855 airbag service vs change

The service label on my 855 TDI 1996 tells me to have the SIPS and SRS airbag
systems serviced or exchanged in April 2007. What exactly would "service" mean?
What is reasonable and economical to do?

Viktor

 

The service label on my 855 TDI 1996 tells me to have the SIPS and SRS

Volvo has extended the lifetime of the airbags, so far by 5 years or more,
cant remember exactly.

Greetings Niels

 

This is an administrative problem, IMO. There is no way to test airbags for
deterioration, but many car mfrs wanted to demonstrate due diligence on
recommended maintenance so they recommended "inspection intervals" - perhaps
in the hope there would be more info when the time came. Now the time has
come. I don't believe there are enough air bag failures to identify a
reasonable life expectancy. Finally, replacement of air bags is unreasonably
expensive for any car old enough that it is an issue.

About all you can do is ensure any SRS warnings are taken care of if they
pop up and enjoy your car.

Mike

 

Are there even any documented airbag failures? I know I saw a clip one
point where they tested a very early airbag in a 20+ year old car and it
still deployed as designed.

 

I'll second this. Prolonged for five years, AFAIK.


Regards, Torsten

 

Interesting. One of the reasons why I switched from the 745 to the 855 were the
airbags. I did not want to give the retirement insurance the chance to collect
my money without having to pay anything . Do the airbags work with dry
explosives ignited by electricity? Or are there pressurized gases which are
released? If there are any electric contact problems, e.g. at the steering wheel
air bag, I expect the SRS warning system to report that?

Regards

Viktor

 

An airbag actuator is a sealed propellant charge, not an explosive. They
are ignited electrically and burn very fast to create gasses which inflate
the bag. The gasses are vented almost immediately, still hot enough to
cause serious burns (as a co-workers' spouse found out the hard way).

Yes, it'll be checking continuity and will generate a fault if it's
not within a certain range.


Gary

 

They use a chemical charge which is usually sodium azide and an
oxidizer, it's an explosive in the same way as black gunpowder in that
if you put it in a sealed enclosure it will explode but it's really just
burning very rapidly. In the case of an airbag, the expanding gasses
fill the bag. It's ignited electrically.

Those things are scary to me, even just on this group there have been a
couple reports of accidental airbag deployments when water got in the
control box and plenty of people are injured when the bag deploys while
their arms are in the way. You also have to be very careful working on
airbag equipped cars and always disconnect the battery before messing
around. In theory the SRS warning will detect faults, in practice
there's so many ways for a circuit to malfunction that you can never
predict them all. Personally I always wear my seatbelt, make sure it's
properly adjusted, pay attention, and drive defensively. I won't buy an
airbag equipped car, and if I did, I'd certainly disconnect or remove it.

 

I have looked the stuff up myself now. The oxidizer is potassium nitrate, the
resulting compounds are nitrogen gas, which fills the bag after ignition within
20-40 msec, and potassium and sodium oxide. Newer air bags work with an
additional compressed gas container.

Still an arm injury is usually less life threatening than the injuries which the
airbags can prevent. The energy is dissipated over a bigger area and time. When
wearing only seat belts, the pressure of the belt over a smaller area and the
head banging around can cause nasty injuries to the big vessels behind the
clavicle and in the neck.

Not turning off brain.exe is always important, I proceed as you except with the
air bags now. Of course the seatbelt has always to be used and the airbag does
not replace it, it is an additional protection. Statistics state that the
airbags reduce letality of car accidents over the protection given by seat belts
alone, so I believe in it. Even a seat belt can be lethal in an accident, but
these cases are very rare, in most instances it protects, so I do also use it
even knowing that there is a little chance that it kills me. Hopefully I will
need neither of them.

Regards

Viktor
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