Airbags - A Supplementary Restraint System

Thursday, 13 February 2014

Airbags have certainly been a great leap forward in crash protection. An airbag is a SRS or secondary /supplementary restraint system. In other words, they are designed to work in conjunction with the seatbelt to help reduce the risk of injury in the event of a crash.

These days a car may have several airbags on board. Apart from the one located in the hub of the steering wheel, there may also be a passenger side airbags as well as side impact air curtains. The level of equipment varies from car to car so again this something you need to check out. I want to stress at this point that I’m a big fan of air bag safety technology.

They are fantastic life saving device, as long as you do two things.

        1.    Always wear the seat belt
        2.    Keep the deployment area of the air bag free from obstruction.

Thanks to the movies and TV, most people have the belief that when an airbag inflates that it does so gradually and remains up. The perception is that it is just a big fluffy pillow. However this is not the case, the airbag is an explosive device.

When the sensors on board the car detect an impact that is severe enough to trigger the airbag to deploy, an explosive charge inflates the bag. The bag itself bursts through a seam and inflates.

In this country the deployment rate is around 220km/h. This means that form the time of impact it only takes about 45 milliseconds for the bag to fully inflate and start then deflating.

The whole process can all be over in around 150 milliseconds. So in less than the time it takes you to blink, the bag has fully inflated and is already starting to deflate. The idea is that the deflation occurs as the upper body arrives and therefore cushioning the impact. This is why the seatbelts are so important. The belts stop the person’s body being thrown forward and colliding with the airbag as it is inflating.

The concern here is that as the person moved forward there would be a huge amount for force from the airbag hitting the body. That would be like throwing yourself against a solid object at 300km So make sure you and your passengers buckle up.   

You’ll notice that there are warnings on visors and in the owner’s manual advising that getting any object between you and the airbag could cause serious injury. From a passengers point of view this means not having objects rest on your lap or resting your feet up on the dash. For a driver it means having a steering technique that avoids the arms crossing over in front of the airbag. 
Airbags are also continuing to improve and the next generation of airbags can take a number of variables into account to control the deployment rate. Airbags will not deploy in a rear end crash. They are designed to work in frontal or semi frontal impacts.

Airbags are fantastic, life saving devices, but just remember the that you need to keep the deployment area free from obstruction and always need to wear your seat belts.

Drive Safely


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