The why and how of airbags
The why and how of airbags
When people look at buying a new car, they frequently investigate if a car has airbags, and if so, how many. But once people have bought their car, they generally forget about airbags until they need them – in a hurry! Far fewer people do any research towards how airbags work and when they work. Here are a few facts to keep you educated.
Firstly, airbags are deployed by a pyrotechnic device (a detonator) that causes a small, controlled explosion that ignites gases causing them to expand incredibly rapidly. From the time of an accident to when the airbag is fully deployed and inflated is typically between 15 and 60 milliseconds (which is 15 thousandths to 60 thousandths of a second)! As it inflates it unfolds and pops out of its housing, creating a gas-filled cushion that prevents your head or other body part from hitting anything hard. The cushion slows you down more gradually than an impact with something hard would.
The correct technical name for an airbag is a supplementary restraint system (SRS) or supplementary inflatable restraint (SIR), and the term 'supplementary' is key here: they are designed to be used alongside the humble seat belt. If you don't use your seatbelt an airbag either won't deploy, will be ineffective, or would even harm you.
The most common airbags are front airbags, usually for both the driver and the front passenger. They are housed in the steering wheel and dashboard, which open in the event of an accident to allow the airbags to deploy. A knee airbag is also common, and it guards the lower legs from hard objects. So if a car's specs say it has two airbags, they will be front airbags for the driver and front passenger.
There are also side airbags, usually housed in the front seats, which prevent or reduce harm from side impacts, aimed at the front occupants.
Curtain airbags deploy from the roof of a car above the doors, frequently the length of the passenger cabin, and help to protect all occupants from side impacts.
Airbags are designed to deploy under certain conditions, not in every accident. They make use of a accelerometer that detects when a vehicle reduces speed very quickly, more quickly than braking can achieve. When this happens, the gases are ignited and the airbags deployed.
Some airbags only operate when the seatbelts are being used. Others detect when there is someone sitting on the passenger seat and only deploy then.
There have been reports of people being injured by the airbags themselves, but this is normally a minor injury such as burning from the ignited gases or a superficial injury from the airbag. That said, airbags are not a sure thing and statistics suggest that they reduce fatalities of front occupants by approximately 30%.
Please not that it is recommended that children under the age of 12 are placed in the rear seats in a car seat or booster seat, even if the vehicle is fitted with front airbags. Infants should be placed in appropriate child seats in the back seats. Because airbags are designed to save average-sized males, they can actually be of danger to children.
*Every new Toyota and Lexus vehicle on sale in South Africa is fitted with driver and passenger airbags as standard, while many Toyota and Lexus vehicles feature advanced safety systems with a number of airbags as standard, in addition to a raft of other passive and active safety features.