03-24-2001, 09:06 PM #1rmooreFirehouse.com Guest
Answer to What's a Typical "Drain Time"
Received this question from a fire department in the Pittsburgh PA area-
What would you consider adequate time to drain any airbag equipped vehicle once the battery has been disconnected? I realize most, if not all, makes and even models are probably different, but we are looking for an upper end so we know what our limits will be.
My reply follows. Anyone else have some suggestions?
A couple of ideas regarding the capacitor drain time. You can reference NHTSA's website to read over their list of posted drain times. Or you can buy the Holmatro airbag book and read up on each individual vehicle's airbag "drain time". You can even purchase Sally Straight's new book on airbags to check this out for yourself.
What it all boils down to is this. There are old airbag-equipped vehicles on the road today with drain times reported at 10 minutes, some 20 minutes or even longer. These are not the most common vehicles you'll run into today. A vehicle built within the last few years may have a drain time ranging from 2 minutes to only one second. Some 1999, '00, and '01 vehicles have a drain time of '0' seconds. (I don't know why they even have a capacitor if the drain time is zero!)
Basically, the newer the vehicle, chances are the shorter the drain time. I train our Plano firefighters that the typical late model vehicle drains in 2 minutes or less. Problem is, this really doesn't mean much anymore. Any undeployed airbag is to be considered 'loaded' regardless of elapsed time since the electrical system was shut down.
If you research NHTSA's section on recalls and search for airbag recalls, you'll see hundreds of thousands of airbags being recalled because they are sensitive to static electricity, shock sensitive, moisture sensitive, and more.
We cannot make a loaded airbag 100% safe at a crash scene. Taking away the power is the best first step. But this step must be followed up with airbag scanning, respecting the 10"-18" and 5" inflation zones, and always being aware of the potential that a loaded airbag presents.
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