Since the invention of the first automatic fire alarm system in the late 19th century, innovators have continued to advance fire safety technology in an effort to protect life and property. Costs have declined while reliability has improved, giving firefighters more notice and building occupants more evacuation time. While fire prevention is ideal, it will never be possible to prevent all occurrences, and fire safety equipment is a vital component of all buildings.
Fire Alarm Systems
Most public buildings are required to have some sort of fire alarm system, according to installation guidelines from the National Fire Protection Association (NFPA) and the National Fire Alarm Code. There are two basic types of fire alarm systems in use today: manual and automatic.
Most manually activated alarms are easily accessible, hand-operated alarms that allow anyone in a building to signal the presence of fire. Often, these manual alarms are coupled with automatic systems that continually monitor the environment for signs of a fire and suppress a fire outbreak with sprinkler systems or fire extinguishers. As part of a comprehensive system for fire safety, some designs include fire alarm lights, which can direct building occupants during power outages and under smoky conditions that limit visibility.
Smoke alarms use physical or optical detection systems to sense smoke and alert building occupants when it is found. Most people are familiar with the ionization physical detection method, which samples the nearby air for smoke particles. These detectors have been commercially available since the 1960s; since they have become more affordable, these fire alarms have worked their way into most modern buildings. Since many smaller units require batteries, some maintenance is required; the device only works if properly maintained. Unfortunately, some estimates place the number of poorly maintained and nonfunctional smoke alarms at 30 percent of all installed units.
Optical detectors, which are less common, use light beams to detect smoke particles. The presence of smoke in the air changes the quality of the light in the room, and optical detectors can sense this. They are often used in large rooms, and this type of detector is less sensitive to false alarms. However, they also tend to be slower detecting very hot fires than physical ionization systems are.