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The insignificance of "Drain Times"

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  • vehext
    replied
    Capacitors store electrical energy. The question is how long and I sure have seen a lot of thoughts out there. I've had an electrical engineer tell me a capacitor cannot hold a charge longer than 90 seconds.

    I recently dug up and very old strobe light bar from our attic... thing has been there for years and was coated with dust. As we disassembled it to get some needed parts, it shocked the crap out of me. Electrons don't seem to mind hanging around until they have a place to go. So much for drain time.

    Our SOP calls for personnel to stay out of deployment zone anytime they are working around a loaded bag. The OMD's have signed off on using rapid extrication technique so our guys are not in the danger zone any longer than they need to be. We don't use equipment designed to stop/delay air bag deployment... NHSTA has issued an advisory against their use and steering wheel rings have no strength anyway. Cutting battery cables prevents the use of such devices as seat position, windows, etc.

    Don't trust capacitors which means don't trust loaded airbags. Keep in simple.

    JEB

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  • nmfire
    replied
    Originally posted by ROOFIT View Post
    I'm just going to throw two cents in here. Almost all vehicles have emergency 4-way flashers, turning them on after doing the 360 scene safety survey if possible will give everyone a visual that the vehicle has power.
    This is a good idea when it works, but it isn't something that can be relied on. If you see the flashers, you know the car has power. But you can't assume it doesn't have power if the flashers aren't on. There are a hundred reason the flashers may not work even if the battery is still connected.

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  • Lifeguard911
    replied
    Originally posted by THEFIRENUT View Post
    Maybe Lifeguard911 meant to say that it would be impossible to open the door WITHOUT a spreader.

    Thanks for the correction. That is what I meant. I learned thi from personal experience with my own truck after it sank in a flood (another story)!


    "Umm. I'm pretty sure that the status of the door locks is irrelevant during any phase of extrication. Its not like the door welds itself shut when you engage the child locks."
    __________________
    What I was trying to point out was that if you check the doors first before cutting the power, you will not have to do extrication.
    Last edited by Lifeguard911; 04-30-2007, 01:54 PM.

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  • ROOFIT
    replied
    I'm just going to throw two cents in here. Almost all vehicles have emergency 4-way flashers, turning them on after doing the 360 scene safety survey if possible will give everyone a visual that the vehicle has power. Airbags are here to stay and new versions of occupant safety equipment will make our jobs more difficult as time goes forward. Safety is always a concern but we must still manage the risks involved best we can with training, knowledge and experience. This extrication business sure was less stressful without all of this modern day techno safety geek stuff.

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  • THEFIRENUT
    replied
    Originally posted by Lifeguard911 View Post
    On cars with electric door locks and child safety locks on the back doors, cutting the power will make it impossible to open the door with a spreader.
    Maybe Lifeguard911 meant to say that it would be impossible to open the door WITHOUT a spreader.

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  • nmfire
    replied
    Originally posted by Lifeguard911 View Post
    Just a quick hint before cutting the power to the vehicle- check all the doors to see if they will open normally by using the door latch. On cars with electric door locks and child safety locks on the back doors, cutting the power will make it impossible to open the door with a spreader.
    Without power and with the child safety locks engaged, you cannot open them manually from the inside or use the unlock feature by the driver to open the locks. Locked doors of course cannot be opened from the outside either without force.
    Just a quick check to open the doors manually can save you lots of time later.
    Umm. I'm pretty sure that the status of the door locks is irrelevant during any phase of extrication. Its not like the door welds itself shut when you engage the child locks.

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  • firenresq77
    replied
    Originally posted by Lifeguard911 View Post
    On cars with electric door locks and child safety locks on the back doors, cutting the power will make it impossible to open the door with a spreader.

    I beg to differ here........ A child lock is not going to keep spreaders from opening the door.......

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  • Lifeguard911
    replied
    Just a quick hint before cutting the power to the vehicle- check all the doors to see if they will open normally by using the door latch. On cars with electric door locks and child safety locks on the back doors, cutting the power will make it impossible to open the door with a spreader.
    Without power and with the child safety locks engaged, you cannot open them manually from the inside or use the unlock feature by the driver to open the locks. Locked doors of course cannot be opened from the outside either without force.
    Just a quick check to open the doors manually can save you lots of time later.

    Leave a comment:


  • nmfire
    replied
    The "backfeeding accessory" thing is true. *Most* modern electronics you plug into a lighter plug will not do this. However, there are plenty of devices that can and will do it and I have witnessed it myself.

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  • hrtrescue10
    replied
    I agree with the general idea behind this conversation. Regardless if it is beyond the bleed down of the capacitor or not, the airbag system is just as dangerous. I have always taught in my classes that bleed down is irrelevant. Cutting thru an inflation cylinder is just as big a risk as setting off a bag. Too many variables, static and otherwise can set off the bag long after the bleed down time.
    I am not saying anyone is wrong, if anything, misinformed, but I am still not convinced on the "backflow" of charge from a cell phone charger. I have had automotive engineers tell me both ways and show evidence to support both sides. Real ones, not internet educated firehouse surfers and overpaid lectors who have less time on tools than the folks they are talking to. Our job is to extricate, and move the patient to the hospital, not to spend time trying to unplug a laptop, that I have to put myself in harms way just to get to.
    The idea of the books, is to help, on occasion, guide you through safe extrication.
    I agree the bleed down time of a capacitor is the last thing I would look up. However, it is not that hard to identify a vehicle. A photo of a wrecked vehicle from 10 feet away on a powerpoint is poor example. I have seen the "trick" used by someone trying to justify his ideas in a $350 dollar a person class that others do for free. Gotta have some way to sleep at night after cashing a $40,000 paycheck of taxpayer money for two days work.
    I, along with many others in the field have used the book to identify hazards that we just did not know about or were not quite sure. It takes less than a minute if you learn to use it properly. I am not sure about the moditech program, but if it can be sold for the kind of money that it is, it must have some good info also.
    "old school" which someone mentioned above is just that, old. I am as old school as they come, but that is also the mentality that gets folks hurt. Who would have thought 10 years ago that we would have been talking on the internet about extrication? A lot of you could no type 10 years ago, some still can't. We learned it was the best way to share ideas quickly and efficiently for a large audience.
    The same goes for reference books and computer programs about vehicle information. The same for advanced design rescue tools. The same for lightweight, cooler gear.
    Lets use the "old school" as our basis, and bring it forward with technology. Saying stupid things only hinders those we are trying to teach by allowing them to form false ideas and justify shortcuts that get them hurt.

    Like Lee says, is it time to change our training. Well, it is way past time to change our thinking, if you can't, then you need to find a seat in the back and let someone else take over.

    Leave a comment:


  • dragonfyre
    replied
    Originally posted by hrtrescue10 View Post
    I guess Ron forgot about the Rescuer's Guide put out by Holmatro, funny..

    The newest one at FDIC had thru the 2007 model, in print and CD. They said they will be updating it yearly. The drain times were listed as well as so much other info. The $200 price makes it a bargain when compared most of the other stuff I have looked at on the market.
    I really liked the CD version.

    There's only one problem with that or the Crash Recovery System computer program:

    If you are not in the automotive field can you, at 0300, in the dark, still wiping the sleep out of your eyes, tell if that car with the smashed in front end is a 2000 or a 2004 "Whatever ZXP-20"? There may be a difference in the number of bags in the car. Say they added side curtains and dual-stage bags for the 2003 MY.

    As Ron & I both teach, stay with the basics. Find your electrical source, disconnect it, keep your 5-10 distances, do an external and internal 360. Keep your wits about you and don't place anything in the path of deployment.

    Also, don't forget to unplug anything the patient may have plugged into the power ports (Cigarette lighters). The batteries in a laptop have enough power to run back through the system and provide enough voltage to deploy the bags.

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  • mcaldwell
    replied
    Originally posted by Bones42 View Post
    In the time it takes to find the information in the book/cd, the capacitor has drained.

    That's another example of our old-school Rule of Thumb answers. By the time you thumb through the book to find the answer, the emergency is over.

    I don't think were suposed to use those anymore.

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  • cardoc
    replied
    Originally posted by domi411 View Post
    Somebody talk to me about connect the positive and the negative together to drain all the power, what to you think about that????

    I am in the automotive field and an Instructor in Missouri. This will do nothing for drain times. The reason: The computers. The Air bag module has a capasitor - right. If in a wreck the battery would short. The capasitor would drain. Possibly to quickly. So they put diodes in. Think of them as a gate. This keeps the voltage from draining out the old fashion way like connecting the cables. This inables voltage to stay in the DERM module longer and be able to allow the system the voltage it needs when in a wreck with the loss of the battery as its power source. Alan

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  • LeeJunkins
    replied
    Originally posted by nmfire View Post
    The way I used to teach extrication for the last several years was to first talk about drain times and then tell everyone to avoid the deployment zones at all times. It all of a sudden occurred to me that "who cares what the drain time is". If the 5 minute clock winds down, am I going to recommend people then sit on the steering wheel while collaring the patient? NO! I don't care if the battery left the vehicle while it was rolling over and is now in a tree 500ft down the road. Stay out of those airbag deployment zones ALL THE TIME.
    Stay out of those airbag deployment zones ALL THE TIME.

    This is a must, because as we have seen even without a battery, static electricity or feed back from other sources can set one off.

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  • nmfire
    replied
    The way I used to teach extrication for the last several years was to first talk about drain times and then tell everyone to avoid the deployment zones at all times. It all of a sudden occurred to me that "who cares what the drain time is". If the 5 minute clock winds down, am I going to recommend people then sit on the steering wheel while collaring the patient? NO! I don't care if the battery left the vehicle while it was rolling over and is now in a tree 500ft down the road. Stay out of those airbag deployment zones ALL THE TIME.

    Leave a comment:

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