Motorsport Safety
The air gap between layers does more than the fabric does — and the harness squeezes it out precisely where it is needed.
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Protection the suit provides at the incident flux
A whole-suit average is what this computes, and a fire does not average. Protection collapses at every point the suit is compressed — shoulders under the harness, the seat, anywhere the air gap is squeezed out — and those points, not the panel TPP, are where burns occur. The Stoll criterion also assumes a bare skin sensor and no moisture, whereas sweat in the underlayer can carry heat inward and produce a scald injury well before the fabric has failed. Seams, closures, cuffs and the underwear beneath are all outside this calculation and all matter. **This is a decision-support estimate only.** Racewear is certified life-safety equipment under SFI 3.2A or FIA 8856, and only testing of the finished garment establishes compliance.
Racing Suit Thermal Protective Performance & Escape Time — free, with the formula and a worked example, at Textile School.