You've heard about the importance of a properly maintained smoke detector. You've probably also heard the annoying beeping noise it makes when it needs some attention. Have you also heard that a smoke detector is all you need for fire protection? If so, you've heard another one of the most common myths regarding fire sprinkler systems: We don't need them if we have a smoke detector. Some even believe that smoke detectors can put out fires. They cannot. Smoke detectors are designed to alert us to a potential fire, and in cases where they're hooked up to an alarm system, alert the fire department. They're an important part of a fire prevention system, as are fire sprinklers. The presence of one does not cancel out the need for the other. They work together to save life and property from fire.
When a fire starts, the resulting smoke will eventually set off a smoke detector alerting residents to danger. This process can be quite slow depending on where the smoke detector is located. Meanwhile, the fire is growing. Alerting residents to the presence of fire is important. But, so is putting the fire out. When a fire starts, it quickly heats the air directly above it. This air rises and is pushed out to either side when it hits the ceiling. As this hot air reaches a sprinkler head, that sprinkler head is activated.
Not just any heat source will trigger a sprinkler system to activate. The sprinkler heads must detect a high enough temperature -- usually between 135 and 165 degrees Fahrenheit (57 to 74 Celsius). Most sprinkler heads are equipped with a glass trigger filled with a glycerin-based liquid that expands at the appropriate temperature, breaking the glass and activating the sprinkler head. The sprinkler head is attached to a system of pipes that are hidden behind the walls or ceiling. These pipes wind through the building and outside to connect with a reliable water source. When the sprinkler head is triggered, a valve to the pipe system is opened, releasing the water that is kept under pressure from the pipes. The water is quickly pushed out of the pipes through the sprinkler head, spraying water downward and out to the sides. This carefully designed spray of water extinguishes the fire below and prevents it from spreading.
Fire sprinkler systems have revolutionized fire safety by automatically putting out fires in the room of origin and preventing fires from spreading or re-igniting. The amount of time this process requires depends on the type of fire sprinkler system. We'll learn more about the different types of fire sprinkler systems on the next few pages.