Types of Heat Detectors
– Fixed temperature heat detectors
– Most common type of heat detector
– Operate when eutectic alloy reaches eutectic point
– Thermal lag delays heat accumulation at sensitive element
– Operating temperature reached after surrounding air temperature exceeds threshold
– Common fixed temperature point is 58°C (136.4°F)
– Rate-of-rise heat detectors
– Operate on rapid rise in element temperature
– Increase of 6.7° to 8.3°C (12° to 15°F) per minute
– Two heat-sensitive thermocouples or thermistors
– One monitors heat transferred by convection or radiation
– Other responds to ambient temperature
Uses of Heat Detectors
– Heat detectors not designed as life safety devices
– Smoke detectors more suitable for bedrooms and hallways
– Heat detectors useful in areas like kitchen, utility rooms, garage, or attic
– Heat detectors not affected by non-fire related activities or particles
– Mechanical heat detectors can be installed in any area of a home
Factors for Heat Detector Selection
– Each type of heat detector has its own advantages and limitations
– Selection should be based on specific requirements of the area being monitored
– Fixed Threshold Detector less sensitive to rapid temperature fluctuations
– Rate-of-Rise Detector more sensitive to sudden temperature changes
– Choice depends on the nature of the area being protected
References
– The Official State of Nevada Website (9 October 2023). FIRE PROTECTION SYSTEMS (PDF).
– Aspirating smoke detector (in German). 9 October 2023.Sources: https://en.wikipedia.org/wiki/Heat_detector
