A comment was raised in Noah’s last post about protective garments and their effectiveness against fire. I looked into this a bit when I bought my fire suit a few years ago and so I found this site which explains how fire protection is measured. Some of interesting points about these measurements:
- The Specialty Equipment Market Association (SEMA) founded SFI (SEMA Foundation, Inc.) which manages many standards in this area.
- One of these standards is SFI 3.2a which is a specification for how well race car garments resist flame and heat.
- It is based on another standard, Thermal Protective Performance (TPP)
- TPP is a measure of the length of time the garment will protect the wearer from a second degree burn.
The table below, (from the sfi site) lists the SFI, their equivalent TPP value, and the time to burn.
| SFI Rating |
TPP Value |
Time to 2nd Degree Burn |
| 3.2A/1 |
6 |
3 Seconds |
| 3.2A/3 |
14 |
7 Seconds |
| 3.2A/5 |
19 |
10 Seconds |
| 3.2A/10 |
38 |
19 Seconds |
| 3.2A/15 |
60 |
30 Seconds |
| 3.2A/20 |
80 |
40 Seconds |
For comparison the following is a list of required TPP values for different activities:
- Top Fuel Drag Racing: 80
- NASCAR: 38
- NFPA Requirement for Fire Fighting garments: 35
It is interesting to see how little protection these garments actually provide. As a kid I always assumed race car drivers were invulnerable to fire in their suits, but the reality is that a NASCAR driver has 20 seconds before he starts to get burned very badly!
on October 13, 2007 at 8:19 am Sam wrote:
That’s a real eye opener…
on October 13, 2007 at 11:41 am Noah wrote:
I’m actually quite impressed with the performance of these various suits. 20 seconds is a LONG time when you are literally on fire! With the 80 TPP suits, I could get halfway around Lime Rock and still have time for the crews to put me out before burning!
on October 13, 2007 at 11:50 am Sam wrote:
I’m amazed at how little protection a firefighter has compared to a top fuel driver…the firefighter goes into a situation that will likely involve fire, whereas with the driver, a fire is just a possibility.
on October 13, 2007 at 2:20 pm Richard C. wrote:
These suits might protect from the actual burn for 40 seconds, but what about just “baking” inside the suit? I can’t imagine being on fire for 40 seconds is very comfortable, especially inside those helmets. Much after 40 seconds does it probably get to the point where the suit outlasts the person?
on October 13, 2007 at 2:21 pm Henry wrote:
No Richard, the measurement includes damage from heat. The 40 seconds or whatever you get is 40 seconds until burn from heat or exposure to fire.
– Henry