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With gas prices on the continual rise (estimated to be at $4 a gallon by summer), coupled with the amount of money invested by car manufacturers in the R&D of Hybrid and Alternative fuel vehicles, it is certain that these vehicles will start to become more mainstream in the near future.
The question now becomes - what is your department doing to address the issue? Do you have SOPs and training in place to educate your firefighters and provide a working knowledge of these vehicles? Are your personnel aware of the dangers they actually present and those they do not?
Let’s utilize this group to bring a better understanding of these vehicles to our fellow emergency responders and flush out any misunderstandings that exist. Please feel free to share any experiences you have had with hybrids and alternative fuel vehicles and what you learned from it. I will be posting information in the near future to assist responders in sorting through the information out there but in the meantime let’s start up a dialog about what everybody’s concerns are and address any questions that are floating around out there.
Jason-
Glad you started this discussion about this timely issue. The Seattle Fire Department has put together an outstanding power point about the hazards associated with CNG vehicles. They experienced an incendiary CNG vehicle fire that caused a cylinder to bleve. It is available through their web page.
Regarding hybrids, are you aware of any firefighter hazards associated with car fires in those vehicles?
Stay safe,
Doug
Thanks for joining in. I set this group up about a week and a half ago and haven't had a chance to run any updates as of yet. I am looking to get the word out about it so we can start up this healthy exchange of factual information rather than some of the stuff that is floating around out there now.
I do have a copy of that CNG presentation that someone recently forwarded but I haven't had the opportunity to review it in its entirety yet. I didn’t realize they had made it available on their website but I think I will add a link to this forum once I locate it.
As far as hybrid vehicle fires water is the most suitable agent for extinguishment. Although the application of water to a high voltage electrical system is counter intuitive to firefighting personnel, there is no risk of the electricity traveling up the water stream and causing the electrocution of firefighting personnel. Although still dangerous, DC (direct current), unlike AC (alternating current) power sources commonly found in buildings, does not seek a path to ground. Rather, DC electricity follows a path out from the battery, along the electrical circuit and back to the battery. As such, the electrical current will not travel up the hose stream as it possible with a high voltage AC power source. The danger of electrocution exists when firefighters accidentally place themselves into the electrical circuit by touching both the negative and positive side of the circuit simultaneously with either their body or equipment. The various safety systems on these vehicles, however, keeps the potential of this occurring to a minimum. Responders should consider that it may be difficult to identify the vehicle as a hybrid depending on the extent of the damage of the vehicle from the fire.
It is generally recommended that a standard offensive attack be conducted unless the NiMH battery pack is on fire. If this becomes the case, live fire testing has indicated that it is better to allow the battery to burn out rather than attempt to extinguish it. The reason for this is two-fold; first it is nearly impossible to get enough water directly on to batteries because they are encased in protective shell. The only real access for water to the battery pack is via the battery vent and many vent designs do not allow easy access for this. Secondly, if you allow the battery pack to burn out, concerns regarding the hazmat properties of the residual electrolyte will be negated. Additionally, if the electrolyte is no longer present, the battery will not be energized. Always make sure that the battery pack is cooled down enough to prevent re-ignition prior to releasing the vehicle. Thermal imaging cameras can be a valuable tool to determine if the battery pack is cooled down in vehicles where the battery pack can be accessed visually.
Attempts should be made to control runoff as the NiMH battery has cancer causing ingredients. If a defensive attack is warranted, pull back to safe distance and use a water stream to protect exposures and control the path of smoke. If the situation does not allow for a defensive attack, such as a vehicle in a garage, appropriate actions should be taken to protect the exposure.
High voltage components should never be overhauled as there is no guarantee that the system is de-energized. System safeties can be rendered inoperable by the effects of fire. Live fire testing has indicated that these components can remain live after a vehicle has been subjected to fire.
Hope this clears up any questions you had regarding hybrid cars fires.
if a hybrid is burning and exposures are a concern what about AFFF/ar foam??We are a small rural department and we carry a small amount of foam mostly for vehicle fires. should we reconsider the use of foam on hybrid? also with flex fuel vehicles becoming more prevalent, should we consider carrying more foam?
Good questions. When teaching I often get asked about the use of foam on a hybrid vehicle. The only reason I could see advocating the use of foam on this type of vehicle is if it were department policy to use it in the same situation with a standard vehicle.
Hybrids become more difficult to extinguish primarily when their battery pack becomes involved. Since many of the designs (battery placements) do not allow for hose stream to be applied to the exterior of the battery case, the fire will continue to burn inside due to lack of adequate cooling. In a situation where the battery case was accessible, continued application of water to the exterior of the battery case would eventually cool it down enough to prevent the unburned cells from reaching their ignition temperature.
Since foam is more of a smothering than a cooling agent, it wouldn’t be more effective than water in cooling the batteries, even if you were dealing with a model where you could reach the battery case with the foam stream. This is due to the fact that you would not be putting the foam directly on the substance that’s burning (battery cells) but using it to indirectly cool the cells.
In a situation involving exposures, I would advocate the use of an offensive attack to knock down the fire as quickly as possible. Once extinguishment has been achieved, if possible, remove the hybrid from the vicinity of the exposure and continue to monitor it to ensure that the battery pack is not burning. Also, consider requesting an additional company to provide supplemental water for the cooling process if you are unable to secure your own water supply.
The use of E85 in flex fuel vehicles does open up a new concern for firefighting personnel. The use of alcohol resistant foam is crucial to the operation due to the fact that since 85% of the mixture is alcohol and 15% is a hydrocarbon, it is going to act more like an alcohol. Since the typically available mixtures for AR-AFFF foam is 3%/6% or 1%/3% (hydrocarbon/alcohol) we will end up going through our foam supply much quicker if we have to run the mixture at the higher percentage.
For the amount of fuel most passenger vehicles carry, I would imagine that most departments that have foam would carry a sufficient amount of foam to handle a small spill. They would just need to make sure it was an alcohol resistant type. Larger spills such as those from a tanker would require a much greater supply and a network of mutual aid departments.
What I have instituted (with mixed results) is that we carry a small set of plastic wheel chocks on every fire company and ambulance. An an MVA before patient contact is established the front wheels are chocked. As soon as possible, preferable with the establshment of patient contact, the keys are removed from the ignitiona and at least 3 feet from the vehicle. Additionally, the parking brake is set. The goal is to prevent the car from moving if it starts up on its own. With such wide and varied versions of hybrids I am trying to take a generic approach. I tried positioning the wheel chocks in a location that would prompt thier use but it has been marginal with compliance.
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