Fixed Heat Detector with Base
The Fireboy-Xintex Heat Detector uses a single thermistor to sense the air temperature around the detector. This heat detector was designed to detect how fast the temperature is increasing.
Features:
163°F Fixed Heat Detector
Housing: White flame-retardant polycarbonate
Terminals: Nickel-plated stainless steel
Ideal in environments that are dirty or smoky
Unaffected by wind or atmospheric pressure
Remote test feature
Specifications:
Detection Principle: Measurement of heat using a thermistor
Sampling Frequency: Once every four seconds
Supply Voltage: 8.5 V dc to 33 V dc
Supply Wiring: Two wire supply, polarity sensitive
Power-up Time: < 20 seconds
Minimum: ‘detector active’ voltage: 6 V
Holding Voltage: 5 V - 33 V
Minimum Holding Current: 8 mA 
Minimum Voltage to Light Alarm LED: 5 V 
Alarm Reset Voltage: < 1 V 
Alarm Reset Time: One second 
Alarm Indicator: Integral indicator with 360º visibility
Operating & Storage Temperature: -40ºC to +70ºC
Operation:
Open-web casing that enables air to flow freely across a thermistor which measures the air temperature every two seconds 
A microprocessor stores the temperatures and compares them with pre-set values to determine whether a fixed upper limit - the alarm level - has been reached
Detectors the microprocessor uses algorithms to determine how fast the temperature is increasing