Side Airbag Tank Explosion Complicates Extrication of Victim

In October 2006, a two-vehicle accident occurred in northern New Jersey in which there was frontal off-set damage and a driver was medically entrapped. The vehicle involved was a 2006 Volvo S80 sedan (photo 1). The vehicle was stabilized; the rescue team action plan was to remove the roof to facilitate the driver’s disentanglement. The glass was managed, and the tool operator proceeded to cut the passenger side C post. As the tool operator cut the roof post, the hybrid gas generator (inflator) cylinder for the passenger side curtain supplemental restraint system (SRS) was inadvertently squeezed between the power hydraulic cutter blades. As the inflator was compressed, the approximately 6,000 psi of nitrogen gas it contained was also compressed, eventually causing the cylinder wall to fail, resulting in a loud detonation that sent debris around the incident scene (photos 2, 3).


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Photos courtesy of author.

 


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Although this occurrence did not further injure the victim or seriously injure the tool operator, it effectively halted the extrication. As a result, the roof removal evolution was abandoned. Instead, rescuers improvised a roof flap by severing both vehicle A posts, hyperextending the roof upward, and removing a door to disentangle the victim. Although no one was injured in this incident, the disentanglement was delayed as personnel reassessed the situation and came up with another plan of action to displace enough material to remove the victim. So let’s look at these devices again.

SIDE CURTAIN SRS

These safety systems can be found in any type of vehicle today, including fire apparatus and large trucks. This SRS usually deploys downward from the roof edge and fills in the space from A post to the last roof post in the vehicle (photo 4). However, depending on the vehicle, this curtain may be in two sections because of the vehicle’s length and may even deploy upward from the top of the door in retractable roof convertibles. Designed to protect the occupant’s head and upper body in a crash, this curtain also provides a barrier to keep the occupants inside the vehicle in a rollover. Although equipped with electronic sensors, these devices deploy using stored energy. The gas to inflate the bag is stored for deployment inside the cylinder (photo 5), unlike frontal SRS, in which two chemicals combine to produce the gas to inflate the bag. This stored energy to inflate the bag takes the form of high-pressure inert gas stored in a pressure vessel or pyrotechnics. Just like side impact SRSs systems, these devices can be affected by outside forces such as back surge, short circuiting, impact, and pressure.


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Also like side-impact SRS devices, side curtain SRS devices are located in the vehicle passenger compartment where we work regardless of which tool evolution we perform (e.g., roof, door, or dash displacement). The cylinder that inflates the side curtain air bag may be found within the A or C vehicle posts or even along the inside edge of the vehicle’s roof. Also remember that in vehicles with large side areas, rescuers may find two inflation devices or one large cylinder (photos 6, 7). On arrival, many times we may find these bags still fully or partly inflated because of their role of being a barrier during a rollover.


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OPERATIONS

Let’s review the best practices for dealing with these devices on-scene. First, we must manage the hazards we found on-scene and then ensure that we shut down the vehicle’s power. This shutdown process begins with turning the vehicle off and placing the key in our apparatus. Remember, an increasing number of vehicles today can have proximity ignition, thus having no metal key.

Then we need to try to find the 12-volt battery and disconnect the positive and negative battery cables. After securing the vehicle’s power, we should stabilize the vehicle to ensure a minimum of unwanted movement.

If we observe that a side curtain bag has deployed, we know that the gas in the cylinder on that side of the vehicle has been expended. Also, in the deployment process, the interior trim on that side of the vehicle from which the bag deployed will be displaced, making it easier to find the gas cylinder. So far, the cylinder locations are mirrored, so if we find it on one side, it will be in the same location on the other side. We need to find that cylinder so we can avoid cutting it.

What if we do not have a side curtain deployment as in our incident above? We need to displace interior trim (both roof post and roof edge) to locate the inflation cylinder (photo 8). But with what tool? The best tool for this application is a small prying tool-a cat’s paw tool, an officer tool, or even a trim puller (photo 9). We need only to displace, not remove, trim, since the cylinder is fairly large and will be readily seen.


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Once we do identify such a cylinder, next we need to evaluate where the roof post cut will go (photo 10). The preferred methodology is to cut below the cylinder and leave it attached to the roof. Sometimes, however, this will not be possible or practical, and we will be forced to cut above it. If so, we will need to feel the end of the bag if it covers the cylinder and find where the cylinder ends and then cut above that. Some bags have an inflation tube from the cylinder to the bag; it is okay to cut through.


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We need to be cautious of wiring running to the device as well. Cut this with a hand tool, such as cable cutters, medic shears, or even a knife-not with a power hydraulic cutter because of static charge concerns, especially if the battery has not been disconnected.

Once the roof has been removed, be careful of how you place it on the ground because live devices are still in the roof. The best practice would be to place the roof with the exterior down and make all personnel aware of the debris containing live or “loaded” devices.

Finally, as with any tool evolution, make sure you protect the patient and interior rescuer with hard protection and cover up sharp edges after the roof is displaced (photo 11).


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Although this incident could have had worse outcomes, it is a good lesson for us all. It is an obvious reminder that we need to displace roof trim on all roof evolutions today. Today’s vehicles are quite different from those of 10 or even five years ago. Although today’s technology issues can be bewildering at times, more often than not, they can be managed by applying a little knowledge and some common sense and basic skills.

DAVE DALRYMPLE is a career EMS provider for Robert Wood Johnson University Hospital/St. Peter’s University Hospital Emergency Services in New Brunswick, New Jersey. He is also a firefighter/EMT/rescue technician and former rescue services captain of the Clinton (NJ) Rescue Squad. Dalrymple is the education chair of the Transportation Emergency Rescue Committee-US and serves on the Expert Technical Advisory Board of the International Emergency Technical Rescue Institute as the road traffic accident advisor.

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