Car Fire Extinguisher - Flame Out

Corvettes & Fire Don't Mix

Wayne Scraba May 28, 2008 0 Comment(s)

Fire and Corvettes simply do not mix. A small fire in a conventional steel-bodied car is one thing (and usually repairable), but a fire in a Corvette usually spells "catastrophe." Of course, the old "it can't happen to me" syndrome usually strikes, but just for the sake of discussion, pretend you're cruising down Main Street with your pristine '67 427-powered coupe. What happens if a nut on the fuel line inadvertently backs off, or a mechanical fuel pump fails, or a needle and seat assembly sticks and gasoline is sprayed onto a set of hot exhaust manifolds? How much time will it take for you to (A) figure out there is a real problem and (B) stop and do something about it. We suspect it will take longer than you'd like in both cases.

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What Can You Do About It?
there are preventative measures you can take. A fire extinguishing system is the ultimate solution. Believe it or not, it is possible to purchase a capable and comprehensive extinguishing system for under $500. And for less than $750, you can have something with all the bells and whistles. In contrast, you have to consider how much you'll lose if you inadvertently torch the car. Insurance will cover you, right? Maybe. Maybe not. Let's imagine you have $50,000 (or more) tied up in a '67 Corvette. Will the insurance company view your car as a beautifully restored vintage Vette or will they look at it as just another old car? One way or another, there's a good chance you could get burned.

Several insurance companies offer deep discounts if a classic vehicle is equipped with a dedicated on-board fire fighting system. In some cases, these discounts may be significant enough to cover the cost of the on-board fire fighting equipment in the first year or two.

How Difficult Is It To Install A Complete On-Board Fire System?
The systems aren't complex. On the activation side of the equation, you can get anything from a simple pull cable release to a system that takes its activation from the air shifter (CO2) bottle. In between are systems that use either a push or a pull knob. If you can hook up a throttle cable, you can install a system such as this. As far as the discharge is concerned, some of the more complex fire fighting systems use multiple discharge nozzles. The hook up is by way of an AN fitting. All that's required is to cut, bend, and flare either a steel or aluminum hard line so that it can be affixed to a remote discharge outlet (more on this later). Mounting of the bottle is equally easy. Typically, an aluminum bracket is affixed to some point in the car, and the bottle is clamped to the bracket by way of aircraft-style clamps.

How Big Is This Stuff?
Complete systems are not as complex and heavy as you might think. The most sophisticated, highest capacity system tips the scales at 1611/42 pounds (charged). Bottles generally don't exceed 20-inches overall (including discharge head) and usually have a maximum diameter under 7 inches. You can get a lightweight system that weighs in the range of 6 pounds. DOT-approved, high-pressure, carbon-fiber bottles are also available.

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Top Gun
This is Safecraft's top-of-the-line system. It's a model RS from Safecraft. This is a 10-pound system that is commonly used in pro-racing applications. The bottle is a DOT-approved aluminum model, while the head is a pneumatic model.

One Size Doesn't Really Fit All
So what's out there? You have plenty of choices. In the Safecraft line, here's a rundown of the system features, starting with the most comprehensive package (from a cost and function perspective).

This particular extinguisher is capable of accepting up to three separate discharge lines. This means you can run a line to the engine compartment, one to the area of the fuel cell, and another in the cockpit. The extinguishers are available in 2-, 3-, 5-, 10- and 20-pound Halon capacity with other EPA/SNAP agents available as well. All extinguishers are available in brushed or polished finish. You can also specify bottles manufactured from carbon fiber. The discharge heads are billet aluminum and are anodized red. A unique feature of the RS is the swivel head. You simply loosen two setscrews at the base of the head, and it can be oriented to suit the application. Mounting brackets are aluminum. Several different head options are available.

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Bottle Size
Several different bottle sizes are available, including a 10-pound model, 5-pound model, and even 3-pound models. All can be configured with basic pull-cable-style single discharge heads. Optionally available are push-knob activation, dual-discharge heads along with a pneumatic dual discharge head. these extinguishers are available in 3-, 5- and 10-pound halon capacity with other EPA/SNAP agents available.

LT Models
The RaceSafe LT fire extinguisher by Safecraft is a new lightweight design that is almost a pound lighter than other models they offer. It makes use of a compact discharge head, which translates into a smaller overall package. A neat feature is the swivel head. This means the discharge head can be rotated to align the pull cable, which, obviously, provides flexibility when it comes to the installation. This feature is different than that found on the RS Models. In this case, you loosen a setscrew near the top and the head swivels where the pull cable is affixed (the discharge ports are stationary). The aluminum cylinder is U.S. DOT approved and is capable of being refilled. Like the top of the line RS, the discharge head on this model is machined from billet aluminum and is pull-cable actuated. The extinguisher will accept two separate discharge lines (typically, one in the engine compartment and one in the passenger compartment). The LT model extinguishers are available in 3-, 5- and 10-pound Halon capacity with other EPA/SNAP agents available as well. All three sizes come standard with a white powdercoated cylinder along with a brushed-aluminum anodized head. Complete installation and mounting kits, based upon your application, are available.

LS Model
Safecraft's Model LS is a compact assembly that combines ingredients of the previously described LT and RS models. The Model LS uses an aluminum high-pressure cylinder that is U.S. and Canadian DOT approved and is capable of being refilled by an authorized distributor. The discharge head is machined from billet aluminum and is actuated by pull cable. The extinguisher is capable of being set up with two separate discharge lines (much like the model LT). The extinguishers in this line are available in brushed or polished finish. The LS examples are available in 5-pound Halon 1211 capacity only. Different plumbing and installation kits are available, again to suit your application.

For Comparison's Sake
The chart below shows a comparison of features between several of the above models (note that all possible configurations are not listed).

Fire Extinguishing Agents
What about the actual fire extinguishing agents? You might be surprised to find out what really is available.

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HeadsBoth the pneumatic and cable activated heads for RS systems can use three separate discharge ports. Each is an AN male port, and they're designed to be hooked up to billet discharge nozzles placed in the location of your choice. Typically, one nozzle is placed in the engine compartment, another in the driver's compartment, and a third in the area of the fuel cell.

Halon
Halons are low-toxicity, chemically-stable compounds that have been used for fire and explosion protection from the turn of the last century. Carbon tetrachloride (Halon 104) was used prior to 1900, but there was a catch: The combustion by-products were deadly. Given the number of fatalities caused by the combustion by-products, other compounds (including other halons) were tried. In 1947, investigation by the Purdue Research Foundation and the U.S. Army resulted in the discovery of two effective, low toxicity halons: 1211 and 1301. When used properly, these halons have an excellent fire fighting record with little, if any, risk. Today, Halon 1211 (defined as a liquid streaming agent) is used primarily in hand-held fire extinguishers. Meanwhile, Halon 1301 (defined as a gaseous agent) is used primarily in total flooding systems. These halons have proven to be extremely effective fire suppressants, which are clean (leave no residue), colorless, odorless, electrically nonconductive, and prove to be remarkably safe for human exposure.

A halon blend (or 1301) is far superior to the 1211 Halon propelled by nitrogen because it generates its own pressure-performance does not degrade significantly as the extinguisher is emptied. Extensive toxicity evaluations have been compiled on Halon 1301 and 1211. These evaluations have consistently shown that Halon 1301 is the safest extinguishing agent available (although not safer than pure water), and that Halon 1211 is the second safest. Halon concentrations of about 5 percent by volume in air are adequate to extinguish fires of most combustible materials.

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Nozzles
When it comes to nozzle plumbing, the hardline can either be steel or aluminum. You simply cut and flare the tubing to mate to the AN fittings and you're done. Note that the discharge nozzles are designed so that each has three outlets. This means a fan spray of sorts is used to spread the fire-extinguishing agent. Keep this in mind when mounting the nozzles. And also keep in mind that the compressed agent can be dry ice cold. As a result, careful placement in the interior is rather important (don't aim it directly at you or your passenger).

How do they work?

According to the experts, three things must take place simultaneously to start a fire. The first ingredient is fuel (anything that can burn), the second is oxygen (sufficient air for human breathing is ample), and the last is an ignition source (high heat can cause a fire even if there is no spark or open flame). In order to stop the fire you need to remove one ingredient in the mix-the ignition source, the fuel source, or the oxygen source. Halon is so effective because it adds a fourth dimension to fighting the fire-it breaks the chain reaction. It works this way by stopping the fuel source, ignition source, and oxygen source from working together by way of chemical reaction. The most common extinguishing agents, such as water, carbon dioxide, dry chemical, and foams attack the fire physically, depriving the fire of one or more of the three critical elements needed for propagation. Halon differs from all other extinguishing agents in the way it puts out the fire. It offers some of water's cooling effect and some of carbon dioxide's smothering action, but the essential extinguishing methodology lies in its capacity to chemically react with the components of the fire.

A common fallacy about halon is that it displaces the air from the area it's dispensed into. That's absolutely incorrect. According to folks in the know, even for the toughest fire, less than an 8-percent concentration by volume is necessary. This means there is still plenty of air to use in the evacuation process.

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Pull Cable
Pull cable release discharge heads use this mechanism. One or two separate cables can activate the head. The idea here is to make one cable easily accessible to the driver, while the other cable can be mounted so that it's easily accessed by someone else (for example, the passenger). The handle end of the cable is just like this. It's equipped with a safety pin. Obviously, the idea is to pull the safety pin before you race, then re-install it when the car is in the pits. Mounting of the cable is relatively simple. Some folks mount the handle right in the dash, while others simply build a bracket to hold it in place. Just remember to keep the handle in a spot that's accessible when you're belted in the car.

Where Is Halon Used?
Over time, the largest single user of halon has been the electronics industry. Approximately 65 percent of all Halon 1301 in use is employed for the protection of electronics facilities (e.g., computer banks, communications facilities, and so on). The U.S. Government uses halon for a number of military applications (in ships, aircraft, and land-based vehicles such as tanks). Commercial aircraft also use halons extensively (e.g., each engine nacelle in a Boeing jet is protected by halon). Halons are used extensively in oil production, electric power generation, and are actually required on most commercial passenger aircraft (in cargo and passenger compartments as well as in engine nacelles).

What about Halon and the Ozone Layer?
The ability of a compound to destroy ozone depends upon a number of factors, including the amount of chlorine and/or bromine contained within, along with their chemical stability. In order to compare various compounds, scientists have developed a relative scale called the Ozone Depletion Potential (ODP). For example, common refrigerants, like those found in older refrigerators and in the air conditioner of an older car, have been assigned the value of "1." Halon 1301 has an assigned value between 10 and 16, which means it has 10-16 times greater potential for destroying the ozone layer. Halons can definitely carve up the ozone layer. That's a given, but there is also a catch. Halon use worldwide is significantly less than that of CFCs. Even though it is much more damaging to the ozone layer, there is simply not as much of it released into the atmosphere. It is estimated that overall, halons account for less than 1 percent of the ozone depletion.

When the environmental effects of halon became known, industrial users of halon and people from the fire protection industry worked in unison to limit the use of halons and helped to institute tight restrictions on halon emissions. Through changes in standards and specifications, the industry has virtually eliminated its use of halon for testing and training purposes. In truth, testing and training had been responsible for the bulk of halon emissions. Many organizations (governments, businesses, and so on) that continue to rely upon halon systems for fire protection have introduced programs where the most critical need is addressed. This way, halons that can be removed from noncritical or obsolete facilities are then recovered for use in more critical applications. This brings about a practice called halon recycling.

Recycled Halon
There is a rule (administered by the EPA) that establishes that halon itself must be properly disposed of. Proper disposal means only halon recycling by a facility or destruction using one of several controlled processes identified in the regulation.

Once halon is released into the atmosphere, it is virtually impossible to recover. If halon is still contained in cylinders retired from service or if a container is leaking, the halon can be recovered for reuse. In fact, some halon distributors and users have been doing this for many years, long before halon emissions were identified as an environmental problem. Current legislation prohibits the production or importation of new Halon 1211, 1301, or 2402 into the U.S. As a result, recycled halon is now the only source of supply.

It can be obtained from a number of sources, including fire equipment distributors and independent recyclers. A non-profit organization has been formed to assist in halon recycling. The Halon Recycling Corporation (HRC) acts as a facilitating organization by providing information services to match companies with a surplus of halon with those companies who have an ongoing need for the fire-fighting agent.

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Mountings
Mounting of the bottles is simple. There are a couple of different mount arrangements used. Generally, the type of system dictates the mount style. For example, the RS system shown in this photo is based upon a pair of aircraft "T" bolt mounting clamps that grasp the bottle. In turn, the clamps attach to individual machined aluminum mounting brackets (shown here).

Is Halon Illegal?
Halon is not a banned product, although some states are banning the sale of certain hand-held extinguishers for noncommercial use. Effective January 1, 1994, the production and importation of new halon was banned in the developed world by international agreement-the Montreal Accord. According to the EPA, halon releases that occur as a result of owner failure to maintain containing equipment to relevant industry standards are prohibited. However, this prohibition does not apply to emergency releases of halons for legitimate fire extinguishing, explosion inertion, or other emergency applications for which the systems or equipment were designed.

As you can imagine, the careful use and conservation of halon is important. According to conservative estimates, there is sufficient halon available to serve existing needs until the year 2040.

Halons are still the extinguishing agent of choice for contemporary motorsports applications. There are other compounds available, and yes, they'll work. Unfortunately, some just aren't as effective as halon. It all boils down to effectiveness versus weight versus cost. It's your choice.

In the end you can see that fire extinguisher systems are not as complex, heavy, or ugly as you might have first guessed. And they just might save you and your Corvette when you most need the help.

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