When
should
an air bag inflate?
The air bag
is
designed to inflate
in
moderate to severe
frontal or near-frontal crashes. The air bag
will
inflate
only
if
the impact speed is above the system’s designed
“threshold level.”
If
your vehicle goes straight into a
wall that doesn’t move or deform,
the
threshold level is
about
9 to
15
mph (14 to 24 km/h). The threshold level
can vary, however, with specific vehicle design,
so
that
it can be somewhat above or below this range. If your
vehicle strikes something that will move or deform, such
as a parked car, the threshold level
will
be higher. The
air bag is not designed to inflate in rollovers, side
impacts or rear impacts, because inflation would not
help
the
occupant.
In any particular crash, no one can say whether an
air
bag should have inflated simply because of the damage
to a vehicle or because
of what the repair costs were.
Inflation is determined by the angle
of
the impact and
the
vehicle’s deceleration. Vehicle damage is only one
indication of this.
What makes an air bag inflate?
In
a
frontal or near-frontal impact
of
sufficient severity,
the air bag sensing system detects that the vehicle is
suddenly stopping as a result of a crash. The sensing
system triggers a chemical reaction
of
the
sodium azide
sealed
in
the inflator. The reaction produces nitrogen
gas, which inflates the air bag. The inflator, air bag and
related hardware are all part of the air bag modules
packed inside the steering wheel and in the instrument
panel
in
front of the right front passenger.
How
does an air bag restrain?
In moderate to severe frontal or near-frontal collisions,
even belted occupants can contact the steering wheel or
the instrument panel. The air
bag
supplements the
protection provided by safety belts. Air bags distribute
the force
of
the impact more evenly over the occupant’s
upper body, stopping the occupant more gradually. But
air bags would not help you
in
many types
of
collisions,
including rollovers, rear impacts and side impacts,
primarily because an occupant’s motion
is
not toward
the
air bag. Air bags should never be regarded
as
anything more than
a
supplement to safety belts, and
then only
in
moderate to severe frontal or near-frontal
collisions.
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