Detection: Purpose

Detection systems are designed to a) activate an alarm, b) adjust vehicle operation, or c) activate fire suppression. Once a fire is detected, some systems notify the driver by activating an alarm bell and/or a light on the instrument panel. The alarm signal may also alter the function of various systems to enhance fire safety. For example, in some vehicles the same signal that activates the alarm shuts down the cooling and ventilation fans (to reduce spread of fire and prevent dispersal of suppression agents), and may alter engine operation to encourage the driver to get off the road quickly. Early notification may also give the driver an opportunity to intervene with a manually activated fire extinguisher before the fire is beyond the scope of the extinguisher.

The fire detection signal is also used to activate automatic suppression systems. Whether a manual or active system is used, the increased airflow due to vehicle motion decreases the effectiveness of the suppression agent. There is a trade-off in suppression system design; waiting to activate the system until the vehicle slows or comes to a stop prevents the agent from being blown away by the additional airflow, but allows the fire to grow more and possibly exceed the systems ability to suppress it.