What type of fire detection system uses thermocouples?

The correct answer is the system that measures heat from reference because thermocouples operate on the principle of measuring temperature differences through the voltage generated at the junction of two different metals. In a fire detection context, thermocouples can provide an accurate measurement of temperature increases, which are indicative of a fire. They are often used in situations where precise temperature monitoring is necessary, such as in aircraft engines, where detecting abnormal heat levels can indicate an impending fire.

This type of fire detection system is advantageous because it can provide early warnings based on specific temperature thresholds that, when exceeded, may trigger alarms or other safety protocols. By measuring temperature against a preset reference point, the system can reliably identify dangerous conditions.

The other options involve different mechanisms of fire detection that do not utilize thermocouples. Systems based on ionization detect particles produced by combustion, smoke detection systems react to the presence of smoke particles, and visual inspection systems rely on human observation, none of which include temperature measurement through thermocouples.