Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Air bag concerns.  (Read 950 times)
G7HEU
Member

Posts: 261


WWW

Ignore
« on: April 23, 2004, 07:19:35 PM »

Did I read somewhere about a vehicle mounted transceiver causing an air bag to deploy? Did I dream it? Perhaps it's just another urban legend?

I've just installed a 100W HF radio in my car and nothing has gone bang yet but I confess to being slightly concerned.

Should I worry?

Thanks

Steve
M0HEU / G7HEU.
Logged
OBSERVER11
Member

Posts: 657




Ignore
« Reply #1 on: April 23, 2004, 08:31:49 PM »

a transmitter did not cause the airbag to deploy, but the concern about transceivers and air bags is the placement of the transceiver. Air bags EXPLODE when deployed, you do not want a radio shot at you if the air bag were to fire.
Logged
K0BG
Member

Posts: 9879


WWW

Ignore
« Reply #2 on: April 24, 2004, 09:22:39 AM »

Actually Steve, that may have come from me.

Using the vehicle's factory wiring to power an amateur transceiver is not a good idea. Nowadays, the wire gage (yes, that's the way they spell it) in cars is barely large enough to handle the load imposed upon it. It's a weight-saving thing.

If you hook into the wrong circuit, or induce enough RF into the circuit, there is a remote chance the airbag (they're not airbags obviously) could fire. About 8 years ago, Ford Motor Company issued a warning to dealers about wiring police radios in Ford cars. Apparently, there were several reported cases of airbag deployment caused by RFI.

If you look over the NHTSA's accident reporting site, and do a search, you'll find several instances where airbag deployment happened while in motion without actually hitting any thing. Whether or not these cases were caused by RFI would be conjecture. So, my simple question is, why take a chance. Wire your rig directly to the battery!

Alan, KØBG
Logged

KD5JFT
Member

Posts: 82




Ignore
« Reply #3 on: April 25, 2004, 12:12:27 AM »

I must second the note about mounting radios (or anything else) in the airbag deployment zone.  I have worked several accidents where serious injuries were sustained from items impacted by the airbag and propelled at GREAT FORCE into vehicle occupants.  I have a set of pictures I took of one accident where the passenger side airbag took out a rear facing child restraint seat (no occupant; thank God) and then bounced off the seat and shattered the front windsheild.  There was minimal damage to both vehicles except for that caused by the airbag.  The child restraint seat was shattered.  I use these pics in presentations on the importance of properly installing child restraint seats.  I have seen advisories on installing various electrical equipment into vehicles, but most dealt with possible shorts or surges setting off airbags.  I am not an expert on this though.  
I always use direct connect to the battery.  The place that installs our lights, sirens, and radios sucks!! I have had three cars catch on fire due to faulty installations, once while on a traffic stop.  The violator said he smelled smoke and looked back and my light bar was on fire.  I called the fire department and continued to write the ticket.  I figured if I was going to get into trouble for burning up another car, I might as well get a ticket out of it.  We used to get blamed for anything that went wrong whether we had anything to do with it or not.  I no longer trust anyone but myself to install any equipment.  I can't change anything with my work vehicles, but my personal vehicles will never have that problem.

KD5JFT
Logged
K0BG
Member

Posts: 9879


WWW

Ignore
« Reply #4 on: April 25, 2004, 03:13:15 PM »

KD5JFT, would you be so kind and e-mail me the picture you spoke about? Or e-mail me and I'll tell you why I want it.

Alan, KØBG
k0bg@aol.com
http://www.k0bg.com
Logged

G7HEU
Member

Posts: 261


WWW

Ignore
« Reply #5 on: April 25, 2004, 06:24:37 PM »

Thanks for the replies all. Just got back from a 300 mile round trip with no RF induced problems.

I use a seperate battery for the radio so it looks like I can stop worrying. I was already well aware of the dangers of putting things in front of air bags.

My best contact was on 20Mtrs to a special event station in Italy. He was operating from what used to be Marconis' house - I think I'm going to enjoy H.F. mobile!

Steve
M0HEU / G7HEU.

p.s. A friend of mine rolled his Alfa Romeo and none of the air bags deployed.
Logged
WB2WIK
Member

Posts: 20611




Ignore
« Reply #6 on: April 26, 2004, 06:15:06 PM »

It would be possible to "roll" a car without the air bags deploying, since the activation mechanism senses very fast deceleration, as happens when you hit something.  If you go into a roll without any serious deceleration, I can see how the mechanism wouldn't fire.  Of course, the mechanisms probably vary nowadays -- I'm recalling the way the original sensors worked, which was a kind of pendulum device similar to what keeps seat belts/shoulder harnesses snug in a collision, but then lets you pull them away if parked.

Then, maybe they are supposed to deploy, but didn't because the Alfa was built during the afternoon Vino break...

The advice about keeping objects out of the path of explosion in the event of an air bag activation is good.  I cringe when I see people using Velcro and stuff to hold their remote front panels for rigs, sometimes directly in the path of the potential bag explosion.  It must hurt a lot to be hit in the mouth with a front panel at hundreds of feet per second.

WB2WIK/6


Logged
AD0AC
Member

Posts: 36


WWW

Ignore
« Reply #7 on: April 28, 2004, 04:56:16 PM »

SRS systems aren't going to be deployed by any kind of RF. The systems are set to respond to various sequentially-triggered sensors, all of which must agree in order to trigger the final switch, usually a powder-driven pyrotechnic switch, which then sends the signal to the SRS module to fire and deploy the restraint. It's all a combination of deceleration and force that the computers use to determine whether or not to deploy the restraint. "Airbags" do not explode, they deploy and the "bag" immediately deflates to aid egress from the vehicle. It is not uncommon for people to sustain superficial light burns from the hot gas exiting the bag via large vents.

Automakers have recalled vehicles in the past because of defects in the restraint module that cause a deployment or fire, but no amateur RF transmitter is going deploy the restraint. You would have to be operating on the same frequency as the digital electronics at high power to even come close to triggering one of the sensors. If the restraint deploys while you are driving, chances are you'd be able to stay in control of the car long enough to stop safely.

If, for some reason, hell freezes over and your radio trips a sensor out of sequence, the computer would automatically shut down the entire SRS system and a warning light would come on the dashboard somewhere. This light means that the system is fully "safed" and the restraints cannot deploy. It also means that the system requires service, which may be expensive if you're out of warranty.

Relax, your radio isn't going to set off the airbag...
Logged
G7HEU
Member

Posts: 261


WWW

Ignore
« Reply #8 on: May 01, 2004, 03:51:47 AM »

Keyed the mic on 20Mtrs this morning and all four air bags went off. It's made a heck of a mess.


Not really! Thanks again for all the replies.

Steve.

Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!