The "mephitic air" advantage

Automotive Design & Production, Feb, 2003 by Kermit Whitfield

In 1772, Daniel Rutherford discovered something that he called "mephitic air." We now know it as nitrogen. In 2003, David Connaughton has an idea regarding nitrogen. He would like to see every tire in America filled with it. Connaughton is national OEM manager of Parker Hannifin's Filtration and Separation Div. (Cleveland, OH], where, not coincidentally, they make nitrogen inflation systems. Connaughton says that as the pressurized air used to fill tires slowly permeates tire walls and escapes, it not only leads to underinflation, but the oxygen portion of the air reacts with the chemical bonds in the rubber, weakening it and reducing tire life. This can lead to a panoply of bad results, from poor mileage to on-the-road blowouts. Inflating tires with pure nitrogen mitigates many of these problems. It is an inert gas that does not react with rubber, so tires maintain proper pressure longer; and run cooler, minimizing the possibility of blowouts. Connaughton says that tires filled with nitrogen can last up to 2 5% longer, which translates into $100,000 in savings for a truck fleet of 50 with 900 wheel positions.

Fleets are clearly where the immediate opportunities lie for nitrogen inflation, but Connaughton thinks recent concerns about tire safety could translate into car dealerships and gas stations equipped with his machines. The units hook up to existing compressed airlines, don't require potentially dangerous pressurized tanks, and use a membrane technology that requires maintenance only once a year, so the threshold to adoption is pretty low. And there is actually a cool factor. Aircraft and race cars use nitrogen inflation and an increasing number of European motorists are picking up on the practice. Connaughton says, "European drivers put little green stem caps on to show they are using nitrogen. It's becoming a status symbol."