Working principle of Airbags in Cars

The airbag system is one of the most important parts of your vehicle safety device. Like seat belts, airbag - a soft pillow to land against in a crash - has been around for many years. In 1980's, first commercial airbags appeared in the automobiles. It's a system consisting of a flexible fabric envelope designed to inflate rapidly during an automobile collision.

Modern vehicle contain multiple airbags in the various sides and frontal locations of the passenger seating position. The most important parts of the success of the airbag system are the Crash Sensors. These small pieces of electronics are designed to tell when the vehicle has been damaged in an accident.

The signals obtained from various sensors are fed into the Airbag control unit (ACU), which determines from the angle of impact the severity or the force of crash along with other variables. 

Airbag system contains a mixture of Sodium Azide (NaN₃), KNO₃ and SiO₂. The reactions, in order, are as follows.

(1)  2 NaN₃ → 2 Na + 3 N₂ (g)

(2)  10 Na + 2 KNO₃ → K₂O + 5 Na₂O + N₂ (g)

(3)  K₂O + Na₂O + 2 SiO₂ → K₂O₃Si + Na₂O₃Si (silicate glass)

• How fast does an Airbag deploy?

An airbag can deploy in about 55 milliseconds, according to the engineering study. This is about the same amount of time it takes you to blink your eyes or sneeze means airbag deployment is very quick.

• How much does an Airbag cost?

If you want to replace or repair an airbag in your vehicle, the cost will vary depending on the type of car, as well as which airbag needs to be replaced. Generally, budget between $400-800 for a driver's side airbag. A passenger side airbag can cost up to $1,000.

• How to know if my car has faulty Airbags?

If your vehicle has an airbag light, and it is lit up, this could indicate faulty airbags or a problem with the airbag system otherwise there is no real way of knowing if the vehicle has a faulty airbag. If the airbag light comes on, it is best to have the vehicle checked out by a professional.