Conventional methods of detecting fire don’t always work, or if they do, they don’t work quickly enough. Depending on the physical characteristics of the room or the materials being protected, you may need a different solution than the traditional fire detector that waits until smoke reaches a certain level on the ceiling where the traditional smoke detector is installed.
When traditional fire alarms aren’t enough
It is true that smoke rises, and traditional smoke detection takes advantage of the fact that no matter where the fire starts, its smoke will end up rising to the upper levels of the room. Some rooms are built in such a way as to make that impractical. The ceiling may be so high that the smoke disperses on the way up. By the time there is thick enough smoke to activate the alarm the fire has grown significant;y, and likely damaged critical equipment and maybe even injured or killed personnel.
Another factor that could influence the effectiveness of smoke detectors is the volume of air flow in a room. Large amounts of air flow, such as you would see in a data center, could make it necessary to supplement regular equipment with multiple fire detectors in order to trigger the necessary warning. This would result in greater costs while not necessarily solving the problem, leaving your equipment and property vulnerable to the risk of fire.
Air sampling units / air sampling smoke detectors (ASSD)
Air sampling units work in places where other kinds of fire detectors typically fail and are one of only five methods specifically approved by the National Fire Alarm and Signaling Code. They can be used in vulnerable areas which contain servers, and inside very cold areas, like refrigerated warehouses. They are able to work well in facilities which have high ceilings or in rooms with MRIs.
The air sampling unit has three main parts: the air sampling pipe, the detector (including the fan and detection chamber), and sampling ports. Air is drawn into the chamber by the fan, which is then measured and checked for hazards. This method is not only accurate but offers pre-warnings not available to other methods.
Also unique to the air sampling unit is its ability to distinguish between different kinds of particles, which means there is less likelihood of a false positive. The ASSD will filter dust out of the room, and ignore common dust particles.
Optical smoke sensors / photo-electric smoke sensors
Optical smoke sensors can be placed in areas around a building to make them less susceptible to false positives, in case there’s a legitimate source of flame. An optical smoke sensor uses the light scatter principle, which analyzes how light is scattered and measured, to correctly identify hazards.
Smoke enters the optical chamber of the optical chamber, where there is a light emitting diode (LED) emitting a signal every 10 seconds. The smoke particles cause the light to scatter, which causes them to be picked up by a photodiode light receptor, triggering an alarm to notify that there is danger.
Optical fire sensors / optical flame detection
The larger the area to be protected, the less reliable traditional smoke detectors will be. In these cases, optical fire sensors may be both the fastest and most reliable solution. The optical fire sensor works by identifying the radiation produced by flames, which is produced in either visible ultraviolet (UV) or infrared (IR) wavelengths.
One drawback to using the optical flame sensor is that is that they sometimes have a harder time distinguishing between real hazards and false positives.