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DoctorD
DoctorD, Auto Service Technician
Category: Car
Satisfied Customers: 763
Experience:  ASE Master, AAA State 1st place, Rotary Club, 20 years Exp.
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At what speed do airbags deploy?

Generally speaking, over 25 miles per hour (MPH). The impact must be frontal and not side. 
That’s 25 MPH as if you hit a wall, non-moving obstacle. If you hit a car from behind and it moves forward then the impact must be much greater to fire the bags. Also, hitting a car head on when both vehicles are moving at say 12 MPH will set them off. So, any combined frontal force over 25 MPH will usually do it.

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Question

How fast do you have to go for airbags to deploy?

Submitted: 10 years ago.
Category: Car
Expert:  DoctorD replied 10 years ago.

Generally speaking, over 25 miles per hour (MPH). The impact must be frontal and not side.

That’s 25 MPH as if you hit a wall, non-moving obstacle. If you hit a car from behind and it moves forward then the impact must be much greater to fire the bags. Also, hitting a car head on when both vehicles are moving at say 12 mph will set them off. So, any combined frontal force over 25 MPH will usually do it.

Deploying airbags explained

Airbags are made of stretchable material that is stored tightly in different locations throughout a vehicle. Airbags can be found in the dashboard, as well as the sides of the car. When an accident occurs, the airbags fill up with nitrogen gas and offer padding to help prevent so the driver and passenger from being thrown from the vehicle when an accident occurs.

Airbags have a crash sensor. These electronic sensors are made to know when a vehicle has been damaged. The sensors can indicate when different actions occur, such as when extra pressure is put on the car during a collision, and stopping suddenly. Other sensors within the airbag control unit gauge the speed of the wheels, how much pressure is put on the brakes, and if passengers are wearing a seat belt.

When the control unit verifies an accident has occurred, a signal is sent to the inflator system. The inflator initiates a chemical charge, sending nitrogen gas that fills up the airbags. When the airbags fill up, it comes through the vehicles paneling to protect those in the vehicle. This happens instantly, normally within 25 - 50 milliseconds. After the airbag has deployed, it will deflate itself.

Speed of deploying airbags

The speed in which an airbag will deploy depends on the vehicle and the accident. Typically, the airbag will come out at a  speed of 100 - 220 miles per hour. Going this speed, the airbag can cause damage to passengers, so it is recommended to be at least 10 inches from where the airbag is located. Wearing a seatbelt keeps passengers from becoming too close to the airbag.

Faulty airbags

If a vehicle has an airbag light indicator and the light is lit up, this could mean the airbag is faulty, or there is a problem with the system. Airbag and airbag sensors can be difficult and should be fixed by a professional immediately. If the vehicle does not have the airbag lights, typically there is no way to determine if there is an issue with the airbags.