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Vehicle safety

Car airbags – operation, safety and regulations

07 February 2023

Modern cars are equipped with a number of systems and solutions to enhance safety in the event of a collision. One of them are airbags – used in various models of cars since the 1970s. How does the airbag system work and what affects its efficiency? 

History of an airbag 

Although an airbag did not become part of the basic equipment of cars until around the 1980s, work on such systems began much earlier. Initially, such solutions were intended primarily for use in aircraft – a patent for this invention was granted as early as 1920. Interestingly, two dentists are responsible for the development of the first airbags. However, with the development of automobiles and the advent of increasingly powerful power units, there was a need for additional protection for drivers and passengers, resulting in the development of airbags for use in cars in the early 1950s. 

The first automotive airbags were based on a mechanical design. A collision or the pressing of an appropriate button by the driver triggered the activation of a spring, whose task was to unlock the supply of compressed air. Such a mechanism, however, was characterized by being too slow, which led to the development of new solutions using electronics or chemical reactions. Since the 1970s, airbags began to be increasingly used in vehicles, now becoming one of the basic components of a car. 

How do airbags work? 

How does the airbag system work? In most modern vehicles, its functioning is based on a combination of the use of an electronic control system (ACU – Airbag Control Unit) and a gas generator. Contrary to its name, airbags are not actually filled with air – instead, chemical compounds such as sodium azide (NaN3) are used to provide a very rapid increase in pressure. The gas is "fired" at speeds as high as approx. 300 km/h. Sodium azide itself is a poisonous substance, but it is quickly broken down into sodium and nitrogen. Due to its toxicity, however, research is underway into the use of other substances, including chemical compounds involving strontium. 

The ACU's task is to determine the appropriate moment of activation according to data collected by a series of sensors that monitor, among other things, the performance of the braking system, current acceleration or pressure on various parts of the vehicle's structure. When a strong enough collision occurs, the ACU activates the gas generator. This in turn is activated by electrical conductors wrapped in flammable material. The result is an explosion that fills a polyamide or nylon/cotton bag with gas. 

The entire process takes only a few dozen milliseconds – ensuring that the airbag activates in the shortest possible time is crucial to ensure safety and protect the driver or passengers from a windshield collision. As soon as the airbag is activated, the gas (decomposed into its basic components, namely nitrogen and sodium) is released through special holes so as not to cause additional injuries after the impact. 

See also: EURO NCAP rating score – how does crash test work? 

Do the airbags work without a seatbelt on? 

 Active head restraints, consisting of a simple, but very effective construction, provide additional protection in case of an accident.
Active head restraints, consisting of a simple, but very effective construction, provide additional protection in case of an accident.

Activating the airbag without a seatbelt being fastened can lead to a variety of dangerous injuries in the event of a collision – including, but not limited to, a broken neck. For this reason, in many cars, the airbag system is deactivated when the driver or passenger is not using a seat belt. It is worth noting that this is not a rule: in some models the ACU system is on at any time, while in others it may be activated according to information from the seat occupancy sensor. However, always remember to fasten your seatbelt – it is a key safety mechanism that can save your health and life in the event of an accident. 

See also: The impact of the correct position behind the steering wheel 

Can an airbag "go off" on its own? 

Like other systems used in automobiles, airbags are subject to various failures. In some situations, the failure of this component can result in a lack of activation at the time of an accident or the airbag exploding on its own without a collision. The primary signal that alerts you to potential problems with this component is the airbag light on the dashboard – you should  address this issue as soon as it lights up. 

Does a car have to have airbags? Legal regulations 

The answer to this question depends to some extent on the year of manufacture and the country of origin of the car. In the European Union, airbags have been mandatory since 2009, while in the United States they have been mandatory since 1998. For vehicles imported from other regions or manufactured earlier, it is an optional feature. When buying an older car, it is therefore worth checking the presence and operability of airbags. 

See also: Elements of passive car safety systems 

Knauf Automotive – automotive parts to support safety systems 

Safety is a key issue when driving a car. To ensure adequate protection for the driver and passengers, not only airbag systems should be applied, but also other solutions related to the car's structure. Knauf Automotive offers lightweight and durable plastic components, made e.g. from EPP (expanded polypropylene), that effectively support the operation of other safety systems – including airbags. 

Do not hesitate to contact us for more information! 

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