Posted by: ai_vin | 24 May 2010 at 12:35 PM
Do you have a N2 bottle at home with which to top them up or do you take your car in periodically?
Posted by: Sanity Chk | 24 May 2010 at 02:12 PM
Ah, this is a question that has interested me for years.
ai, I'd be interested in seeing your data on improved gas mileage. Also, by any chance did you capture data on tire pressure change over time?
And I don't understand the mechanism for better performance with nitrogen. How does a gas molecular weight of 28 (nitrogen) instead of 29 (air) save gas mileage.
Is it the 3% mass difference? In a normal auto tire, the mass difference would be less than 0.008 pounds, or less than 4 grams.
Both are diatomic molecules, so the ratio of specific heats are both 1.40. That means there won't be any difference in temperatures or heat accumulation due to compression.
Is it a difference in diffusion rates of 99.9% nitrogen / 0.1% oxygen mixture over a 79% nitrogen / 21% oxygen of air? Theory says that smaller nitrogen molecules should diffuse just a smidgen faster than oxygen through the rubber walls, but I've never seen data or discussions about oxygen accumulation over time inside tires.
Now, perhaps the moisture content of most ambient air might have some effect on tire life. But if moisture is the important variable, won't it be cheaper to dry the air than to both dry the air and separate nitrogen from air?
I just don't understand. Can anyone explain why 99.9% nitrogen is better than 79% nitrogen?
Thanks.
Posted by: WVhybrid | 24 May 2010 at 05:11 PM
99.9% nitrogen isn't going to react with tire compounds, losing pressure and stiffening the rubber.
Posted by: Engineer-Poet | 24 May 2010 at 06:53 PM
Condensation increases tire pressures, so nitrogen should allow you to run higher cold pressure, so your typical running pressure will be higher without exceeding safe limits.
Just Google: Ferrari nitrogen tires run cooler
Also, see these links:
http://forums.autosport.com/lofiversion/index.php/t96822-50.html
Posted by: GdB | 24 May 2010 at 07:05 PM
Sorry...100%(or 99.9) nitrogen for the average joe and the average car is one of the biggest NOT cost-effective hoaxs out there. Just make sure your rims are sealed, ya got no nails and adding 2psi will go much further than all the free nitrogen ever.
Show me positive data on FLEET garbage trucks, busses, OTR tractors and semis and Ill believe.
Posted by: fred | 24 May 2010 at 07:44 PM
Well, nitrogen is lighter than air or oxygen but it's the size of the molecules that count. Nitrogen molecules are larger in size than oxygen molecules and therefore, are less likely to leak or escape through the tire valve. Nitrogen filled tires have better and more consistent 'air pressure' which consequently, aid the vehicle's fuel efficiency (even if it is by a small margin). But it's not just about the nitrogen. It's about reducing oxygen, water vapor and other gases. Depending on tire temperatures, the water vapor in the air undergoes changes in pressure, which results in varying tire pressures. This is not an issue in case of nitrogen filled tires. Oxygen and water vapor also react with the insides of the car tire, i.e., with the rubber as well as the metal rims, and gradually lead to development and deposition of rust. This has an adverse effect on the longevity of the car tire. Nitrogen does not react with the car tire insides or with the rim, thereby enhancing the life of the car tire. In the long term you're saving money.
Does it cost more in the short term? For me, no. Where I live the air[79% nitrogen/21% oxygen] pumps at the gas stations are coin operated but my tires are checked as part of my dealer's service plan.
Posted by: ai_vin | 24 May 2010 at 11:11 PM
Walmart should have gone straight to argon.
Carbon Dioxide is also available for most drink machines at most service stations.
Walmart built a distribution center in the US in the State of Utah about as far away from any railroad tracks that one can get on any Interstate motorway in that state. They could have saved far more energy by going about a hundred miles closer to Las Vegas where the tracks are adjacent to the highway and they could use containers shipped by rail to that location. About a hundred miles closer to Salt Lake City is also closer to the tracks. ..HG..
Posted by: Henry Gibson | 25 May 2010 at 01:54 AM
Argon would work but CO2 expands and contracts too much with temperature changes.
Posted by: ai_vin | 25 May 2010 at 01:13 PM
You should check you're tyres regularly anyway to make sure there's no slow punctures etc. I also carry a small compressor that works off the cig lighter.
Personally I run at maximum load pressures (i.e. fully loaded) plus a couple of PSI and it hasn't had any negative effects on handling or wear. The ride's a bit harder but the lower rolling restsiance gives me slightly better mpg. The fronts actually wear better as there's less wear at the edges, which normally cause front tyres to wear-out so quicky.
Posted by: Scott | 29 May 2010 at 06:56 AM