Aging Air Bags and Seat Belts
12-05-14, 10:57 AM
#1
Aging Air Bags and Seat Belts
Has anyone looked into the shelf life of the air bag systems on our vehicles as well as the seat belt systems--these obviously do not last forever. I was just wondering if anyone has looked into this issue or has some knowledge about replacement of these systems.
12-05-14, 01:16 PM
#3
Seat belts are designed to last as long as they are in good condition. That means if the edges are fraying they need to be replaced. You will not find a defined life span anywhere as they could last 5 years or 50. You just have to inspect them.
As for air bags, I have no idea. I took mine out.
As for air bags, I have no idea. I took mine out.
12-05-14, 09:58 PM
#4
^^I think as far as the seat belts are concerned, I was more interested in the locking mechanism. My seat belts hardly retract anymore the mechanism is so balky. I debate whether the locking mechanism is truly going to work when called upon. Similarly for the air bag, does it start to disintegrate after 2 decades? I would hate to have dust blown into my face when it is also called upon to operate.
12-06-14, 06:31 AM
#5
I happen to know a bit about this subject. This will be a bit long, but stay with me;
The bag itself is a machine woven Nylon 6,6 fabric material. Nylon does age, and for that reason, DuPont who makes most of the airbag materials, readily states that they have a "working lifespan of 15 years" due to the bag fabric degradation. The nylon bag may actually outlast the 15 year lifespan given by DuPont, but factors such as humidity, heat, etc are uncontrollable, so they blanket the 15 year life onto them.
Nylon 6,6 does degrade with exposure to UV and to moisture. UV not being the real problem, as the bags are kept tucked away from sunlight for most all of their working life. Moisture can be the real issue- flood damaged cars and exposure to moisture like that will degrade the nylon over time, and especially if it stays rolled up and has no way to dry itself out, it may begin to weaken the woven bag material and wash the talc lubricant off the bag, so when it does need to fire, it does not unfurl evenly and it then fails to protect you. This is why I look at flood damaged cars with a grain of salt.
Everything you asked for, is right here in this document from DuPont:
http://www2.dupont.com/Automotive/en...bagfabrics.pdf
Quite often, the bag is rolled up and coated in an inert, non-dangerous talc powder simply to stop the bag sticking to itself over the years, and acting as a bit of a 'dry lubricant' to get it to unfurl rapidly, quickly and correctly after being bunched up and stored for so long.
The FD uses an older inorganic sodium azide chemical propellant type system. 130 grams of sodium azide produces about 66.8 liters of nitrogen gas. Nitrogen being inert, this is ideal to inflate a bag quickly.
The sodium is very reactive, but many people are scared that the bags will deploy in your face if you're working close to them or you bump or tap the dash where the bag lives. This is largely a myth. The sodium azide propellant chamber contains an igniter chemical, which MUST have an electrical charge added to it, in order to fire off and get the sodium to begin the chemical reaction of 2 NaN3 --> 2 Na + 3 N2. Simply bumping or hitting the dashboard near the proximity of the bag will not trigger it in 99% of cases where the airbag system is correctly operating. It needs that electrical charge to begin the chemical reaction.
Manufacturers tend to add the frightening looking yellow warning signs around the car, mainly as a means of indemnifying themselves to idiots who may be tempted to play with the system or attempt to service or open it up themselves. If you make it scary, you will deter people who don't know enough to not be afraid of it. Sort of a "Well, we did tell you not to play with it" legal sticker in case Bob happens to go digging around in there and then tries to sue the car company later, when he crosses two wires and shoots a screwdriver into his neck inadvertently.
The sodium azide propellant should have a stored service life longer than the bag material, if stored in its sealed canister and nothing goes wrong. By that, I mean it does not get heated (275C and above, and it combusts on its own). It has an inbuilt anti-bacterial action, so in theory, no bacteria or other junk should begin to grow inside its container at any stage, and this helps its longevity. If it gets wet, it will form hydrazoic acid, a very toxic and very explosive gas. The containers in the airbag system for the sodium azide are designed to prevent any of these reactions from happening, and if the airbag is heated in a fire, it may deploy spontaneously when the sodium gets heated past the 275C flash point, without any electrical ignitor input at all.
So back to your original question- these cars are old, how safe are the airbags?
1. Well for one thing, you are definitely not going to get "dust blown in your face" if the old airbag fires. It is either going to deploy, or it is going to fail to deploy, for the reasons stated above.
2. If it deploys, it will deploy correctly. Or the bag may be stuck to itself or degraded due to past moisture (flood damage, etc) and it may not unroll properly, and you may or may not die due to this.
3. If something was to go wrong with the sodium azide propellant, you would know about it. The sodium is very reactive, and if moisture or heat was to interfere with it, you would see some pretty special things going on inside the car, long before the bags deployed. The fact that all remains quiet in your interior and there is no airbag light lit up on the dash, is a good indicator that the propellant is OK and the electrical firing system is OK. No news is good news.
The oldest FD being 1992 (my car) is now 22 years old. That is well past the DuPont rated service life of the airbag. To still have an in-service rated airbag system, your FD needs to be no older than about 1999. But none of the FDs in the USA are that young. So bluntly, every FD RX-7 in North America with an airbag, is past its rated service life now.
That is not to say the system will fail you. But it is outside of its rated lifetime, so no guarantees. Personally, if the car has not been exposed to a flood or lake excursion event, I would still believe the bags would inflate and operate. Because we see a lot of 1997, etc Toyotas, Nissans, BMWs, etc every day around the world (that have dormant bags that are outside their rated service life) deploy in traffic accidents and the vast majority still operate as designed.
I have a 2001 Holden (Chevrolet to you) Caprice V8 sedan that does my daily driving duty in place of the RX-7 now. The airbag system and car is now 13 years old. It uses frontal bags in the steering wheel and dashboard, as well as side impact bags in the seats themselves. In an accident, the side seams of the seat bolsters are supposed to split open, and a full length head-to-lower-torso body side impact bag is supposed to inflate, protecting your entire side torso and head from injury and head impact to the front door window glass.
Many people who get in that car as passengers, do not know what is primed and ready, inches away from the side of them, inside the seat they are bumping and jostling around in, getting in and out of, every day. Yet people are scared of bags in the dashboard or steering wheel going off...
The bag itself is a machine woven Nylon 6,6 fabric material. Nylon does age, and for that reason, DuPont who makes most of the airbag materials, readily states that they have a "working lifespan of 15 years" due to the bag fabric degradation. The nylon bag may actually outlast the 15 year lifespan given by DuPont, but factors such as humidity, heat, etc are uncontrollable, so they blanket the 15 year life onto them.
Nylon 6,6 does degrade with exposure to UV and to moisture. UV not being the real problem, as the bags are kept tucked away from sunlight for most all of their working life. Moisture can be the real issue- flood damaged cars and exposure to moisture like that will degrade the nylon over time, and especially if it stays rolled up and has no way to dry itself out, it may begin to weaken the woven bag material and wash the talc lubricant off the bag, so when it does need to fire, it does not unfurl evenly and it then fails to protect you. This is why I look at flood damaged cars with a grain of salt.
Everything you asked for, is right here in this document from DuPont:
http://www2.dupont.com/Automotive/en...bagfabrics.pdf
Quite often, the bag is rolled up and coated in an inert, non-dangerous talc powder simply to stop the bag sticking to itself over the years, and acting as a bit of a 'dry lubricant' to get it to unfurl rapidly, quickly and correctly after being bunched up and stored for so long.
The FD uses an older inorganic sodium azide chemical propellant type system. 130 grams of sodium azide produces about 66.8 liters of nitrogen gas. Nitrogen being inert, this is ideal to inflate a bag quickly.
The sodium is very reactive, but many people are scared that the bags will deploy in your face if you're working close to them or you bump or tap the dash where the bag lives. This is largely a myth. The sodium azide propellant chamber contains an igniter chemical, which MUST have an electrical charge added to it, in order to fire off and get the sodium to begin the chemical reaction of 2 NaN3 --> 2 Na + 3 N2. Simply bumping or hitting the dashboard near the proximity of the bag will not trigger it in 99% of cases where the airbag system is correctly operating. It needs that electrical charge to begin the chemical reaction.
Manufacturers tend to add the frightening looking yellow warning signs around the car, mainly as a means of indemnifying themselves to idiots who may be tempted to play with the system or attempt to service or open it up themselves. If you make it scary, you will deter people who don't know enough to not be afraid of it. Sort of a "Well, we did tell you not to play with it" legal sticker in case Bob happens to go digging around in there and then tries to sue the car company later, when he crosses two wires and shoots a screwdriver into his neck inadvertently.
The sodium azide propellant should have a stored service life longer than the bag material, if stored in its sealed canister and nothing goes wrong. By that, I mean it does not get heated (275C and above, and it combusts on its own). It has an inbuilt anti-bacterial action, so in theory, no bacteria or other junk should begin to grow inside its container at any stage, and this helps its longevity. If it gets wet, it will form hydrazoic acid, a very toxic and very explosive gas. The containers in the airbag system for the sodium azide are designed to prevent any of these reactions from happening, and if the airbag is heated in a fire, it may deploy spontaneously when the sodium gets heated past the 275C flash point, without any electrical ignitor input at all.
So back to your original question- these cars are old, how safe are the airbags?
1. Well for one thing, you are definitely not going to get "dust blown in your face" if the old airbag fires. It is either going to deploy, or it is going to fail to deploy, for the reasons stated above.
2. If it deploys, it will deploy correctly. Or the bag may be stuck to itself or degraded due to past moisture (flood damage, etc) and it may not unroll properly, and you may or may not die due to this.
3. If something was to go wrong with the sodium azide propellant, you would know about it. The sodium is very reactive, and if moisture or heat was to interfere with it, you would see some pretty special things going on inside the car, long before the bags deployed. The fact that all remains quiet in your interior and there is no airbag light lit up on the dash, is a good indicator that the propellant is OK and the electrical firing system is OK. No news is good news.
The oldest FD being 1992 (my car) is now 22 years old. That is well past the DuPont rated service life of the airbag. To still have an in-service rated airbag system, your FD needs to be no older than about 1999. But none of the FDs in the USA are that young. So bluntly, every FD RX-7 in North America with an airbag, is past its rated service life now.
That is not to say the system will fail you. But it is outside of its rated lifetime, so no guarantees. Personally, if the car has not been exposed to a flood or lake excursion event, I would still believe the bags would inflate and operate. Because we see a lot of 1997, etc Toyotas, Nissans, BMWs, etc every day around the world (that have dormant bags that are outside their rated service life) deploy in traffic accidents and the vast majority still operate as designed.
I have a 2001 Holden (Chevrolet to you) Caprice V8 sedan that does my daily driving duty in place of the RX-7 now. The airbag system and car is now 13 years old. It uses frontal bags in the steering wheel and dashboard, as well as side impact bags in the seats themselves. In an accident, the side seams of the seat bolsters are supposed to split open, and a full length head-to-lower-torso body side impact bag is supposed to inflate, protecting your entire side torso and head from injury and head impact to the front door window glass.
Many people who get in that car as passengers, do not know what is primed and ready, inches away from the side of them, inside the seat they are bumping and jostling around in, getting in and out of, every day. Yet people are scared of bags in the dashboard or steering wheel going off...
12-06-14, 09:10 AM
#6
Well, I did not expect that kind of full-on analysis, but great. Thanks SA3R!!
Now does anyone know what it might cost to get the airbag replaced(obviously, serviced by a Mazda dealership)? I have a '93 so mine is only equipped with the steering wheel bag (no passenger dash bag).
Now does anyone know what it might cost to get the airbag replaced(obviously, serviced by a Mazda dealership)? I have a '93 so mine is only equipped with the steering wheel bag (no passenger dash bag).
12-06-14, 09:58 AM
#7
If the air bags are still made you will pay a TON for it new from the dealer. Also you can replace the airbag your self very easily.
I dont get why everyone is so afraid of the airbags?! If I were you id take the money you will sink into an airbag and install and but a nice Sparco wheel and hub! JMO
I dont get why everyone is so afraid of the airbags?! If I were you id take the money you will sink into an airbag and install and but a nice Sparco wheel and hub! JMO
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12-06-14, 08:20 PM
#8
^^Well, this wasn't launched as an opinion survey on who prefers to have an airbag versus an aftermarket wheel. I am interested in the shelf life of the vehicle's safety systems and what may be required to replace and/or 'maintain' them. But thanks for your input 04G35S