BY DAVID DALRYMPLE
Although most incidents requiring management of a motor vehicle involve an accident or a medical emergency, a vehicle fire today is another story. In all vehicles today, whether conventionally or alternatively fueled/powered, the drivetrain carries a significant fire load. Although plastics, combustible alloys, and components such as gas struts are present in every vehicle, hybrids and all-electric vehicles carry even more combustible alloys; composites; and a very large high-voltage battery pack, featuring nickel metal hydride, nickel cadmium or nicad, or lithium ion battery cells. The combination of all these components creates a difficult problem for the firefighter (photo 1). These changes involve not only tactical considerations on scene but even the choice of suppression agents to effectively mitigate such an incident. As vehicle technology continues to evolve, emergency responders need to keep pace with it and update their tactics as needed.
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| 1 Photos courtesy of author. |
EXTINGUISHING AGENTS
Vehicle technology has changed greatly, particularly motive power, especially over the past decade. Although simply applying water is acceptable, because of the components involved, hybrid and electric vehicle fires require copious amounts of water to fully extinguish (photo 2). Many times, the water needed will exceed what is carried on the apparatus, especially if the fire is not out in the open but is in an enclosed area (e.g., a garage, a parking deck, or even a parking lot). The rapid fire expansion and high heat will quickly involve the vehicles around the involved vehicle.
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One area we truly need to revisit is the use of foam and wetting agents (especially the newer ones) that enhance the water’s suppression properties. Even with these agents, we need to explore some of the new technology. Class A and B foam aren’t always the best solutions. Some newer gel and foam wetting agents actually work better on Class B and D fires, including fires in which the vehicle’s structural components are burning. These agents are biodegradable, leave no residue on the road surface, and work well in pressurized water extinguishers and apparatus tanks.
ENGINE ACCESS REVISITED
In addition to suppression, crews need to gain access to allow a nozzle into the engine compartment to mitigate a fire (photo 3). Since most vehicle fires begin in the engine compartment, crews will need to make access through the vehicle’s hood. But the conventional tactics to force hoods may put crews at risk with hybrids and electric vehicles (photo 4). One traditional tactic to obtain some access is to drive the spike of a halligan tool into the corner of the hood, twisting the tool around and folding back the hood toward the rear (photo 5). This presents a problem since the vehicle’s high-voltage drivetrain components may be in or near those corners. Although by the time the crew arrives the high-voltage power should be drained down, driving a spike into such a high-voltage component might present a shock hazard.
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Another popular tactic is using a rotary or reciprocating saw to make a plunge cut in the hood to create an “X” or some sort of space to obtain engine compartment access for the nozzle. This tactic presents an even greater risk of cutting into high-voltage components or even the electric drivetrain itself (photo 6). One viable option is the use of a combination tool to “tent” the hood on each side, basically in line with the vehicle’s front suspension (photo 7). This method allows the crews to see under the hood, possibly offering access to cut the hinges or sever the hood’s front latching mechanism.
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Combustible metals may be found in all vehicles today, although there are larger amounts in hybrid and electric ones. In the past, a Class D extinguisher or a large amount of water would be used; sometimes these tactics are not practical (photo 8). Also, many times we will find these combustible materials while our offensive attack is in progress, which presents additional hazards to our crews and possibly requires bringing additional resources to mitigate the fire.
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In all vehicles, a common location for this material is the crash box in the vehicle’s steering column. But this material is also used for structural pieces and various vehicle components and the like. It’s not easily identifiable through casual observation in a nonemergency situation, let alone when the vehicle is fully engulfed in fire (photo 9).
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GAS STRUTS
Another concern is gas struts, which now support most hoods. Since it is a pressure vessel, when heat is applied, the gas inside the cylinder expands to the point where the strut cylinder fails, thus releasing the hardened steel rod. This rod can easily punch through the vehicle bodywork and travel quite a distance, more than 80 feet. This puts responders in harm’s way when they approach the front or rear arc of the vehicle. Although many times these devices will explode without causing harm, blunt force trauma strikes and even impalements from the strut rod itself have occurred. Even struts from the rear of the vehicle are dangerous.
Remember that people carriers (minivans) and SUVs may have more than four struts in the rear hatch area (photos 10, 11). Also, in upper-end vehicles today, a small gas strut has replaced the strap that holds the door partway open and prevents overextension. The strut points outward from the vehicle. It’s something new to consider (photo 12).
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POWER ISOLATION
An emergency responder’s best defense today, after good up-to-date vehicle information, is power isolation. This is a two-step process. First, shut the vehicle off and secure the ignition key away from the vehicle, placing it in the apparatus. Second, locate the primary 12-volt battery and disconnect the positive and negative cables. Although power isolation may be difficult, if not downright impossible or impractical at a fully involved vehicle fire, attempt it whenever possible. Vehicle power is not a responder’s friend, and power isolation is important for any vehicle emergency, whether it’s a crash, a fire, or even a medical emergency involving an occupant.
Think about this: Hybrids and electrical vehicles can and will be “silent” although still operating when the vehicle is stopped, and even some “conventional” drivetrain vehicles now shut down when stopped (photo 13). In the past, we used our ears and eyes to determine if the vehicle was shut off. Now, a critical component of our size-up is to ensure the vehicle is indeed shut down by at least turning the vehicle off and moving the key to our apparatus because of the ever-increasing use of proximity (wireless) ignition keys. If there is a family in the vehicle, there may be more than one key within the vehicle’s range. A short time ago, we would never have had to think about this.
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Then, find the primary 12-volt battery and disconnect the positive and the negative cables. In more than 40 percent of vehicles today, the battery is outside of the engine compartment; sometimes vehicle damage may prevent us from even accessing the battery. Moreover, some vehicles have more than one battery.
All these factors increase the risk to responders. Although vehicle fires are a common, everyday emergency, we now need to act with greater caution and truly “think and work smart.” Complacency can injure your crew. Although extrication concerns of today’s vehicles are much discussed, we also need to focus on firematic issues, especially those concerning hybrids and electric vehicles.
Today’s vehicles carry a much greater fire load than in the past. This will only increase and make our firefighting efforts more difficult, requiring us to adapt methodology and tactics accordingly.
DAVID DALRYMPLE is a career EMS provider for the RWJUH Emergency Medical Services in New Brunswick, New Jersey, and a volunteer firefighter/EMT/rescue technician for Clinton (NJ) EMS/Rescue. He has been actively involved with emergency services for 27 years. He is the education chair of the Transportation Emergency Rescue Committee-US (TERC), is a certified international level extrication assessor, and serves on the Expert Technical Advisory Board of the IETRI as the road traffic accident advisor. Certified as a NJ fire service instructor, he has been teaching transportation rescue topics for more than 16 years. He is the executive educator for Roadway Rescue LLC, an educational team for transportation rescue training. He is an ICET (Netherlands) certified registered International SAVER instructor. He writes on extrication tactics for Fire Engineering and contributed to Fire Engineering’s Handbook for Firefighter I and II (2009). He received the 2007 Harvey Grant award for excellence in rescue education. He is featured in Training Minutes on vehicle extrication on fireengineering.com.
