Fire: A Motorsports Safety Challenge

While NASCAR has made significant advances in protecting drivers from crashes, protecting them from fire is a much different — and much more scientifically challenging — problem. I was reminded of that by how Ryan Blaney’s night ended at the Coca Cola 600.

Fire Safety and Racecars: A Brief History

There is no way to eliminate the possibility of fire in motorsports.

A loaded NASCAR race car carries 22 gallons of fuel and more than a gallon of oil, all in close proximity to very hot pieces of metal and electrical equipment. Parts and pieces are pushed to their limits, which increases the probability of failure. A broken part can easily disconnect or rupture a fuel or oil line, spreading the flammable liquid.

Fireball1 Roberts’ death after a fiery wreck2 in the 1964 World 600 spawned NASCAR’s first fire safety rules.

  • Fire-resistant driver safety gear was mandated. Drivers used to dip street clothes in fire-retardant chemicals. Roberts was an asthmatic and the chemicals used worsened his symptom, so he didn’t use the chemicals. Drivers were now required to wear actual firesuits.
  • On-board fire-extinguishers were required in the cockpit, within reach of the driver
  • Steel fuel tanks, which could easily rupture in a crash, were replaced by rubber fuel cells, which offer better containment.

The driver’s best protection against fire is getting out of the car; however, that’s not always possible. NASCAR firesuits protect against second degree burns for about 10 seconds. If a car bursts into flame while going 200 mph, it could take more than ten seconds for the driver to slow the car down and steer it to a place where it’s safe to get out of the car.

In the case of a crash, the driver’s ability to steer may be compromised. In Dale Earnhardt, Jr.’s 2014 Texas crash, the car stopped with the driver’s side jammed up against the outside wall. Dale had to wriggle out of the car and walk across the car’s hood to get away from the vehicle.

Ironically, many of the safety improvements that guard drivers against impacts make it harder for the driver to get out of the car quickly: wrap-around seats, HANS devices, helmets, gloves, etc.

The first on-board fire fighting systems were basically giving the driver ready access to a fire extinguisher. These early systems used portable dry powder extinguishers. The driver had to locate the fire extinguisher, aim it and pull the pin. If  the driver was successful in doing so, he found himself inside a smoke- and powder-filled racecar. The chemical powder used to smother the fire was extremely hard on human lungs. Most drivers felt that getting out and letting someone else handling putting out the fire was the way to go.

And this system didn’t address the absolute worst case: a driver who is knocked unconscious, injured enough to not be able to get out of the car, or pinned in the car.

Taking It Out of the Drivers’ Hands

A.J. Foyt’s team debuted the first automatic onboard fire extinguishing system debuted in the 1967 Indy 500. After Foyt had a fiery crash in Milwaukee in  1965, DuPont representatives offered help designing an integral fire extinguisher system.

The extinguisher was fixed to the car, with a manual valve the driver could open, plus a temperate-sensitive switch that would automatically deploy if needed.  (Incidentally, in 1975, Foyt was accused by Indy500 competitors of hiding extra fuel in his fire extinguisher.)

NASCAR Today

The driver’s cockpit has a volume of about 100 cubic feet. NASCAR requires a 5-lb manually-activated fire extinguisher. The locations of the nozzle and the switch are shown in the drawing below.

When Ryan Blaney was asked if he had activated the fire suppression system, his response was:

“Dude, I was trying to get out of it. I didn’t look for the pin. I couldn’t see it regardless. –Ryan Blaney”

This frames the problem nicely: You don’t want the cockpit system to be automatic because you can envision times you don’t want it going off, but if the system isn’t such that the driver can deploy it without effort, it’s not likely to be used.

In 2003, NASCAR required a separate, thermally activated fire extinguisher system for the fuel-cell area. This system contains 10 pounds of extinguishing chemical for the 17 cubic foot fuel cell compartment (which can contain up to 22 gallons of fuel).

But even this system isn’t sufficient for all situations.

Putting Out Fires

Before you can talk about ways to stop fire, you have to understand what causes fire. A fire requires three components:

  • Heat
  • Oxygen
  • Fuel

Once you have these three components, fire continues via a chain reaction.

Liquids and solids aren’t flammable, per se. They have to be heated to a point where their atoms form a flammable vapor. When gasoline catches on fire, it’s not liquid gas that’s burning. It’s gasoline vapor atoms.

Heat causes a fuel to produce vapors of free radicals — highly reactive compounds that quickly combine with oxygen from the air. That combustion reaction produces more heat. That heat frees more free radicals from the fuel, which combine with oxygen and produce more heat. It’s like a nuclear chair reaction, but it’s a molecular-level phenomenon, not a nuclear-level phenomenon.

Putting out a fire requires you to either

  • eliminate one of the three elements

OR

  • stop the chain reaction.

How Water Puts Out Fire

Water cools a fire, eliminating the component ‘heat’.

It takes heat to turn water from liquid to steam. Water redirects the fire’s heat into vaporizing the water, which decreases the overall heat available to form more free radicals.

A secondary effect is that a thin layer of water is formed between the burning materials and the air around the materials. That layer separates the fire and the fuel.

Gasoline Fires

Water works great on fires caused by Class A Combustibles: ordinary materials such as paper and wood, clothing, rubber, plastics, etc. Other types of fire call for different approaches.

Class B Combustibles are flammable liquids and gases like gasoline, paint thinner, propane, etc. These liquids float on water because oil (and gasoline and many greases) are less dense than water and do not mix with water. Water won’t work on a grease fire because:

  • The water cannot form a protective barrier between the fuel and the air because the fuel will float to the top of the water
  • A stream of water can cause the oil to spatter, which distributes the fuel over a wider area and primes that area for fire.

Carbon Dioxide Fire Extinguishers

One way to put out a gasoline or other grease fire is to use chemicals that remove or displace oxygen. Carbon dioxide (aka CO2), for example, turns to foam when you spray it under pressure. CO2 is heavier than air, so it displaces the air around the fuel. The foam covers the fuel and forms a barrier against oxygen. A pressurized liquid that is released also come out cold, so there is some heat mitigation as well.

But there’s a major problem with CO2 extinguishers for race cars. Drivers breathe oxygen. If the extinguisher displaces most of the oxygen, the driver has a problem. Carbon dioxide extinguishers should never be used in confined spaces.

Dry Chemical

These were the first fire extinguishers used in motorsports and there are good reasons why they aren’t used anymore. The dry chemicals used are ususally monoammonium phosphate (also used as fertilizer), sodium bicarbonate (yes, baking soda) and potassium bicarbonate (which, for you fire aficionados, is also the main ingredient in Purple-K). They create a barrier between the oxygen and the fuel.

They are often more effective than carbon dioxide extinguishers, but the risks outweigh the benefits when it comes to motorsports . You have to worry about the driver getting the powder in his or her eyes (which could be a safety hazard if the driver is still piloting the car to a safe spot), the driver breathes in the chemicals, and they are hard to clean up.

So What Does Work?

Halon

The first onboard fire extinguishing system, as I mentioned, was that of A.J. Foyt in 1967. It used Halon 1301 (CBrF3). Halon is a chlorofluorocarbon gas that can be liquified and stored in a pressurized bottle, which means you can store a lot of gas in a small amount of space. When it is deployed, the gas covers the entire volume, providing three-dimensional protection that doesn’t requiring any aiming.

Halons were first used in World War 2 on aircraft and tanks (which are always good comparators for racecars). They didn’t impair the driver’s vision and, because Halon doesn’t form conductive ions, it doesn’t damage electronics. While driver safety is obviously most important, you’d like a fire supression agent that doesn’t damage the racecar.

There was a problem with Halon 1311, though. It often became very warm during races and discharged without warning. A variant (Halon 1211) was found to be preferable because it didn’t need to be held at such high pressure, which means it didn’t discharge accidentally.

Halon 1211 is the brand name for bromochlorodifluoromethane , or CF2ClBr. Extensive testing (by the Mike Sorokin Safety Foundation and DuPont) is developed the five-pound rule in force at many race tracks: 5 lbs of of an approved extinguishing gas is required in the cockpit.

Halon does cool the fuel somewhat, but its primary fire suppression mechanism is due to chemical interactions with the combustion products. The molecule breaks up and the bromine and chlorine ions attach to the free radicals before the free radicals can combust with oxygen. This breaks up the chain reaction.

Halon has a lot of advantages. Because it doesn’t displace oxygen, there is no problem using it in a confined space. It’s stable and easily recyclable and was used for years in race cars. It does, however, have two big problems that weren’t realized until the 1990’s.

You may have noticed the word chlorofluorocarbon in my description of Halons and therein lies the first problem. Halon is a CFC, which means it destroys the ozone layer. In fact, Halon is also knows as Freon 12B1. CFCs were banned from production in 1994 as part of the Montreal Protocol. They can still be used, but the fact that there’s a limited supply means that they are very expensive.

But there’s an even bigger problem with Halon. Remember when ‘huffing’ was a thing? People would spray CFCs in a bag an inhale the fumes to get high. A lot of people died doing that because it turns out that CFC fumes cause cardiac sensitization and arrhythmia — which can lean to  death.

So even if Halon hadn’t been legislated away because of environmental concerns, motorsports would have stopped using it because of the potential danger to drivers.

The New Fire Fighters

When it became clear Halon’s days were numbered, the SFI Foundation developed a standard for fire suppression systems (SFI 17.1), which considers not only the efficiency of an agent in putting out a fire, but driver impact.

Note that this wasn’t just a motorsports problem. Halons were the global industry standard for fire protection. DuPont, as a chemical supplier and an active motorsports supporter, took the lead to find alternatives. As with any motorsports application, you end up with a long list of requirements.

  • Effective at suppressing fire
  • Acceptable human inhalation toxicity
  • Does not impair or obstruct the driver or rescue team
  • Ability to suppress a fire that is shielded behind something
  • Easy to use
  • Easy to clean up
  • No residue that would affect subsequent track grip
  • Electrically nonconductive
  • Small and light
  • Shelf stable

Simple, right?

DuPont came up with two alternatives

FE-36

FE-36 is a hydrofluorocarbon: 1,1,1,3,3,3-Hexafluoropropane or CF3CH2CF3. Hydrofluorocarbons are similar to chlorofluorocarbons, but since hydrofluorocarbons have neither bromine nor chlorine atoms, they are not damaging to the ozone layer. They aren’t quite as effective as the Halons, but they do the job and don’t have the cardiac sensitization issues of the chlorofluorocarbons. FE-36 became the prime ingredient in motorsports fire suppression  systems, allow use of Halon to be phased out.

FM-200

DuPont also created the FM-200 fire suppressant which is 1,1,1,2,3,3,3-heptafluoropropane (CF3CHFCF3) and similar to FE-36. They’re in the same family. This one is marketed more for protecting computer rooms, data control centers and museums, but it’s also SFI approved.

But…

The objection to Halon was its high ozone depleting potential (ODP), but as we started to understand that there was more to the environment than the ozone layer, we had to look at other aspects of these materials. Hydrofluorocarbons are still greenhouse gases. Again, the use in motorsports is tiny, but the use of these materials worldwide across all industries is not.

FE-36 has an atmospheric lifetime of 220 years. That means that if a FE-36 fire protection unit goes off during a race, those molecules will be hanging around our atmosphere until 2238. FM-200 is a little better because its atmospheric lifetime is only 33 years, but that’s still a pretty long time.

Because of these concerns, legislation to regulate and eventually phase-out the use of these chemicals is being considered (mostly in the European Union at present).  Chemical manufacturers have gone back to the drawing board.

NOVEC 1230

In 2012, a NOVEC-1230 fire suppression system was debuted on Greg Biffle’s #16 car. NOVEC 1230 was created by 3M, then Biffle’s sponsor. I would love to be the person who thinks up brand names for things. You must admit that “NOVEC” is much catchier than CF3CF2C(O)CF(CF3)2 – or dodecafluoro-2-methylpentan-3-one.

Novec 1230 works by absorbing heat. It’s the same mechanism water uses, but Novec is a little more complicated. When released, Novec 1230 combines with air to form a gas capable of absorbing a lot of heat. It also evaporates 50 times faster than water.

Novec 1230 offers similar no-ozone-depletion, but creates much less of a greenhouse gas load. The atmospheric lifetime of Novec 1230 is five days (compared to 220 years of FE-36). Novec 1230 shows a lot of promise for the biggest fire-protection issue these days: protecting data centers where huge numbers of hot-running servers store people’s critical data.

No Solution is Perfect

Even if you satisfy all of the criteria I listed above, there is still the reality that it really isn’t that hard to envision a situation in which fire causes a serious injury or death. Let’s not forget that incident aren’t limited to the racecar. In the Richmond XFINITY race in 2015, a number of crew members were injured when a spark from a car leaving Pit Road ignited fuel. A series of pit-road accidents lead F1 to prohibit cars from refueling during races in 2010. While it adds an interesting variational element for F1 (the car’s handling changes greatly as the fuel load goes from 100 pounds toward zero), it’s unrealistic for NASCAR.

As we’ve said here before: There is no way to make racing entirely safe.

Notes

  1. Fireball Roberts got his nickname from his baseball career, not as a result of the accident that ultimately led to his death.
  2. Roberts emerged from the crash with burns over 80% of his body and miraculously survived for several weeks, but ultimately contracted pneumonia and sepsis.

For More on this Topic:

Fired Up – The Science of Flames

Myths about Fire and Racing

 

 

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Also published on Medium.

3 thoughts on “Fire: A Motorsports Safety Challenge”

  1. “There is no way to eliminate the possibility of fire in motorsports.” Never has a truer word been spoken.

    If we enjoy motorsport, we have to accept that there are risks, just like anything in life. And given the speeds achieved, it’s actually amazing how little incidents there are, really.

  2. Ugh. As someone who worked around datacenters, HALON systems and their successors are just as bad, if not worse, at displacing oxygen as CO2. I’d personally rather have a CO2 system, as it’s guaranteed to be non-toxic, and it’s a normal atmospheric compound. You may not be able to stop within 10 seconds, but you can generally deal with holding your breath for more than 30 seconds.
    (2nd post due to SSL failure)

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