Fire detection: The use of smoke detectors

Fire is easily one of the most serious causes of damage to lives and property in any part of the world. In Nigeria, there are many cases of fire incidents that have been reported in the past leading to loss of lives and heavy damage to facilities.

Often times, you find preventive measures are rarely in place or very little is done until a catastrophic situation occurs. The result of this is that many fire incidents could have been avoided if basic preventive steps were taken to deal with fire-related matters.

While fire preventive measures are extremely important, this aspect of facility management is often neglected. There are many preventive measures that can be utilized but one that should not be avoided is the installation of smoke detectors in a built environment. In the past, it was almost impossible to find smoke detectors in buildings particularly residential buildings.

However, this trend is changing now due to more awareness and understanding of the concept of preventive action. In circumstances where fire fighters are not readily available or other factors can cause delay in getting them to deal with fire incidents, the least that can be done is to ensure the installation of smoke detectors that are in good working conditions and are regularly tested as part of maintenance activities for optimal performance.

Smoke detectors are the most common form of automatic fire detection and there are different types in the market. The most common are the ionization detector and the photo-electric detector. Others include spot- type smoke detector, aspiration-type smoke detector and projected beam smoke detector.

The ionization smoke detector uses a small amount of radioactive material to ionize the air in the detector’s sensing chambers. When smoke particles enter the sensing chamber, they attach themselves to the ions, thereby causing a change in the electrical current level. This level of current change depends on the concentration of smoke. When the alarm threshold of the detector is reached, the detector signals the fire alarm control panel and an alarm is triggered.

The photoelectric smoke detector has several variations to it. The smoke obscuration type detector detects light from a source that is projected to a photosensitive receiver. As the density of smoke increases, the amount of light from the source that is received decreases prompting an alarm condition to occur when a predetermined alarm threshold is reached.

Aspiration-type smoke detectors use piping networks, and air sampling detector units incorporating advanced technologies, to detect smoke at much lower concentrations than standard smoke detectors. These very early detection systems are used in a variety of applications such as data centers and high rack storage areas. They often work in conjunction with specialized fire suppression systems.

Projected beam smoke detectors are used to provide smoke detection in spaces where the use of spot-type detectors is difficult because of unusually high ceilings or where there’s unconventional architectural features making the use of ceiling or wall mounted devices is impractical or aesthetically undesirable.     

Fire detection and alarm systems provide early warning to building occupants, facilities managers and emergency personnel. Increasingly, these systems incorporate advanced technologies which provide greater reliability and increased capabilities necessary for the complex operational sequences required by modern building design.

Tunde Obileye