What gas is used in car airbags?
2 Answers
Car airbags use nitrogen gas. Here is the relevant introduction: Composition of the airbag system: The airbag system mainly consists of sensors, a microprocessor, a gas generator, and the airbag itself. Principle of the airbag system: Sensors and the microprocessor are used to determine the severity of a collision and transmit signals. The gas generator, upon receiving the signal, initiates an ignition action, igniting solid fuel to produce gas that inflates the airbag, causing it to rapidly expand. When a collision occurs while the car is in motion, the airbag sensor first receives the impact signal. If the impact reaches a predetermined intensity, the sensor activates and sends a signal to the electronic controller. Upon receiving the signal, the electronic controller compares it with stored data. If the conditions for airbag deployment are met, the drive circuit sends an activation signal to the gas generator in the airbag module. The gas generator, upon receiving the signal, ignites the gas-generating agent, producing a large volume of gas. This gas is filtered and cooled before entering the airbag, allowing the airbag to break through the padding and deploy rapidly within an extremely short time. This forms an elastic cushion in front of the driver or passenger, which then deflates and contracts in time to absorb the impact energy, effectively protecting the head and chest from injury or reducing the severity of injuries.
When I first started driving, I was also curious about the gas in airbags. Later, a friend who's a car mechanic told me the gas is mainly nitrogen. It's not pre-filled; instead, there's something like rocket propellant in the airbag module called sodium azide or other solid chemicals. When you crash, sensors trigger a thermal reaction, causing those materials to rapidly burn or decompose, generating a large amount of nitrogen gas to inflate the airbag. This nitrogen is inert, meaning it's neither flammable nor toxic, protecting passengers from injury when they hit the front. The whole process completes in fractions of a second—speed is crucial, otherwise the airbag would deploy too late. After deployment, the gas slowly leaks out, leaving behind some white powder as residue, but there's no need to worry about it being harmful to health. I think it's important to regularly check the airbag system warning light—don't ignore those alerts, safety comes first.
