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  1. #1
    **THIS SPACE FOR RENT** Doo600's Avatar
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    Default Could you clear up a few things for me

    When doing a roof removal of a vehicle equipped with a side curtain airbag it is necessary to somehow disconnect that system from the roof in order to remove it. How should it be done. I have been told to pry off the canister but that seems crazy to me. Obviously I'm not cutting the wires and cutting the bag seems as if I could have a huge issue if the charge activates. What's the recommended practice?

    Dual stage inflators operate due to severity of the impact and not patient weight. Right?

    Thanks all


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    My understanding of how to deal with these airbags is to disconnect the battery and pull away the trim to check for inflators. Just don't cut the inflators and you should be OK. Any wiring in the A, B, or C posts will be cut when you cut the post. I have not heard of any reason to mess with the airbag system itself and think that it's better to leave it alone.

    I don't know much about the dual stage airbags, but my understanding is the same as yours, that they are activated by the acceleration, not the weight of the passenger.
    Last edited by Eng34FF; 05-09-2007 at 01:32 PM.

  3. #3
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    I have been taught that if you can get at the actual bag itself cut it away from the inflator or from the tube that is between the bag and the inflator. that way if the inflator canister fires it will just be a big poof of air.

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    When doing a roof removal of a vehicle equipped with a side curtain airbag it is necessary to somehow disconnect that system from the roof in order to remove it. How should it be done. I have been told to pry off the canister but that seems crazy to me. Obviously I'm not cutting the wires and cutting the bag seems as if I could have a huge issue if the charge activates. What's the recommended practice?

    Most important thing before any other operations, is disconnect or double cut the battery cables, (neg. first), this in turn starts the drain time for the capacitors; (Average Drain time is 5 min.)

    Second most important thing always peal the trim and look before you cut anything, some vehicles have more than one curtain per side and each will have itís own canister. They can be located in the A post, C or D post, or anywhere along the roof rail and some even over the rear glass.
    (Stay out of the deployment zones while doing this)

    There is no reason to remove the curtain airbag from the roof, leave it intact and do not try to pry on the canister you could rupture it.
    Once you can see what is there, it is safe to cut anything around the canister, just do not cut the canister itís self.
    By the time you get to this point the drain time will be over, and it should be safe to cut the wires along with the post,(If for some reason you are scared to cut the wires, use a set of side cutters and cut them one at a time, (no chance of shorting).
    Now remove the roof and airbags, it is a good idea to set the roof in a separate place from the rest of the debris pile so that scrap metal is not thrown on top of the airbag should it accidentally deploy. (Always lay roofs and doors in the debris pile with the bag side up.)

    As for cutting the bag: it is a bad habit to get into, however it is not going to hurt you, until the bladder inside the canister opens, the bag itís self is just a folded piece of nylon, yes if the canister was to deploy you would get a sudden blast of hot nitrogen or argon possibly injuring or at least scaring your patient. (Bad idea)
    Keep in mind that no curtain or side impact airbag is dual stage, if the bag is already deployed you do not have to worry about it. But if one side is deployed the other side normally will not be.

    Dual stage inflators operate due to severity of the impact and not patient weight. Right?

    I don't know much about the dual stage airbags, but my understanding is the same as yours, that they are activated by the acceleration, not the weight of the passenger.

    You are both almost right:
    They are deployed according to the Deceleration and Severity of the crash. The weight sensors and many others sensor help the control module to determine how to deploy the airbags. (Low side, high side, or not at all, Etc.)
    Last edited by LeeJunkins; 05-09-2007 at 01:57 PM.
    http://www.midsouthrescue.org
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  5. #5
    **THIS SPACE FOR RENT** Doo600's Avatar
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    Default

    Thanks for the replies. I thought cutting the side curtain would be necessary because it attaches to the post and then wiring goes down inside the car. No way that roof would come off when it's all still attached.

    Cutting the bag scared me becasue of the gases and if you leave a section of bag intact and it fires that sucker could whip someone pretty hard. I think our S.O.P. will be if necessary to expose the wiring for the unit and cut it one wire at a time just prior to roof removal.

    So the dual stage acts from both weight and deceleration. Interesting.

    Thanks Lee!

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    Quote Originally Posted by Doo600 View Post
    Thanks for the replies. I thought cutting the side curtain would be necessary because it attaches to the post and then wiring goes down inside the car. No way that roof would come off when it's all still attached.

    Cutting the bag scared me becasue of the gases and if you leave a section of bag intact and it fires that sucker could whip someone pretty hard. I think our S.O.P. will be if necessary to expose the wiring for the unit and cut it one wire at a time just prior to roof removal.

    So the dual stage acts from both weight and deceleration. Interesting.

    Thanks Lee!
    Doo600í
    If you are writing SOPs on this you might want to take a look at some of these, it will help you understand a lot more about it

    http://www.sceneoftheaccident.org

    www.midsouthrescue.org

    http://www.moditech.com
    Last edited by LeeJunkins; 05-09-2007 at 04:27 PM.
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    They are deployed according to the Deceleration and Severity of the crash. The weight sensors and many others sensor help the control module to determine how to deploy the airbags. (Low side, high side, or not at all, Etc.)
    Lee

    Thanks for the correction. It's the engineer in me coming out. I'm used to only talking about acceleration with deceleration being just a negative acceleration.

    Great info about the side curtain bags.

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    This discussion kind of leads into some fuzzy areas I've had. Maybe some of you could help clear them up.

    1. We routinely tell our people that they must stay out of any airbag deployment zones, while working an extrication.
    2. We generally warn vehicle owner/operators that once a vehicle has been in an accident we cannot be certain that the airbag deployment system hasn't been compromised which may pose a risk to unexpected deployment if the car is driven after a minor damage MVA. This is mostly due to our not being fully trained on the mechanisms that actually deploy the bags. It is made perfectly clear that we do not tell people what is driveable and what is not, that's left to LE.

    The question or issue that comes from this and reading some of the responses from many of those more in tune with this stuff than me.

    If I now understand correctly, the airbag deployment systems are at least a two step system requiring both inertia (deceleration?) and impact to trigger the bag(s). If this is the case, then it should be fairly safe to drive a vehicle that has been in an MVA but didn't deploy any or all of the airbags. Or at least safe from unexpected deployment as one might argue the car is less safe if the bag has deployed. This also ties in with the two stage bags where only one has triggered.

    If I am correct to this point, then can we safely assume that any operations in a vehicle with undeployed bags are safe as long as no cutting or similar operations are happening. IE: standard board and collar/KED situation? I would still like to see the power cut, but this should be a moot point?

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    This discussion kind of leads into some fuzzy areas I've had. Maybe some of you could help clear them up.

    1. We routinely tell our people that they must stay out of any airbag deployment zones, while working an extrication.


    Extremely important on every MVA, major or minor.

    2. We generally warn vehicle owner/operators that once a vehicle has been in an accident we cannot be certain that the airbag deployment system hasn't been compromised which may pose a risk to unexpected deployment if the car is driven after a minor damage MVA. This is mostly due to our not being fully trained on the mechanisms that actually deploy the bags. It is made perfectly clear that we do not tell people what is driveable and what is not, that's left to LE.

    There is a full thread on this here on the forum, after all the discussion I believe most everyone agreed that no matter how much you do or do not know about the systems it is a good policy to stay away from telling the owner whether to drive the car or not, for our own liabilities sack.

    The question or issue that comes from this and reading some of the responses from many of those more in tune with this stuff than me.

    If I now understand correctly, the airbag deployment systems are at least a two step system requiring both inertia (deceleration?) and impact to trigger the bag(s). If this is the case, then it should be fairly safe to drive a vehicle that has been in an MVA but didn't deploy any or all of the airbags. Or at least safe from unexpected deployment as one might argue the car is less safe if the bag has deployed. This also ties in with the two stage bags where only one has triggered.

    This is probably the hardest part to explain about the systems, because there are so many different factors involved in the deployment of todayís systems.
    The simplest way I know is to look at the first system we had, the early single stage driverís frontal airbag. A crash sensor was mounted at the front of the car, inside the sensor was a ball attached to a magnet, the sudden stop of the car caused the ball to break loose and it rolled down the tube and made contact with two points completing an electrical circuit, this sent a signal to the control module that we have a crash. This is were people get confused as to whether it is Deceleration or Impact. Most of todayís systems uses a computer chip called an accelerometer that actually measures the sudden Deceleration of the vehicle and sends a signal that we have a crash.
    The actual two steps you are talking about is that neither of these will deploy the airbag, the control module must receive a second signal from the safeing sensor, this is a sensor that must also sense the crash to confirm that it is a true crash, on the earlier cars it was mounted inside the car and the crash had to be hard enough for it to feel the impact, then it sent a second signal to the control module and it would deploy the bag. This stopped the bag from deploying in a fender bender. Today most all of this is built into the control module itself much like a computer.
    In direct answer to your question this is what makes it UNLIKELY to deploy after the crash, But on todayís systems there are so many other factors involved that we can not say for sure that it will not deploy.

    If I am correct to this point, then can we safely assume that any operations in a vehicle with undeployed bags are safe as long as no cutting or similar operations are happening. IE: standard board and collar/KED situation? I would still like to see the power cut, but this should be a moot point?

    Do not take that chance!
    Todayís vehicles have weight sensors, occupant position sensors, seat position sensor, and on and on.
    Example: Say the weight sensor told the control module that there was less than 45 lbs or a baby in the passengerís seat at the time of the crash, it would not have deployed that airbag, but now your rescuer opens the door and gets in to help the driver, with the electrical system still in tact the control module now says there is a full size person in the seat and opens the path to the high side, if for some reason there is a short in the wiring say from a damaged wire under the hood and a charge ran back through the system, your rescuer could be in great danger.
    Remember as long as there is power the control module well continue to evaluate any change in positions and make adjustment to deploy the airbags accordingly. All we need is a feed back and we are in trouble.
    http://www.midsouthrescue.org
    Is it time to change our training yet ?

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    Lee, thanks for the prompt response. You have pretty much summed up what I've read here and on a few of the sites I've used to follow up. We are finding it difficult to remain as up to date with extrication training in today's environment. More and more mandated training in all realms especially those that have a very low impact on the functional emergency part of the job. Couple this with many dept's getting new sets of rescue tools, we just don't do nearly as much rescue/extrication as we used to. I'm afraid that realistically the new care technology is outgrowing our training so rapidly that rescuer safety is suffering. It doesn't seem far off that staying out of the deployment areas will be next to impossible to do. Sadly it's going to take a tragedy to get balance between operator/occupant safety and post crash safety.

  11. #11
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    Quote Originally Posted by LeeJunkins;808385
    [COLOR="Red"
    If I am correct to this point, then can we safely assume that any operations in a vehicle with undeployed bags are safe as long as no cutting or similar operations are happening. IE: standard board and collar/KED situation? I would still like to see the power cut, but this should be a moot point?[/COLOR]

    Do not take that chance!
    Todayís vehicles have weight sensors, occupant position sensors, seat position sensor, and on and on.
    Example: Say the weight sensor told the control module that there was less than 45 lbs or a baby in the passengerís seat at the time of the crash, it would not have deployed that airbag, but now your rescuer opens the door and gets in to help the driver, with the electrical system still in tact the control module now says there is a full size person in the seat and opens the path to the high side, if for some reason there is a short in the wiring say from a damaged wire under the hood and a charge ran back through the system, your rescuer could be in great danger.
    Remember as long as there is power the control module well continue to evaluate any change in positions and make adjustment to deploy the airbags accordingly. All we need is a feed back and we are in trouble.
    This certainly helps clear things up, but I must day it seems that the safety systems are making extrication much more dangerous to both emergency personnel and the occupants.

    Without a true gaurantee that the undeployed bags won't deploy, not getting in their path can be very difficult depending on damage and intrusion.

    It would seem that a few ports placed around the vehicle to connect a handleheld diagnostic tool that could/would read the control module would make everyones life a lot easier and safer. Of course they can't seem to put a master disconnect in so this seems to be a tall order as well.

    And while I wouldn't change our training about staying out the deployment areas this can and will come at a price to the victims who's care is delayed or otherwise compromised.

    Again forgive my lack of complete understanding of this technology, but is there a certain higher speed/impact point that all bags and all stages will deploy regardless of impact zone? These are the likely scenarios where the damage would push and redirect the airbags toward places they weren't designed to go.

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    Again forgive my lack of complete understanding of this technology, but is there a certain higher speed/impact point that all bags and all stages will deploy regardless of impact zone? These are the likely scenarios where the damage would push and redirect the airbags toward places they weren't designed to go.

    If I am understanding the question right.
    I taught for a long time that it is impossible for all airbags to be deployed in one crash. This is still true in all but that 1 in a million chances that some one posted on here awhile back and sent me pictures of, The car actually flipped and rolled 10 times hitting on all sides and therefore deployed the bags on both sides and the frontal bags.
    As a rule you will not find this, because the sensors must be hit at a certain angel, the side impact airbags will not deploy in a straight frontal crash, and the frontal airbags will not deploy in a straight side impact. But if the angle of the crash is just right say a sever frontal crash at a 45 degree angle it may be enough two alert both the frontal and the side impact sensors on that side of the car.

    To help you out as far as deployment zones remember that there is no possible way to tell if both sides of a frontal airbag have deployed, so never, never put yourself in the inflation zone.
    But, side impact airbags are different if the bag is deployed there is no more danger there is no such thing as a dual stage side impact airbag. Cut it out of your way.
    But also remember that if one side is deployed the other side will not be, because the sensor on that side has a wall built inside it that will not allow it to activate from that angle. (it is like a roller that falls into a slot, if hit from the other side the wall will stop it from rolling) (vague but gives you the idea).
    This gives you a little more working area.
    http://www.midsouthrescue.org
    Is it time to change our training yet ?

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    Hi, JorgHeck
    I have seen you on here for a while this morning, talk to us you know a lot more about this than I do!
    http://www.midsouthrescue.org
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    Thumbs up

    Lee, once again thanks. So far I'm learning that what we've been taught is still true for the most part. Like I said, now with more clarity thanks to you, the addition of more airbags is making it very difficult to stay out of the deployment areas. It truly is important to realize the deployment zones distances as large generalities could preclude one from proper immobilization of the victim or even using simple devices such as a KED. I guess we truly will have to remove the vehicle from around the patient more than ever before.

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    Just a couple of thoughts - - - some of the new cars have two batteries, by turning on the Emerg. Blinkers you can tell if both batteries are cut (if the blinkers go off with one cut you have cut them all). Also it only takes about nine volts to set off a bag.
    Stay Safe ~ The Dragon Still Bites!

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    Default Disconnect wires

    When you look at an SRS assembly it usually has a wiring pigtail (yellow?)coming off of it with a connector.

    After the electrical system is shut down, pull trim and if possible disconnect the the SRS assembly from the wiring harness at the connection. This allows the SRS assembly to stay intact. I believe this would be a better option then cutting the wires. You still have a live SRS assembly, however it is not connected to the vehicle's electrical system anymore.

    I see this occuring when we may have to remove seats, posts, or roofs where SRS assemblies are at.

    Just a thought.
    Todd D.Meyer
    Gig Harbor Fire & Medic One
    tmeyer@piercefire.org

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    Forum Member Haweater's Avatar
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    Quote Originally Posted by LeeJunkins View Post
    [COLOR="Red"]
    Todayís vehicles have weight sensors, occupant position sensors, seat position sensor, and on and on.
    Example: Say the weight sensor told the control module that there was less than 45 lbs or a baby in the passengerís seat at the time of the crash, it would not have deployed that airbag, but now your rescuer opens the door and gets in to help the driver, with the electrical system still in tact the control module now says there is a full size person in the seat and opens the path to the high side, if for some reason there is a short in the wiring say from a damaged wire under the hood and a charge ran back through the system, your rescuer could be in great danger.
    Okay, this situation leads to a question I've had for a while and didn't get around to starting a thread on..... When I put my kids' seats in our van, I make sure the kiddy seat is belted in as tightly as possible. When I tighten the seat in, there is likely more than 50lbs of force being 'felt' by the seat before the kid is even in it. Is an airbag in one of these vehicles that deploys an airbag according to weight of occupant going to smack a kid in a car seat with more force than they're supposed to according to the car manufacturer?
    I would think yes.
    G

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    Haweater,
    I am not sure of how the child carrier you are using straps in. but it is very likely not going to affect the weight sensor, because the sensor mat also measures a foot print, (Iíll try to explain).
    There are about three types of sensor mats the Semmins sensor mat is made up of many tiny strain gages that measure the weight in their area and sends a signal to the module, it then puts all of them together to form a picture of what is in the seat.(Like a foot print).
    The bladder type also forms a foot print.
    Then Bosch makes what is called the intelligent bolt or IBolt system, which is simply a strain gage built into the seat mounting bolts on all four corners, they measure the weight and the position of the weight whether there is more on one gage than on the others, this indicates the position the occupant is seating. This system also uses a seat belt tension sensor that was made just for your question it can tell if the weight is pressing on the seat or if the belt is pulling it down from being pulled tight.
    It is hard to explain without the pictures.
    Last edited by LeeJunkins; 05-14-2007 at 10:20 AM.
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    Last edited by LeeJunkins; 05-14-2007 at 11:51 AM.
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