Racing Driver clothing
There are two ways a race driver can get hurt or killed. He can crash or he can burn. . . and a fire is usually preceded by a crash. The driver of a modern race car is fairly well protected from the dangers of crashing-by helmet, seat belt, shoulder harness, and a roll-over structure.
There are two ways he can avoid being burned-either by preventing the fire from happening, or by finding something that will protect him while he's in the fire. Until now, crash protection has been considerably more advanced than fire protection. In the past two years there have been a number of tragic accidents-tragic and grimly ironic -where the driver has survived the crash only to die in the subsequent fire. Unless a fuel can be developed that is non-combustible in the open air (and scientists are already working on that), the fuel has to be contained within the fuel tanks. So tanks can be filled with foam baffling, lined with rubber and coated with fiberglass.
But the danger of fire still exists in big, sturdy stock cars as well as fragile, lightweight sportsiracing cars. If a fire starts, there has been very little anybody could do to provide the driver with adequate protection. Until Nomex.
Nomex is a maverick breed of nylon fiber made by Du Pont. Nylon?
Nylon melts in a fire-doesn't' it?-dripping burning plastic all over the place. Not Nomex. In a fire, Nomex behaves like no nylon you've ever seen before. It will scorch, it will char, and under extremely unlikely conditions, it will burn, but it will also do a better job of protecting a driver from getting hurt in a flaming race car than anything that has been developed up to now.
Actually, Nomex is not as good as an aluminum foil-covered asbestos suit, but you can't wear one of those in a race car for long. You'd pass out from heat prostration (race cars are hot, and foil suits can't breathe). Wrinkle the foil once too often and it starts to crack and peel-and there goes the protection. Foil suits - aside from being prohibitively expensive-are only practical for wearing a few minutes at a time, as in a dragster, and not for 500 miles at Daytona or an hour at Riverside.
There's one more thing. If you are in a fire for longer than 20 seconds half a minute at the most-no suit is going to save you. Sooner or later you have to take a breath. . . and sucking flames into your lungs will kill you. You don't have time to take a deep breath before the fire starts you're probably scared, your metabolism is going like a locomotive anyway, and you're moving around using up energy-frantically trying to get out of the fire. If you're trapped in the fire. . . and if the fire crew doesn't get there and put out the flames within those 20 seconds, you're dead.
Before Nomex, there were two kinds of fire-resistant clothing available to the race driver treated cotton and fiberglass. We might add that not every racing organization makes fire-protective clothing mandatory-otherwise there might have been more. Treated cotton is virtually worthless: it will not support combustion, true, but it by no means provides adequate protection from a fire. For example: at a 2500-degree ambient temperature (typical in a gasoline fire), wearing a treated cotton suit, it takes less than a second to feel pain and about two-and-a-half seconds to blister. With a double layer of Nomex, it takes seven-and-a-half seconds to feel pain and twenty seconds to blister.
Fiberglass looked good for awhile; even to Du Pont engineers trying to prove the superiority of Nomex. They took a dummy; stuffed it into a fiberglass suit, passed it through a flame, and it came out apparently intact. The material was singed, but not burned through (except at the seams). The only trouble was that if a man had been inside the fiberglass suit instead of the dummy, he'd probably have died. It's' an optical illusion, like a baked potato. After it's cooked, its skin looks fine; but open it up and it's all sort of mealy inside. That's a result of thermal conductance. Fiberglass conducts eight times as much heat as Nomex.
When Du Pont engineers exposed a fiberglass-suited dummy to a 2500-degree, high octane gasoline fire, only 2 % of the skin was exposed, versus 12% of the Nomex covered dummy and 17% of the dummy clothed in cotton treated with Borax and boric acid. Then a second series of tests was conducted with thermo-couples attached to the dummy to measure skin temperature. Both dummies wore Nomex underwear, and the weight of the Nomex outer garment was increased from the 3.3-oz.-per-square-yard of the first test to five ounces. Under the same conditions, no skin on either dummy was exposed, but the fiberglass-covered dummy registered a skin temperature of over 600 degrees, while the Nomex-clad dummy's skin reached a temperature of less than 300 degrees equivalent to a painful sunburn. Six hundred degrees will char human flesh.Later, a full-scale series of tests was carried out at the Daytona Speedway. A stock car was sloshed with 15 gallons of Pure Firebird racing gasoline and ignited. A variety of clothing was tried on dummies propped up in the driver's seat, and the fires were allowed to burn for 15, 30 and 60 seconds. The results showed that maximum skin temperatures on the dummy clothed in Nomex underwear and a Nomex coveral1 recorded maximum skin temperatures ranging from 150°F to 440°F. Moreover, in the 60-second burn-to-destruction, the Nomex-protected dummy reached maximum temperatures after 30 seconds, while the fiberglass-suited dummy reached deadly temperatures within the first critical 20 seconds.
Even better results were obtained by first dousing the suit with water. Some stock car drivers do this anyway, to keep cool during a long race, but it also helped keep skin temperatures down in the fire. Incidentally, Du Pont safety experts advise throwing water on a burned driver as soon as the fire is out. His suit may still be smouldering (N omex has no afterglow), and contrary to popular opinion, cold water will both anesthetize and help heal burned tissue.
Wearing Nomex underwear is essential. A single layer of Nomex is no good. The only significant protection is provided by two layers of material. In U.S. Navy tests, "two layers of 3-oz. Nomex remained physically intact after flame contact for over four minutes, whereas a single layer of 6-oz. fabric burned through in 7.5 seconds." In other words, two thin layers of Nomex offer better than 32 times as much flame protection a's a single layer of material twice as thick.
Nomex has many other advantages over existing fire-resistant clothing. Borax/boric acid-treated cotton is uncomfortable-it has low air permeability, it's stiff, scratchy and heavy. It's also not very durable. Permanently "flameproofed" cotton is more comfortable, but offers even less flame protection. Fiberglass is the least comfortable it's hot on hot days and clammy on cold days, it has very low air permeability, it's almost impossible to launder, and most fiberglass suits rarely last more than four races before coming apart at the seams. Fiberglass is also expensive it costs about twice as much as a cotton treated suit. Nomex is light, comfortable, hard to get dirty, easy to clean Nomex has one major disadvantage. It's expensive. A full set of Nomex coveralls and Nomex underwear will sell for close to $75.00. But a roll bar costs more than that, and a good helmet and seat belt cost almost that much. Fire protection is no more expensive than crash protection, but it's just as necessary, and it's a cheap enough price to pay to keep you alive. And there is nothing else that's anywhere near as good. . . at any price.
There are minor disadvantages to knitted from Nomex yarn. Du Pont isn't playing favorites with Nomex-no maker of suits has an exclusive franchise. Du Pont supplies the fibers to the Bibb Manufacturing Company in Macon, Ga., who then sell the fabric to the suit makers. Pegg Smith (2598 Stone Rd., East Point, Ga.), who makes suits for many of the NASCAR drivers, made the prototype suits for Du Pont, and will now make them commercially available. J.B. Hinchman Inc. (546 S. Meridian St., Indianapolis, Ind.), long-time supplier to USAC drivers, will make them. Marion Weber of MG Mitten (P.O. Box 4156, Catalina Station, Pasadena, Calif.) will sell Nomex suits, as will Bob Janssen of Racing Safety Equipment (Box 314, Floral Park, N.Y.), and possibly others. No prices have been set at the present time. Nomex underwear is already available from Sears, Roebuck & Co., for $19.54, but it is not yet known if the suit makers will include the underwear in the price of the outfit or trust the driver to buy it himself. The underwear keeps you cool on a hot day and warm in the winter, regardless of whatever else you're wearing.
Now that there is a truly effective fire-resistant driver's suit available, perhaps it is time to set up fire prevention and protection standards that would apply to all American racing. We already have the basic technology for safe fuel tank construction. We know that race track personnel must get to the fire and put it out within those terrifying 20 seconds. . . or faster. And we have at least one material that will keep the driver alive during that time: Nomex.
