SRS Airbags

Secondary Restraint Safety Device

Airbags are the second important safety mechanism that provides safety to the occupants of a car when the vehicle collides with any object or other vehicle. During a crash the seat belt keeps the occupant in position and airbag gets deployed rapidly by inflating and provides a cushion between the passenger and hard objects like steering wheel or dashboard which protects them from an injury. Since, seatbelts are primary safety device and airbags are the secondary safety mechanism as its name suggest SRS airbags which means Secondary Restraint System. It is important to remember that airbags are effective only when used in tandem with seat belt. An air bag can actually cause serious injury if used improperly and without the seat belt.

Functioning of Airbags in a Vehicle

The Air Bag typically consists of the following three components:

  • The bag itself is made of a thin, nylon fabric, which is folded into the steering wheel or dashboard or, more recently, the seat or the doors.
  • The sensor is the device that transmits a signal and triggers the bag to inflate. Inflation happens when there is a collision which exerts a force approximately at speed of 16 to 24 km per hour. Sensors detects the crash using a mechanical switch that closes with a mass shift and an electrical contact is made. Electronic sensors use a tiny accelerometer that are being etched on a silicon chip.
  • The air bag's inflation system uses the rapid pulse of hot nitrogen gas formed from the chemical reaction of Sodium Azide (NAN3) and Potassium Nitrate (KNO3) to inflate the bag.

The air bag system ignites a solid propellant, which burns rapidly to create a large volume of gas to inflate the bag which is faster than blink of an eye. Within a seconds, the gas quickly dissipates through tiny holes of the airbag, thus deflating the person can move and alights from the car.

Safety Concerns Pertaining to Airbags

It is important to note that the force of an air bag can hurt those who are too close to it. Researchers have determined that the risk zone for driver airbags is the first 2 to 3 inches of inflation. So, placing oneself at minimum 10 inches away from the airbag gives a clear margin of safety. If one sits less than 10 inches away, one can adjust the driving position in the following ways to ensure safety:

  • Move your seat to the rear as far as possible while still reaching the pedals comfortably.
  • Slightly recline the back of your seat.
  • Point the airbag toward your chest, instead of your head and neck, by tilting your steering wheel down (if your steering wheel is adjustable).

The rules are different for children. An airbag can seriously injure or even kill an unbuckled child who is sitting close it or is thrown toward the dashboard during emergency braking. Experts say that the following safety points are important while travelling with kids in a car:

  • Children of age 14 or below should ride buckled up in a properly installed child restraint seat.
  • Infants in rear-facing child seats (under one year old and weighing less 9 kg) should never ride in the front seat of a car that has a passenger side airbag.
  • If a child over one year old must ride in the front seat with a passenger side airbag, he or she should be seated in a front-facing child restraint seat or a properly fitting lap/shoulder belt.