| SERIES 65 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 SIMLAR 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 WHICH CAUSES THE DETECTOR TO CHANGE TO THE ALARM STATE. |
