How many times have you been told there are electrical storage capacitors that can fire air bags upwards to 15-30 minutes post battery disconnect? I would bet many have heard the same. Well here is one for you from 2009 during a training evolution that fortunately no one was injured. This Volvo had NO BATTERY in the vehicle for well over a year.
Here is the firefighter safety alert I created for our FB Training Page because many are mis-informed about de-energizing the vehicle's electrical system is the safest method prior to first responder extrication operations.
The Volvo Car Manufacturer in the early 1990's designed their side impact air bag system to be armed and ready to activate without ANY power source. This SIPS system is not even shown on the electrical schematics for the cars wiring system. Recent training by a local department had an example of having a car without any battery in it, still remain with ACTIVE airbags.
After following up with a Volvo Master Service Technician at the dealership, he stated that PRE-1998 Volvo's equipped with SIPS - Side Impact Protection Systems do indeed have a firefighter or service technician hazard even if the battery was disconnected. The SIPS is designed separate from the SRS system that fire the steering and dashboard airbags. POST 1998 Volvo’s were re-designed with a new system that works similar to the energized SRS.
SIPS does NOT require energy to fire the air bags located in the seats. It has its own battery power supply similar to a watch battery built right into the system. Therefore, the SIPS system is ALWAYS waiting for an impact. An impact sensor located below the plastic trim molding just inside the rocker panel to be impacted. The dash and B-post have warning decals identifying the hazard. The plastic molding has SIPS labeling as well. These warning decals identify: DO NOT USE EXCESSIVE FORCE IN THE AREA OF THE SIDE SEAT.
To disarm the SIPS sensor, there are two wires coming from the impact sensor and running underneath the
seat to the torso airbag. On our training Volvo, the wire was noticeable from the open door where the bottom
seat cushion meets the upper back seat at the hinges (see photo below) There appears to be enough room to cut this wire with a pair of trauma sheers or a knife without intruding on the patient's buttocks.
Reminder that the de-energizing the 12V battery in the engine compartment, will disarm the SRS system
but if the vehicle is equipped with SIPS, the side impact sensors will need specific attention by first responders.
The safest method for first responders is to be educated. During our extrication training drills we enforce that firefighters and rescuers MUST respect the air bag impact zone. If we do not, then we are putting ourselves, our men and women at risk should the system fail, or the vehicle have a unique power supply system. Stay safe my brothers.
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