This story originally appeared in SportsCar magazine's July 2013 issue. SportsCar is the official publication of the Sports Car Club of America. www.scca.com.
The GCR is quite clear on thematter of non-flammable Club Racing driving suites. GCR 9.3.20.C.1, under “Required Equipment,” states: “Driving suits that effectively cover the body from the neck to the ankles and wrists. One-piece suits are highly recommended. All suits shall bear an SFI 3.2A/1 or higher certification label or FIA 1986 Standard or FIA Standard or 8856-2000 homologation label. Underwear of fire-resistant material shall be used, but is optional with suits carrying an FIA Standard 1986 Standard or FIA Standard 8856-2000 label or SFI 3-2A/5 or higher (e.g., /10, /15, /20) certification label.” Clear enough – but how do these suits actually protect you?
Modern non-flammable driving suits are generally made of the Nomex or CarbonX brands, with some suits utilizing a combination of the two – and there are other brands of flame retardant materials out there, too. The debate rages as to which is superior.
Before we go any further, it should be noted that while this story sometimes specifically talks about Nomex, much of the content also applies to other brands of material – and despite the material type, all materials with SFI or FIA ratings succeed at protecting the driver when fire is present.
Most modern driving suits SCCA Club racers will purchase are of the two- or three-layer variety. These layers work together to offer protection from fire. “Race suits are mainly constructed with three layers to provide a well-finished, durable outer layer, a heat-resistant, air-trapping mid layer, and a comfort inner lining layer,” says Nic Sims from race suit maker Alpinestars.
When a flame is applied directly to a Nomex driving suit for an extended period of time, Sims notes that the layers will begin to show signs of carbonization – this is normal. “First, the outer layer will begin to char, discoloring and turning brown,” he says. “If the heat reaches the second layer, the same thing begins to happen. Each layer is designed to provide a barrier as the protection in the layer closest to the source of the heat diminishes, so the suit gives the driver the longest period of protection possible.”
This is one area where CarbonX differs from Nomex. CarbonX protects in a similar fashion to Nomex, but does not discolor in fire due to its construction. According to Chapman Innovations, the maker of CarbonX, the manufacturing process dictates a darker type of material, which is why CarbonX suits and underwear are always dark in color. If you find a bright race suit made of CarbonX, you will likely find the outermost layer is Nomex.
Regardless of the material type, a potential weak point of any driving suit is the zipper and thread. “The zipper absorbs heat at a stable rate and does become a heat conductor,” says Sims, noting that you should buy a race suit that has a protective layer externally and internally around the zipper to prevent heat from the zipper being transferred to the driver's body.
The thread used on the driving suit is also non-flammable. Sims notes that while Nomex suits will use Nomex thread, the thread is still probably the most susceptible part of the suit to fire. “As [Nomex thread] is formed with a relatively thin fiber assembly, it does char faster than the main suit fabric,” he says. To minimize this danger, manufacturers like Alpinestars double stitch their suits with an external and internal line to keep the thread protected.
If you purchase a suit with an SFI 3.2A/5 rating or higher, or it holds an FIA Standard 1986 Standard or FIA Standard 8856-2000 label, non-flammable underwear designed for racing conditions is optional per the GCR – but it's a good idea to wear it regardless. Sims notes that wearing non-flammable race underwear in conjunction with a three-layer driving suit can increase your protection level by upwards of 25 percent, as well as stop other potential risks. Consider this: “Wearing [standard clothes] under the race suit carries the risk of internal combustion next to the skin; while the race suit does not burn, you can trap the burning and heat buildup against the skin,” warns Sims.
Shopping for a driving suit or race underwear? Pg. 54 contains a number of advertisers who can help you with any of your racing suit needs.