Heat detectors are the oldest and least expensive type of automatic fire detection. They are designed to operate when there is a specified or predetermined rate of temperature change or when a detecting element reaches a predetermined fixed temperature. The two types of heat detectors are spot and line type.
A spot type heat detector monitors temperature at a given point. These detectors vary with respect to the mechanisms used to detect heat. The two most common types of spot type heat detectors are:
Fixed-Temperature Heat Detectors - designed to initiate an alarm when its heat sensitive material or element is heated to a specific temperature. The air temperature at the time of alarm is considerably higher as it takes time for the surrounding air to raise the temperature of the element to its set point. The operating range of these detectors start at 100F. There are two types of fixed-temperature heat detectors:
- Restorable - returns to its ready state without any interaction from an outside source, once it has cooled below its set point.
- Non-Restorable - requires replacement of its element after actuation.
- Rate-of-Rise Heat Detectors - operate on a rate-of-temperature change per unit of time basis. This type of heat detector contains a chamber with a calibrated vent. When the air in the chamber expands faster than it can escape from the vent, the increase in pressure causes the electrical contacts to close sending a signal to the fire alarm control unit. If the air in the chamber rises slowly and can escape from the vent, the electrical contacts do not close and there is no alarm.
Other types of spot detectors are:
- Rate-compensated heat detector
- Combination heat detector
- Pneumatic heat detector
Line type heat detectors are used in applications where it is not practical to use spot type detectors, such as on long industrial conveyors or cable trays. These detectors use heat-sensitive materials which affect the current flow through the electrical conductors.
BFPE International can assist you with making the right choice of heat detection device for your application. Our product offering includes NOTIFIER , Fire-Lite , SIEMENS , Silent Knight , System Sensor , as well as other major fire alarm systems available in today’s market. We appreciate the opportunity to design, install, service, and test and inspect your system. Please contact us for more information.