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Nitrogen inflation

NAPIERVILLE, Que. - Not long after beginning the transition to inflating tires with nitrogen in May 2006, Gilles Guillard, fleet manager with Normandin Transit in Napierville, Quebec, began receiving ...

A FUTURE STANDARD?: This nitrogen generator, the TireSaver by Parker, has made a believer out of one Quebec fleet manager.

A FUTURE STANDARD?: This nitrogen generator, the TireSaver by Parker, has made a believer out of one Quebec fleet manager.

NAPIERVILLE, Que. – Not long after beginning the transition to inflating tires with nitrogen in May 2006, Gilles Guillard, fleet manager with Normandin Transit in Napierville, Quebec, began receiving inflation test results that showed hardly any loss of tire pressure in the nitrogen-filled tires.

The result was a radical shift in the yard’s inflation management schedule, and provided considerable savings in tire inflation maintenance.

“Before, with air, (we) did inflation checks before every trip. Now an inflation inspection is done on the nitrogen-filled tires every three months. There is no more need to have someone driving around the yard checking tire pressures,” says Guillard.

Guillard had heard of the advantages of nitrogen inflation even before he moved to Canada from France nearly 25 years ago. A friend’s trucking company was experiencing tire failures, which were greatly reduced after switching to nitrogen inflation.

“In France, it has been used for 23 years, but I had never seen it here,” he recalls. As soon as machines became available that had sufficient capacity to serve the Normandin fleet, however, the company bought in.

Normandin purchased a Parker TireSaver nitrogen generator, which tucks neatly into a corner of the shop and ran dedicated nitrogen lines to each repair bay. Normandin also installed a system that can change five tires from air to nitrogen at a time. The total set-up cost was $20,000.

The wholesale transfer to nitrogen-inflated tires began with dropdeck trailers and the smaller trucks.

“The tires on them blew frequently,” Guillard recalls. The change from air involves purging each tire twice with nitrogen before the final nitrogen inflation. The company runs 246 tractors and 500 trailers.

Since switching to nitrogen the company has experienced far fewer blowouts and has measured less tread wear. The reduction in blowouts has been at least 15%.

“Repairs on the road have decreased by 15%, minimum,” says Guillard, who adds that the cost of replacing one tire on the road in the United States can run to $700 or even $800. Consulting his notes, Guillard reports that tire wear in air-filled tires was running at 1/32-inch every 42,000 to 46,000 km. With nitrogen however, he has been getting from 51,000 to 55,000 km per 1/32-inch, and the wear is more even around the tires.

There are two little traps for converts to nitrogen, according to Guillard: It is a bad idea to run duals with one air-filled tire and one filled with nitrogen, since the oxygen-filled tire will expand more, causing abnormal wear in the nitrogen-filled tire. There is also the inconvenience of tire repair trucks not carrying nitrogen, which means that for on-the-road repairs, air is the only option. (Note: Parker does sell mobile nitrogen inflation systems for service trucks, so if the demand for nitrogen grows sufficiently, repair vehicles will surely start to carry nitrogen.)

Guillard has not noticed improved fuel consumption, but this he attributes to having had a good tire inflation program, which prevented underinflation and increased rolling resistance.

“A fleet that does not keep proper tire pressures would notice a difference in fuel consumption. But a fleet that maintained good tire pressures with air would not see a significant improvement in fuel consumption once having switched to nitrogen,” he says.

It is too early to tell if the casing quality of the fleets’ tires will be better under the nitrogen regime. Guillard expects that there will be less contamination of the rubber (proponents of nitrogen inflation say that rubber degradation and tire cord rusting are non-issues with nitrogen). Normally he recaps the tire once for the trailers and twice for the power axles on the tractor. Guillard hopes to get twice as many recaps with the nitrogen-filled tires.

He has no before-and-after comparisons of tire temperatures. But his drivers claim they notice a difference in tire pressures in the hot states.

The literature and tire manufacturers’ recommendations on nitrogen use will lead the dispassionate researcher around in circles: the arguments for and against can both sound compelling, and there are articles out there that play fast and loose with the available evidence.

Theorizing about nitrogen’s possible advantages is healthy enough, but by their nature, theories are never conclusive. For example, one fleet manager in Western Canada reasons that there couldn’t possibly be an advantage to using nitrogen (the generators produce about 95% pure nitrogen), since air is already about 78% nitrogen.

Yet the increase is noticeable enough for tire manufacturers like Michelin to recommend its use in aircraft and racing cars, where abnormal overheating of tires and wheel assemblies could occur.

In practice, there are fleets that have switched that are reporting good results. (Are there any fleets out there that have switched to nitrogen, but noticed no improvements in tire wear, fuel consumption or more stable tire pressures?)

The Drexan Corporation, in Burnaby, British Columbia, which distributes nitrogen generators, invested a sizeable sum, with contributing funds from Transport Canada’s Freight Sustainability Demonstration Program, to conduct a study last year on the effects of nitrogen inflation on fuel economy and tread life benefits.

Over a nine-month period running nitrogen-filled tires with Winnipeg-based Harris Transport, over 1,988 wheel positions and many millions of kilometres of travel, Drexan reported 6.1% better fuel efficiency over air with no pressure maintenance program, and a 3.3% improvement in fuel economy over air with a pressure maintenance program. Tread wear for the nitrogen-filled tires was reportedly 86% less than with air-filled tires operated under a pressure maintenance program. There are many other details reported in the study, which Drexan expects to publish in an upcoming paper.

The controversy over the merits of nitrogen inflation for over-the-road fleets will rage on, but as more fleets that have switched relate their experiences, and more interested parties like Drexan put their money where their mouths are to conduct more rigorous studies, fleets should be able to, with more confidence, decide whether to switch or not.

In Napierville however, Guillard, whose mind has been long made up, simply says, “Nitrogen is the future.”

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