Hello
i just want to ask you that whether the Piezo electric disc "knock sensor" can detect accident in the car.
because i know that it can detect sound and vibration...
what i need is to detect the pressure, is it suitable for detecting high level of impacts ??
thanks 
No, sorry it would not work, an accelerometer would be a suitable solution. You could also use it for data logging etc
Duane B
Thanks..
But i need to use another sensors (pressure or vibration) with accelerometer, what you suggest ?
Ahmad
Accelerometer should be fine, why do you need to use other sensors ?
Duane B
so if i use only accelerometer, is it alone suitable for detecting high level of impacts?
for example if i use it in the car for detecting accident
ahmad91:
so if i use only accelerometer, is it alone suitable for detecting high level of impacts?
An accelerometer, by definition, measures acceleration or the rate of change in velocity. In an automobile crash there is usually significant changes in the respective velocities of the vehicles involved. Therefore it shouldn't be a surprise that accelerometers are the primary type of sensor used in automobile crash tests by both government and independent vehicle safety organizations.
A knock sensor would be more appropriate for an anti-theft system or to detect only fender-benders or other low speed accidents.