An airbags intended purpose is to slow the passengers forward momentum as fastly,quickly and as safely as possible in about one twenty fifth of a second. the air bag inflates to about 22.5 liters. There are three parts of an air bag that allow it to do this. The crash sensor, the inflator, and the actual airbag make up the common car airbag.
The bag itself is made of thin nylon fabric that is put into the steering wheel or dashboard.
The sensor is the device that tells the bag to inflate. Inflation happens when there is a collision force equal to running into a brick wall at 10 MPH. A switch is flipped telling the sensors that a crash has occurred. The sensors receive information from an accelerometer built into a microchip. Due to the mechanical and electrical processes involved this area of an air bag is most likely to fail.
The airbag's inflation system combines sodium azide (NaN3) with potassium nitrate (KNO3) to produce nitrogen gas. Hot blasts of the nitrogen inflate the airbag