A THERMISTOR IS A TEMPERATURE SENSITIVE RESISTOR THAT IS A KEY PART OF THE SENSING ELEMENT WITHIN A DETECTOR. MOST HEAT DETECTORS USE THERMISTORS TO SENSE HEAT. ONE THERMISTOR IS EXPOSED TO THE AMBIENT TEMPERATURE AND THE OTHER IS SEALED.

CLASSIFICATION IS DETERMINED ACCORDING TO GIRS 1 AND 6 OF THE COMBINED NOMENCLATURE. CN 85334090 FOR OTHER VARIABLE RESISTORS, INCLUDING RHEOSTATS AND POTENTIOMETERS