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Cars in motion have a momentum of their own and the riders traveling in the car move along with the car at its speed until it crashes and comes to a sudden halt. In the event of a car collision, the force needed to stop the passenger is very large as the rider’s momentum remains the same while the car’s momentum has changed to zero.
The purpose of an airbag is to decrease the passenger’s speed to zero with minimum damage. However, the device has to work within several restraints. The air bag gets only a fraction of a second and the gap between the rider and the dash board or steering wheel to perform its job. However, even this can prove to be of the highest value if the rider is brought to a halt slowly and uniformly.
The components of an air bag are:
The bag itself is made of a fine nylon material and is creased into the dashboard or steering wheel, and of late, the seat or door.
The second part is the sensor, the mechanism which informs the bag to inflate. The bag gets inflated when a crash force equivalent to running into a brick wall at 10 to 15 miles per hour is applied.
The inflation system present within the airbag contains sodium azide (NaN3) and potassium nitrate (KNO3) which react to release nitrogen gas. The air bag gets inflated by hot discharges of nitrogen.
The inflation system of an air bag is similar to that of a solid rocket booster. A solid propellant, which is set to fire by the air bag system, undergoes combustion very quickly to produce a huge amount of gas, which in turn inflates the air bag. The bag virtually spurts at a speed of 200 mph, and then immediately, the gas disperses through minute holes in the bag, thus collapsing the bag allowing you to move. Although this entire process occurs in just one-twenty-fifth of a second, the extra time is sufficient to avert any grievous injury.
Air bag manufacturers use talcum powder or cornstarch to store them within the cars to keep the bags flexible and greased.
Safety:
Researchers have found that anyone within a distance of 2 to 3 inches of the air bag is at risk of getting hurt. The ideal distance is 10 inches from the driver’s seat air bag. However, children must be very careful while using airbags as an air bag can be extremely dangerous to a child without a seat belt who is too close or is flung towards the dash board in case of emergency braking.
Deactivation:
The National Highway Traffic Safety Administration (NHTSA) has come up with a rule in 1997 that permits manufacturers of airbags to reduce their power by 20 to 35% especially after reports of faulty or highly powerful airbags injuring kids. Also 1998 onwards, repair shops and dealers could fit on/off switches in cars which had an authorization letter from NHTSA that permitted the air bags to be turned off.
The future of air bags:
Car manufactures have now realized the importance of producing side air bags as 30% of accidents are the result of side crashes. A lot of car air bag tests are being sponsored by NHTSA using data collected by research.
The technology of vehicle safty air bags is still nascent and is growing rapidly. Therefore, a world of possibilities lies ahead for this area as better designs are being developed based on new concepts and actual crash data. So the next time you decide to drive make sure that your car has a safety air bag installed in the vehicle to protect you from any car crash.