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SRS

SRS

(OP)
Have airbags on the mind. And long before the Takata fiasco there where many people injured or killed by them. I would like to know why certain pressurized gas containers are required to have a pressure relief system or valve, as well as a fairly high strength container, where an airbag inflater can be made from almost a tin can thick steel with no relief system to protect from over pressure. I also curious why such dangerous pressure vessel is allowed to be so many inches from your face, eyes etc. while you are driving a vehicle? Weren't the first airbags deployed by CO2 gas cartridges, located away from the driver?

RE: SRS

Airbags have saved a vastly larger number of injuries and deaths than they have caused ... even the Takata ones. The current automotive ones don't use a pressurised gas container, they use a small explosive charge. When they operate as intended, there is no issue.

RE: SRS

Takata's inflator uses ammonium nitrate wafers that were manufactured without a drying agent, presumably, to save cost or simplify manufacturing. Gas cylinders, as exemplified on Mythbusters and other shows, cannot produce a sufficiently rapid inflation, since any connecting tube or hose will be limited by sonic velocity. An explosive initiator is the only practical way to an airbag to be fully inflated within the 20-30 ms necessary to prevent passenger injuries from the crash. The net result is that full inflation requires supersonic gas speeds, which can only be reliably obtained through explosions.

Interestingly, to some degree, that's how some otherwise wimpy tanks provide self-protection in the case where their armor is too thin; they have explosive reactive armor (ERA) which detonate to mess with whatever incoming anti-tank munition making contact with the ERA.

TTFN (ta ta for now)
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RE: SRS

It's not intended to be explosive. It is high burn rate. At least that's what the high-speed video of the ignition of the Takata gas generator is showing - an incremental, from one end to the other, combustion.

From what I looked at ammonium nitrate is hygroscopic and, with increased moisture, becomes resistant to burning. In the Takata devices the ammonium nitrate was in a small cylinder with periodic vent holes. As the fuel burns the gas was ejected through the incrementally exposed holes. It looked to me like, in the videos showing detonation, that contaminated/compromised fuel wasn't completely burning but instead was ending up plugging the holes - creating a tiny pipe bomb by increased pressure forcing an increase in heat causing bulk detonation.

Research into ammonium nitrate bombs was done by the US military to determine how long an IED based on ammonium nitrate would remain a threat when left exposed to the weather. They concluded that degradation from moisture would render them ineffective at some point.

In any case, the addition of a pressure relief might not be possible, but what is certainly possible is designing a reliable and safe rupture mode that doesn't result in generating shrapnel or a containment/deflection system to guide fragments away from the throats and faces of occupants of cars. I've seen enough explosive-forming of metal and explosive bolts to believe that this is possible. Not doing so is likely to save a dollar or two on the manufacturing cost of the airbag - the likely reason they don't. Note that using ammonium nitrate itself was to save a similar amount of money.

This video - notice the sputtering and then how gas venting slows. https://www.youtube.com/watch?v=eBjxprHh3QI

RE: SRS

(OP)
I'm worried about the short women in my family. One has to sit with her stomach almost up against the steering wheel. What I read is the bags can create about 2k lbs of force. Like everything I think there is a better way, just not as cheap.

RE: SRS

The airbag design is supposed to limit the force applied based on size, venting, and strength.
Small and/or light occupants are a real issue.
There are a number of newer implementations that actually alter the inflation based on the sensed weight in the seat (usually just high and low).
I have no idea how effective they are.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: SRS

While a small sample, a co-worker of mine, a fragile 70+ year old with really bad driving habits was in two crashes about a year apart. He was under 5 foot tall. In the first crash, no airbag in the car, the shoulder belt broke his collar bone and he wore a sling for a long time. In the second, the replacement car's airbag deployed and he was unhappy because the fabric gave his face a rug burn. I don't know the exact level of collision in either case, but it was an interesting contrast.

RE: SRS

(OP)
Great. Now what kind of propellant was used to replace the faulty propellant in the takata airbags? I thought I remember hearing it was the exact same stuff only newer? If so then its only a matter of time and the same ole thing will repeat itself. So now I ask how important are your eyes to you? Will Z87 safety glasses and shields stop the projectiles? I don't think so. There needs to be some serious engineering on these systems. The tin can pressure vessel has to go.

RE: SRS

Blindness from flying shrapnel has never been a widespread issue, not even with Takata airbags.

If the Takata thing bugs you, just get one with airbags from a different supplier. Autoliv is another really common one.

RE: SRS

(OP)
What are the propellants used in the various manufacture airbags now? I suppose safety took a back seat because of some other perceived notion, because we sure didn't hear about inflaters blowing up in the early days of airbags.
So a particular car maker recalls for the 2 frontal airbags, and the other 4 are ignored? Does that mean they don't have the dangerous ammonium nitrate that the other 2 have or had?

The blindness issue, there have been many eyes ruined from them, more than deaths.

RE: SRS

Appears that ammonium nitrate is what Takata uses. It appears that there are several other choices, the main one being a reaction between sodium azide and potassium nitrate.

RE: SRS

The greatest worry is areas with long periods of very high humidity. However, even with the very unfortunate deaths and injuries which should have been avoidable, Takata found itself in a classic squeeze.

The product, on delivery, was fine - cost effective and reliable. It was only after years of exposure, which might not have been well simulated in accelerated heat w/humidity tests, that the problem was spotted. The squeeze came in thusly - if Takata let on that this was a problem they would not only have to produce all the orders they currently had, get new orders to continue an income, but also spool up manufacturing to replace all inflators they ever made. I think few companies could survive that, plus they would have to somehow also develop an entirely new inflator that could not have any similar defect as both the replacement, the current production, and for future contracts in what would likely be a year before they got cut off by everyone.

Worse, major auto makers knew about these problems, which is what prompted the Takata inquiries, and those companies kept it quiet as well.

I see from https://en.wikipedia.org/wiki/Takata_Corporation that Takata had previously been involved with seatbelt failures and, again, the major makers knew about the problems and kept silent.

In the grand scheme of things, airbags do not guarantee survival; they simply significantly reduce the chances of death or serious injury. And even with the deaths from the shrapnel included, the overall reduction in deaths and other injuries was apparently a very large net positive. I would like that the airbag inflators had been designed to have a safe mode for over-pressure rupture rather than uncontrolled fragmentation.

In looking at some Chinese inflator manufacturer pages, they list a 15 year lifetime for their inflators. It would be nice to know what happens at the end of that time. The price of the inflator is around $20, but I expect that this is not replaceable individually in the airbag system.

RE: SRS

(OP)
So then for us that wish not to have rock blasting stuff inches from our faces, all auto manufactures should then offer a safer alternative propellant inflator, on request. Or all airbags should have a standard SAE inflator opening and bolt pattern just like an SAE transmission PTO opening and bolt pattern so we could shop around for a safer inflator.
Its just so hard to believe the ignorance of this whole issue. How often are these things removed from various year cars and tested? Some of the recalls are now many years ago. I personally don't care to gamble.

RE: SRS

The design of those airbags is tailored to the design of the vehicle and its interior around them. Unless you are going to lock in the design of all vehicles so that they are all the same shape and size with identical interiors and seats, AND lock the whole industry out of all further developments, an SAE standard uniform airbag is not going to happen.

Vehicle designs are homologated with the airbags specified for them. You can't just swap to a "safer alternative". This is one of the things that trapped Takata and the manufacturers who used them. They knew the design flaw (which accelerated testing could not have found) but they couldn't change the design of the homologated airbags including their inflator without redoing the homologation of all of the affected vehicles, and redoing crash testing of dozens of 10 year old vehicle designs that are no longer in production is not going to happen. The recalls simply replaced like for like. Maybe minor changes to address moisture intrusion could be done but nothing could be changed that affected its performance.

If you don't like this then buy a vehicle with airbags from a different supplier.

RE: SRS

Quote (enginesrus)

I personally don't care to gamble.

You are more likely to hit the powerball than you are to be killed by airbag shrapnel.

RE: SRS

The "original" TRW airbags used straight sodium azide (the nitrate is just used to initiate the decomposition reaction of the azide). Azide, in addition to being explosive, is a very toxic compound (inhalation of a few tenths of a gram will kill you). The risk to automobile passengers is fairly low (because normally most of the stuff is reacted before it gets out of the airbag), but the risk to the people assembling the bags wasn't. The major manufacturers have thus moved away from it, to "safer" propellants...which have issues of their own.

RE: SRS

(OP)
Powerball? Not so much as one number there, but with a dangerous airbag? Well this is the kind of gamble that I would win at.
So NHTSA must care more about the auto manufactures than the folks that get stuck with ill designed junk that may seriously injure or kill them, sort of shows what that organization is all about.

https://www.autoblog.com/2020/01/14/takata-replace...

Supposedly Takata has not used Ammonium Nitrate in the inflators since 2019? And no one cares about what happens when the salt and rice congeal in the last transplanted non azide inflators that are posed in many vehicles on the road and ready to redesign your face.

RE: SRS

Real world experience over the last couple of decades has been that in terms of occupant safety, the benefits outweigh the risks by an enormous margin.

RE: SRS

Quote (BrianPetersen)

Real world experience over the last couple of decades has been that in terms of occupant safety, the benefits outweigh the risks by an enormous margin.

Clearly your real world experience must be wrong, because engineers have not correctly designed anything in any industry since 1949

RE: SRS

The original airbags, in addition to being hazardous to assemble were also very likely to break bones in your face (nose, cheek, orbital).
A friend's father experienced this, but he was glad since the accident would have been fatal otherwise.
But even the early fairly crude ones were significantly reducing fatalities.
As crumple zone designs improved and they were able to better dissipate the energy of impact and then use more reasonable inflation forces.
I have only been hit by an airbag once. Ironically it wasn't a serious accident. I won't say that it was fun, but it was no big deal.
More of a suprise than anything, it happens incredibly fast. No burns or scrapes, just a few bruises. Didn't even break my glasses.
Cravat, I am large and tall (6'1", 200lb) and I sit way back from the wheel.

Our reliance on a technical solution over behavioral ones in a sign of our times.
Virtually all collisions are the result of driver errors.We are so afraid to impose any restrictions on drivers because the privilege of driving has come to be seen as a right. Granted, we have built a society in US where driving is a necessity of life in most places which compound the problems.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: SRS

(OP)
EdStainless, very true. I'm close to 70, as a kid I rode in the back of pickup trucks, never ever had a seat belt on, sat in the front seat, cars had a nice hard steel dash with no padding. I have no qualms about not having an airbag in front of me in a car. I have been in a few instances where speeding people were in my lane passing another car in hidden corners, and freeway late night wrong way drivers. The cure? To stay alert and always have a plan of what you will do.
I will take the no bag option any day over the dangerous inflator.
Airbags do not protect from crushing accidents, they only help keep your head from going through the windshield. Did you ever see the video of the test driver that would daily crash into a wall at 50 to 60 mph, with no seat belt? The solution is simple, airbags where just fine until takata put ammonium nitrate in the inflators. And there are still many unsuspecting car owners and drivers that THINK its all fine and dandy now because of the recalls. NOT TRUE.

RE: SRS

I also grew up pre-safety, and I am glad for airbags.
More cars packed onto roads with much poorer drivers.
I'll take the infinitesimally small risk of the airbag over the very real risk of traffic.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: SRS

I also grew up and learned to drive pre-safety-devices, but I also work in the auto industry on the supplier side. Modern vehicle safety systems are an integrated package, No, the airbag alone does not protect from crushing situations, but that's what the safety-cage construction in modern unibodies is for, which greatly reduces the possibility of impacts deforming the part of the bodyshell around the occupants by enough for that to be a problem. That safety cage, plus better brakes, and better suspension, and better tires, and ABS-ESP, and attention paid to where your body parts are potentially going to strike the interior of the vehicle, plus the airbags, plus a lot of engineering into the crumple zones, adds up to a safety package that is enormously better than it was in the 1980s or before.

I don't like the impending intrusion of automated systems on the driver's experience, either, but there's a fair argument that what's on the market now (before The Powers That Be impose automated systems that force the vehicle to comply to all posted speed limits, no matter how ridiculously low they may be) strikes the best possible balance between safety and enjoyment. If it all goes self-driving then the car becomes a mere appliance.

It so happens that the car that I drive today (modern Fiat 500) is quite close to the same size as the car that I learned to drive in (1970s-era Honda Civic). I'm pretty sure that if there were to be a hypothetical collision between these two cars, the modern one would go right through the old one, obliterating the old one in the process along with everything inside it, and the smart airbags in the new one might not even fire, due to the collision being not severe enough to warrant setting them off. That experiment has been done, although with vehicles in a bigger size class ... it'll be the same idea, though: https://www.youtube.com/watch?v=vRxLlFm3VUA

RE: SRS

While I agree in general, whenever you see these old car vs new car crashes they usually base it on model for model, or sometimes size for size. That, frankly, is rigging the experiment, it should be mass for mass. For instance an Espace 5 could weigh 1805 kg curb, the original was 1500.

Cheers

Greg Locock


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RE: SRS

Quote (enginesrus)

I will take the no bag option any day over the dangerous inflator.
Airbags do not protect from crushing accidents, they only help keep your head from going through the windshield. Did you ever see the video of the test driver that would daily crash into a wall at 50 to 60 mph, with no seat belt? The solution is simple, airbags where just fine until takata put ammonium nitrate in the inflators. And there are still many unsuspecting car owners and drivers that THINK its all fine and dandy now because of the recalls. NOT TRUE.

I really don't know why I bother responding to your posts anymore. Maybe it's just my sense of the importance of posterity.

Anyway:

https://injuryfacts.nsc.org/motor-vehicle/historic....

https://en.wikipedia.org/wiki/Motor_vehicle_fatali...

https://www.iihs.org/topics/fatality-statistics/de...

As usual, the data indicates that the current rates of traffic fatalities per vehicle and per mile are not only lower than they were in the 70s, 80s, or 90s - they are significantly lower.

Notice that the entire Takata airbag recall incident did not even cause a blip in the aggregate data.

RE: SRS

(OP)
I am not anti airbag. I am anti ammonium nitrate propellant in the inflator. I just want to be able to replace them with something safer. Recalled vehicles still have the ammonium nitrate. Fragmenting airbags are still with us. That is the issue here. Every time you turn the steering wheel on an older car you run the chance that the airbag will go off. Many times airbags have deployed for no apparent reason, and if your the lucky one with the bad inflator that is ready to spit metal at you then? Give me all the statistics you wish, to the many injured people those all mean absolutely nothing.
And curious why would anyone quote Wikipedia?

The real information.
https://www.youtube.com/watch?v=T1-d5emalpI

RE: SRS

Quote (enginesrus)

And curious why would anyone quote Wikipedia?

The real information.
<insert random YouTube video>
The irony is thick with this one...

Dan - Owner
http://www.Hi-TecDesigns.com

RE: SRS

I wasn't going to point that out.
When I go to Wiki I usually start by looking at the references. If they are a bunch of real sources I'll real it.
No references for youtube is there?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: SRS

(OP)
And you never even looked at who the presenter was in the youtube video did ya? It is not some phony agenda seeker on Wikipedia.

RE: SRS

Since that report included the Beirut explosion of ~3,000 TONS of ammonium nitrate that was co-located with an unknown number of tons of black-powder fireworks that were the initial out-of-control fire source I'd say it's simple sensationalism at its worst. Ammonium nitrate is typically a fertilizer and it's difficult to get it to explode so anyone calling it an "explosive" is fear mongering.

I don't know what happened to Sharyl Attkisson. After 21 years she quit national news to join the intentionally politically active Sinclair Broadcast Group.

RE: SRS

(OP)
There is nothing sensational when your airbag inflator fragments into small sharp projectiles and redesigns your face is there?

RE: SRS

2
That's why Takata is in the midst of a recall. But in the meantime ... the number of actual such incidents, which actually inflicted greater injury than what would have happened in the absence of any airbag at all, is vanishingly small compared to the number of lives that have been saved by airbags over the years, including Takata airbags. If you have a car with Takata airbags and you get the recall notice, get it done. Otherwise, the risk is so remote that it is not worth fretting about.

RE: SRS

Quote (enginesrus)

There is nothing sensational when your airbag inflator fragments into small sharp projectiles and redesigns your face is there?

When the incident rate is so low that the probability of this happening to any individual person is so small as to not even appear in signal beyond noise, no. It's not really sensational. Notable, perhaps. But sensational? Cause for your apparent hysteria? Certainly not.

Highest occurrence rate for fatalities (allegedly) caused by faulty Takata product appears to be 2016, when there were 7 deaths globally. In 2016 there were roughly 1,350,000 traffic fatalities globally.

This means that in 2016, again the highest rate of incidence, takata airbag failures represented .0005% of traffic fatalities globally.

In that same year, in the US, there were a grand total of 2 fatalities. In 2016, in the US, there were 7,277,000 reported traffic accidents per NHTSA. So your odds of being killed by a Takata airbag failure in 2016 were 1 in 3,638,500.

For comparison:

Odds of being killed in a shark attack (annual average): 1 in 3,748,067

Odds of being killed by a lightning strike: 1 in 79,746

Odds of being killed in a railroad accident: 1 in 156,169

Odds of being killed in an accident involving fireworks: 1 in 340,733

So, yeah. This isn't a major concern about which anyone should be terrified.

RE: SRS

(OP)
The main problem with the recalls is. They were just putting new of the same thing in at the time. NHTSA knows that as well, and they are in a lets wait and see what happens holding pattern, that is the problem.
And all those ODDs mean nothing, being killed? I personally don't want to be maimed, especially sight, nor do I want that for my family members either. I don't gamble, if you wish to go ahead.
Logic says get the stinking ammonium nitrate out of the inflators, period.

I would like to know how dangerous the non frontal inflators are? This particular car has 4 more.

RE: SRS

Drive with safety glasses and a kevlar scarf. These will also be helpful in the far more likely event someone chucks a rock off an overpass or a deer says "hello" from a leap across the highway.

RE: SRS

Quote (enginesrus)

I don't gamble

Yes you do. Every time you get in a car, a train, a plane, or a boat. Any time you leave the house, and any time you DON'T leave the house for that matter.

Quote (enginesrus)

I would like to know how dangerous the non frontal inflators are? This particular car has 4 more.

You could find that out if you were willing to do some reading into those statistics you don't trust or believe.

If you read them you'd discover that, like the frontal inflators which apparently terrify you, they are not really dangerous at all.

RE: SRS

Now a pre-frontal inflator, that would really sting!

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: SRS

(OP)
https://www.businessinsider.com/senators-are-looki...
One of many photos of people injured.

((((You could find that out if you were willing to do some reading into those statistics you don't trust or believe.))))

(((((If you read them you'd discover that, like the frontal inflators which apparently terrify you, they are not really dangerous at all.))))

Give me some links that show what happens with the other airbags that have an ammonium nitrate failure, I'll be very happy to read them.

RE: SRS

Quote (Cnet article linked by enginesrus)

NHTSA said there are no reported ruptures in desiccated units and drivers do not need to take any action right now. In addition, the government is also looking at a separate propellant Takata used. The time in service for this propellant is shorter than the others, and NHTSA said it will need to study it further. Right now, this other propellant does not show signs of degradation.

So........ just fear mongering.

Do you just run around looking at every consumer product you own in terror?

Quote (enginesrus)

Give me some links that show what happens with the other airbags that have an ammonium nitrate failure, I'll be very happy to read them.

Researching failures that have not happened, to assuage your completely irrational fear, is not my task to complete. If you want to just walk around screaming at the sky for being blue, and wasting time being a drain on this forum, that's on you dude.

RE: SRS

(OP)
I thought personal attacks where not allowed on this site?

RE: SRS

It's not a personal attack - its commentary on your posting style and history. You contribute nothing. You do it in every thread you start. You post some question, get reasonable responses, insult the general practice of engineering, tell everyone how they did it better in 1929, and ignore all the information posted in response. Then disappear until you, as far as I can tell, decide you have some brilliant new lesson you're going to teach the engineers of the world. It's a tired bit.

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