Living With Airbags—Literally!

by Don Elliott on March 14, 2012

AirbagsPassive restraint systems have been standard equipment on cars in the United States since seat belts were first mandated back in the ‘70s. Thousands of lives have been saved because of seat belt usage.

In 1998, the government mandated driver and passenger-side airbags in all cars, and a year later in all light duty trucks. Since then, airbag technology has expanded to include up to eight airbags located throughout the car.

Since they were first installed, airbags have been saving lives and creating controversy. The cost of airbags has been an issue from the beginning. Even though the costs have been coming down, the cost of car safety has added a couple of thousand dollars to the cost of cars.

Costs aside, the job of the airbag is an explosive one—literally! An airbag consists of four parts:

  • Crash Sensor – Sensors are deployed around the car to “read” the impact, generally required to exceed 10-15 miles per hour. More than one sensor must be activated to ignite the airbag.
  • Control Module – The control module is a small computer that analyzes the data from the crash sensor and sends the signal to ignite the airbag.
  • Inflation System – The airbag has to inflate in .03 seconds or less to be fully inflated when the driver or passenger is thrown forward just .05 seconds into a frontal collision event. The inflator is actually a chemical reaction. An electrical pulse from the control module creates a reaction between sodium azide and potassium nitrate to produce an explosion of nitrogen to inflate the airbag.
  • AirbagAirbags are made of a thin nylon fabric engineered to withstand rapid inflation at 200 miles per hour. The fabric is porous to allow the bag to deflate shortly after it inflates. Talcum powder or corn starch is sifted over the bag to keep it pliable for inflation.

In a front-end collision, the car stops very quickly. Passengers and loose items inside the car continue to travel forward at the same speed the car was traveling before the impact. The seat belt and shoulder harness keep the occupants inside the car and connected to the relatively soft seat surface. However, the head and upper body continues to fly forward. Airbags catch the head and face, preventing them from smashing into the steering wheel, dashboard, and windshield as the car collapses around the passenger compartment.

Other airbags within the car operate slightly differently, but their purpose is the same; to slow down the motion of the passenger and prevent tender body parts from crashing into hard car parts. The used car value added by airbags is difficult to measure unless your life was saved when the airbag literally exploded in your face.

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