Tech Tips: All Driver's Suits Are Not Created Equal - Unraveling the SFI Rating Mystery

Most sanctioning bodies require, at a minimum, an SFI rated drivers suit, or at least the regulation may have language somewhat like this: "A one-piece fire retardant driving suit is required. (Two layer or one layer plus fire retardant underwear minimum - two or three layer suits meeting specifications of SFI 3.2A/5 or FIA 8856-2018 are strongly recommended.)" What exactly does this SFI and FIA stuff mean anyway?

There are two materials that are used extensively in the manufacture of driving suits, Proban and Nomex. Proban is a cotton-based material that has been chemically treated to make it fire retardant. This treatment may diminish with washing. It is used primarily in single layer economy suits although there has been a disturbing increase in manufacturers using it to manufacture inexpensive multi-layer suits.

Nomex is a permanently fire retardant Aramid fiber that is manufactured by DuPont. It is woven or knitted into material by one of several mills in the U.S. Since it is inherently fire retardant its protection does not diminish with time or washing.

The Proban suit may initially look like a bargain but the life span of the Nomex suit often doubles or triples that of Proban with proper care. Worse yet, it is impossible to tell when Proban may have lost some or all of its ability to protect the wearer in a fire. Northstar Motorsports strongly recommends that all Nomex driving suits be dry cleaned rather than machine or hand washed. This is in accordance with most manufacturers recommendations.

That is why Northstar Motorsports only sells multi-layer suits made from Nomex, and we highly recommend either a three-layer suit with an FIA 8856-2018 rating or a two or three layer suit with either and FIA or an SFI 3.2A/5 rating for all types of racing. Northstar also carries single-layer Nomex suits which we recommend for use only as "over-the-wall crew suits". Even in those applications it is still very wise to wear Nomex underwear under these single-layer suits. All current FIA approved suits rated FIA 8856-2018 have an expiration date embroidered on the suit.

The SFI Foundation is a non-profit organization established to issue and administer standards for specialty/performance automotive and racing equipment. SFI tests a long list of products including gloves, head and neck restraints, suits, shoes, restraint systems, underwear, window nets and roll-bar padding to name a few.

The SFI standards program is funded by participating manufacturers paying for development and administration through licensing and/or unit charges. The SFI specification for driver's suits, Spec 3.2A, rates how long a driving suit will offer protection from second-degree burns in an approximation of a raging gasoline inferno between 1800 and 2100 degrees. SFI ratings are calculated in calories per unit, area per time of exposure. Basically, it gives the buyer a rating system to judge any suit relative protection capabilities. The following table give an approximate time until second-degree burns will occur based on the SFI rating of the driver's suit: