Photoelectric fire sensors

Photoelectric fire sensors that detect changes in infrared energy radiated by smoke or by the smoke particles obscuring the photoelectric beam. A relay closes to complete the alarm circuit when smoke interferes with the intensity of the photoelectric beam. 

Multi-sensor detector Is a combination of photoelectric and thermal detectors. The photoelectric sensor serves to detect smoldering fires, while the thermal detector senses the heat given off from fast-burning/flaming fires. 

Once the fire starts to smolder and smoke is present, photoelectric sensors can be used to activate alarms. As the smoke density rises, less light passes from the source to the receiver, and an alarm is activated. 

Instruments or articles with low activities (e.g., clocks, sun lamps, photoelectric cells, fire alarm sensors, radioactivity counters, x-ray tubes). 

Smoke Detectors In many fires there is smoke before there is any significant heat buildup. As a result, smoke detectors will usually detect fire before heat sensors. Smoke detectors operate on one of two principles ionization or photoelectricity. 

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