Is It Time to Change Our Training Yet? Part 1: Airbag Explosions
Lee Junkins, Midsouth Rescue Technologies
In June of 2005, I was the officer on the scene of a fully involved 2004 ford ranger pick-up, parked under a large tree. We put the fire out as normal, the men laid the hose down and removed their mask, I then assigned two other men to do mop up, there were no flames showing for at least five minutes. As the men opened the driver’s door, two explosions accrued and debris was thrown in all directions, narrowly missing the firefighters. Both the driver’s and passenger’s airbags had deployed in the mop up stage. In the investigation we found a 1 ½ x 3 inch piece of the nylon airbag, 47 feet behind the truck.
With this passenger’s airbag having a compressed gas inflator, I began to wonder if they would explode into shrapnel like the chemical inflators did. With the help of some friends at the bomb squad, we disassembled a few airbags and carried the inflators to the bomb range. We used traffic flares, (that you can hold in your hand), with remote strikers to heat the gas canisters. The large inflators exploded in an average of 20 seconds when exposed to the heat. We then tried the small inflators from, door and seat mounted, side impact airbags, these averaged 13 seconds.
My next concern was; how often can we expect a catastrophic explosion from one of these. We gathered many inflators, each identical, and exposed them to the same heat. The passenger’s airbag inflators were all 8" long and 2 ¼" in diameter, and contained 3000 psi of argon gas. When exposed to the heat of the flare, placed two inches from the middle of the canister, 92% of them released the gas like a normal deployment, 6% ruptured the side of the canister and 2% exploded into shrapnel. We then exposed twenty of the small inflators from side impact airbags, one exploded, two ruptured, and the remainder released the gas normally.
Of course this is not an accurate test, but it will make you think about: What would they do with the heat of a fully involved vehicle fire?
These canisters are felled with compressed argon gas. Argon will not burn or explode, but it has a very high rate of expansion when exposed to very little heat, causing the canister to rupture or bleve like an LPG gas bottle.