1. #1
    Firehouse.com Guest

    Default Airbag Self-Deployment

    A Posting From Ron Moore, Forum Moderator

    On Wednesday, 3-10, I burned a 1995 Honda for another of my 'field tests'. That sedan had undeployed dual front airbags.

    I planned on verifying what the automakers call the 'auto-ignition' feature of sodium azide.

    I was told buy automaker engineers that when this inflation chemical reaches 280 degrees F, the sodium azide reacts spontaneously. The front airbags are supposed to deploy just as if the car were involved in a front collision. I hoped to see the nylon bags deploy and instantly melt.

    With video cameras rolling, I lit the newspaper that I had stuffed up under the dash. About four sheets of paper ignited with a match. No accelerants.

    At 40 seconds into the fire, flashover occurred. Remember now, I had already removed both front doors of this 4-door so the cameras could get a good view.

    Flames were now peaking over 8 feet high coming out the back window. Suddenly a giant pop and a long extended hissing sound for about 12 seconds. It was like a tire that just ran over a nail and was leaking air.

    At the instant the pop occurred, a huge blast of smoke in a very narrow jet-like shape shot straight out the driver's side a distance of 15 feet. We got this on video. I came almost right towards the camera.

    A pure white fireball can then be seen moving through the car and blasting out the rear. The temperature of this fireball was so hot, it registers pure white on the video.

    Honda engineers will be shown this clip on Monday, 3-22. They feel the pop, blast of smoke and hissing sound was the driver's airbag module auto-igniting out the back side of the inflator module.

    What was peculiar was that we let the fire burn for only 3:10 minutes and then knocked it down. In that short period of time, total burnout! Nothing combustible left in the car to burn.

    The airbag covers melted away and the still undeployed dual front airbags had begun to melt from the radiant heat. But they were still completely folded just like the day they were put into the car. I got good still pix of the aftermath.

    I'll let you know what the Honda people say when I meet with them Monday. Stay tuned!


  2. #2
    Firehouse.com Guest


    I may be jumping the gun here, but since the bags did not deploy, are we to assume (yes I know) that this is how all bags will react, the inflator will vent but the bags will remain folded?

    Also, can anyone provide some specifics on how Ford's deployable trim works? Is it a pyrotechnic device, mechanical...?

  3. #3
    Firehouse.com Guest


    Kpywell asked about the airbag fire test I did on the Honda. I have seen actual fires where after knockdown, both airbags were detached from their original locations and had melted into the carpet on the floorboards. This being the case, these bags must have deployed as they would have in a crash, then instantly melted away and dropped to the floor. My Honda test video is still being evaluated by Honda engineers in California( as of this date, 3-30-99, no word back from them). I think the inflator modules vented out the side or the back end and the bags were starting to melt in their stowed and folded condition.

    The other thing you asked about is the Ford Deployable Trim. This is just an inactive combination of plastic and padded trim on the side and the door. In a side impact, the panels and trim react in a pre-determined way to cushion up against the occupant. There is no real deployment like an airbag. It's all design and trim material placement.

    Ron Moore

  4. #4
    Firehouse.com Guest


    Read BURNSEMS post on the Firefighters Forum page under "Air bags in car fires", ignited by EML89. Another air bag went pop in a car fire.

  5. #5
    Firehouse.com Guest


    Any news yet from the engineers? So much for my departments' "agressive attack"- advancing the hose stream right up to the burning car and sticking the nozzle into the window. I always like to knock down the fire from as far away as I can, then advance. The fire seems to go out just as fast as "the agressive attack" but for some reason, I feel safer doing it from a distance. Thanks, Ron for making my point!

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