Heat
Detector
The heat detector operates by using a matched pair of
thermistors to sense heat. One thermistor is exposed
to the ambient temperature, the other is sealed. In
normal conditions, the two thermistors register similar
temperatures, but, on the development of a fire, the
temperature recorded by the exposed thermistor will
increase rapidly, resulting in an imbalance of the thermistors
and causing the detector to change to the alarm state.
Rate
of Rise detectors are designed to detect a fire
as the temperature increases, but they also have a fixed
upper limit at which the detector will go into alarm
if the rate of temperature increase has been too slow
to trigger the detector earlier.
Fixed
heat detectors only change to the alarm state at
a preset temperature.
|