How's this for a marketing campaign? "NitroFlate is an air mixture that contains both small and larger molecules. It virtually eliminates air seepage. It features technology similar to that used in NASCAR race tires. And it is not flammable."
Sound familiar? If you said "NitroFlate" was a new nitrogen tire-fill system, you would be wrong. It's the secret behind the new Spalding Never Flat basketball and soccer ball lines. But the principles are the same as nitrogen tire filling.
There are a lot of frequently asked questions (FAQs) about filling tires with nitrogen. The Get Nitrogen Institute (GNI), a non-profit organization, was formed in 2005 to help answer those questions.
Answering the call
The general purpose of the Denver-based Get Nitrogen Institute (www.getnitrogen.org) is to inform consumers, over-the-road truckers, fleet managers and others about the benefits of using nitrogen in tires. The specific goal is "to save America fuel by maintaining proper tire inflation," according to President Brian Brasch.
Bridgestone Firestone North American Tire LLC, Goodyear Tire & Rubber Co. and Michelin North America Inc. support the use of nitrogen because it helps the tire retain pressure over a longer period of time.
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Here are some frequently asked questions by tire dealers and consumers about the use of nitrogen vs. air in tires. Many of the answers are courtesy of either the Get Nitrogen Institute (which aren't attributed) or Brasch, who is a part owner of Branick Industries Inc. Others come from various nitrogen-fill manufacturers and marketers.
FAQ: Are tires filled with nitrogen maintenance-free?
Answer: No. "Tire pressure still needs to be checked on a regular basis."
FAQ: How much slower does nitrogen leak out of a tire than oxygen?
Answer: "Oxygen leaks out of a tire three to four times faster than nitrogen."
Air Products and Chemicals Inc. further explains that the "permeability of gases is generally faster in some rubbers than in other rubbers, but all rubbers permeate oxygen faster than nitrogen by a ratio of about three to four."
FAQ: Is nitrogen heavier than oxygen?
Answer: No. "Nitrogen molecules are not heavier or denser than oxygen. The truth is the opposite. Nitrogen molecules are, however, larger than oxygen molecules."
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FAQ: Do tires run cooler and last longer with nitrogen than with air/oxygen?
Answer: Indirectly, yes, according to Air Products. "Tire run" temperature is influenced by many factors, including:
* proper inflation,
* rolling resistance,
* road conditions,
* speed,
* outside environment temperature, and
* vehicle load.
"Tire heating will be greater if proper inflation pressure is not maintained," says the company. "Over time, a tire filled with air will lose pressure faster due to faster permeation of oxygen. This will contribute to under-inflation of the tire, absent frequent pressure checks.
"Under-inflation may contribute to excessive mechanical flexing of the tire, which will contribute to additional road resistance and frictional heating. Thus, improper inflation is a principle contributor to excessive tire heating," which affects tire wear.
FAQ: Are there systems that produce 100% nitrogen?
Answer: "Nitrogen tire inflation systems do not produce 100% nitrogen," says Brasch. "Out of a PSA (Pressure Swing Adsorption) system and even a membrane-based system, you can get to 99.99%, but to get it to that purity, it's not cost-efficient."
It may not make economic sense to produce a nitrogen purity level of 99.9% or more, says Ray Schmidt, product engineer for Tire Service Equipment Mfg. Co. Inc. There would be a corresponding increase in capital and operational costs. Schmidt says nitrogen gas generators that use membrane technology are best for purities from 95-98% "with low capital and operational cost." PSA is best for purities from 98% to more than 99% "with higher capital and operational costs." Liquid nitrogen is 99.998% nitrogen.
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"Tires filled with high purity nitrogen will still have residual oxygen in the tire," he says. "There is no cost effective way to eliminate all the oxygen and no benefit to do so."
Parker Hannifin Corp. is familiar with both PSA and membrane technologies. "PSA has moving parts and probably more maintenance requirements than a membrane," says David Connaughton, product sales manager, Nitrogen Generation Systems, for Parker Hannifin. "As moving parts they also require electricity to operate.
"Because of its simplicity, membrane technology is more popular in the automotive aftermarket. And customers are seeing fantastic results in terms of tire life and fuel economy with the purity you can generate with a membrane." "PSA requires no more maintenance than a membrane system, and uses no more electricity than a 30-watt light bulb," says Bob Wolff, vice president of sales for On Site Gas Systems Inc. The company also manufactures both PSA and membrane systems. "With PSA, we are able to generate higher purity nitrogen with less feed air."
FAQ: What percentage of nitrogen is needed to be effective?
Answer: "According to leading tire experts, it's OK to use more than 93-95% nitrogen in your passenger tires, but that's all you need to gain the benefits of nitrogen," says Brasch. "For a truck tire at 100 psi we recommend it’s 97.7%. The higher the pressure in the tire, the higher the purity level has to be.
The goal for tire inflation is to get close to 93%, plus or minus 2%, to get the greatest benefit, says Schmidt, who espouses a slightly lower in-tire percentage than other nitrogen fill manufacturers and marketers. "This is the point at which oxygen molecules under pressure (stabilize) with the outside atmosphere, therefore eliminating further migration of those molecules through the tire wall. A nitrogen gas generator set at 95% will do this."
Jay Lighter, president of Kreska Technologies Inc., sets a higher minimum. "An in-tire purity of no less than 95% is necessary to receive the advertised benefits of nitrogen inflation -- period!"
"The rule of thumb has been a minimum of 95% nitrogen in the tire," says Wolff. "We feel that is accurate because we are involved in many different industries, and 95% will eliminate oxidation; it creates an almost completely inert atmosphere in the tire.
"If the machine produces 95% nitrogen purity, however, you will not end up with 95% in the tire because you are mixing it up with the air already in the tire."
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FAQ: Is nitrogen affected by outside temperatures?
Answer: Yes. "Outside temperature will affect the pressure of a tire filled with nitrogen, but not as much as with regular air. All gases expand and contract to some degree; oxygen expands and contracts very similar to nitrogen.
It is the absence of moisture (with nitrogen) that helps tires to maintain consistent tire pressures."
However, there is no significant difference in expansion and contraction characteristics of nitrogen compared to air when moisture is absent, according to Air Products.
"Expansion or contraction of either air or nitrogen occurs to a very similar extent, in response to changes in temperature, in the commonly encountered range of temperatures and pressures relevant to discussion of tire inflation."
FAQ: How much does it cost to fill tires with nitrogen?
Answer: "The average cost to fill a tire can vary widely, anywhere from $3 to $10 per tire, depending on several variables such as tire size and pressure (larger and higher pressure tires require more nitrogen and longer purge/fill times). In addition to this, many tire dealers choose to bundle nitrogen with other services making the cost per tire higher, while some charge less (or nothing) per tire if you purchase tires from them."
Lighter says it is more of a function of how the procedure is performed than anything else, other than tire size. "High purity, accurate equipment is more expensive to purchase and can require more time, hence requiring a higher selling price. (Lighter, who also owns EF Tire and Auto Repair in Pompano Beach, Fla., typically charges $39.95 to fill four tires, which includes special self-sealing caps and NitroFill Auto Club benefits.)
Costco Wholesale Corp., which sells nitrogen at all its 355 domestic outlets, advertises free nitrogen fill with every tire purchase.
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FAQ: Are tires covered under warranty by the manufacturer if they have nitrogen in them?
Answer: Yes. "Tires are still covered under warranty when nitrogen is used as the inflation medium. Using nitrogen has no effect on the manufacturer's warranty for the tire."
FAQ: Does nitrogen affect the accuracy of a tire pressure monitoring system (TPMS) on some cars?
Answer: "No! Nitrogen as an inflation gas has no affect on the TPMS sensors. The sensors relay compressed air and nitrogen the same. The Tire Pressure Low light should not be on if your tires are properly inflated with nitrogen to the manufacturer's recommended pressure."
Lighter says high purity nitrogen actually creates "the perfect environment" for TPMS sensors because it is an inert (dry) gas. "Additionally, less permeation means less alarms from 'normal' pressure loss."
FAQ: What is the best process for adding nitrogen to my tires?
Answer: "You may simply add nitrogen to a tire already filled with air. However, in order to reap the full benefits of nitrogen tire inflation, you need to achieve the desired level of nitrogen purity and remove any moisture in the tire. To do this it is necessary to purge the tire of the existing air twice, each time down to three psi, and then refill the tire with nitrogen."
Lighter agrees in principle with the process, but still maintains that a minimum of 95% nitrogen fill in the tire -- "as required in military and aviation applications" -- is needed to enjoy the benefits of nitrogen inflation.
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FAQ: Does the use of nitrogen prevent tire aging?
Answer: Yes, yes, and yes. "It's not about nitrogen; it's about reducing oxygen and moisture," according to the GNI. "Oxidation occurs when oxygen reacts at high temperatures and pressures, and it damages inner liners, belt packages and rims.
"Oxygen is also wet, flammable and corrosive."
So there is a "reduced degradation of rubber's mechanical properties" when nitrogen replaces oxygen in a tire, adds Air Products.
The overall conclusion of a 2004 study performed by John Baldwin, David Bauer and Kevin Ellwood of Ford Motor Co. ("Effects of Nitrogen Inflation on Tire Aging and Performance") was as follows;
"When nitrogen is used as the inflation media, the change in rubber properties is significantly slowed down or even halted. From a practical standpoint... the presence of one atmosphere of air in the 96%-inflated tires did not significantly affect the results, as compared to the 99.9% nitrogen-inflated tire."
FAQ: Can air be used in a tire with nitrogen in cases where nitrogen fill service isn't available?
Answer: Topping off nitrogen-filled tires with "plain old air" is no problem. The GNI recommends that your customers use nitrogen in their tires whenever possible, but if they run into a situation where they can't get it, no problem. "Later, you can go back to the tire dealer who inflated your tires with nitrogen for a refill," says the GNI. (And remind them to not forget to have the tire re-purged, adds Lighter.)
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Pressure checks
NitroFlate is referred to by Spalding as a "pressure retention" technology. With the help of "new membrane technology," the basketballs and soccer balls are guaranteed to stay fully inflated for at least one year.
It's important to remember that nitrogen-filled tires cannot guarantee the same thing.
"In a perfect world, I want everybody to check their tire pressure on a monthly basis," says Brasch. "Proper nitrogen fill isn't a substitute, but for the people who don't check it will help them save fuel."
A recent technical bulletin by the Rubber Manufacturers Association sums up the point of view from the tire manufacturers very clearly: "Use of nitrogen alone is not a replacement for regular (tire) inflation pressure maintenance."
Drive safe, not sorry
Driving on properly inflated tires helps everyone drive more safely, says Brian Brasch, president of the Get Nitrogen Institute, citing a 2001 government study.
Based on the study, the National Highway Traffic Safety Administration (NHTSA) estimated that 49 to 79 deaths and up to 10,635 injuries a year could be prevented if vehicles were equipped with tire pressure monitoring systems.
NHTSA estimated 1.5% (660) of all highway fatalities in 2005 were caused by under-inflated tires.
Fuel for thought
The Get Nitrogen Institute features a "Savings Calculator" on its www.getnitrogen.org home page. It calculates monetary savings based on maintaining proper tire pressure.
For example, if:
* the vehicle is driven 13,500 miles annually,
* the tire replacement cost is $100 per tire,
* the average price per gallon of gas is $2.50, and
* the vehicle averages 25 miles per gallon,
the cost savings to the customer will be $98.44 per year. That's $100.07 in Canadian dollars.
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GNI sponsors
The Get Nitrogen Institute (GNI) is sponsored by the following companies:
* Parker Hannifin Corp.
* Branick Industries Inc.
* Champion/Gardner Denver Inc.
* Costco Wholesale Corp.
* Myers Tire Supply Distribution Inc.
* Tire Retread Information Bureau
* Tire Service Equipment Mfg. Co. Inc.
* Ingersoll-Rand Co.
