Much of fire sprinklers activity is portrayed and viewed from a Hollywood perspective.
Myth #1: Smoke will trigger a sprinkler system to go off.
Reality: Automatic fire sprinklers work using either a fusible link or frangible bulb. This bulb or link (depending on the sprinkler head installed) activates due to a change in temperature, not by smoke particulate. In a frangible bulb, liquid is kept inside of a glass tube. When the heat reaches a certain temperature (165 degrees Fahrenheit in most office buildings, but it can be more or less depending on the application), the liquid expands causing the glass to shatter. Once the glass shatters a flange is released and the water comes out of the sprinkler head. How these heads operate varies by system, but it’s essentially always the same…. This brings us to Myth #2.
Myth #2: When one sprinkler head goes off, all sprinkler heads go off.
Reality: This really wouldn’t happen unless you have a deluge system. Deluge systems are used only in very specific applications and are not that common. In the majority of sprinkler systems, only one head is activated at a time. As heat spreads, more sprinkler heads are activated. In a deluge system, once one head is activated, they will all go off. Studies have shown that in a majority of fires, fewer than eight sprinkler heads are needed to control the blaze.
Myth #3: Sprinkler systems can be set off using a cigarette lighter.
Reality: Refer to Myth #2, as they’re closely related. While the flame from a cigarette lighter, if held closely enough, could activate a sprinkler head, it would only ever do just that. Activate one sprinkler head. The water would immediately put the small flame out and you’d get a pretty good shower. It wouldn’t flood your building as only one head would go off from this amount of heat (unless, of course, it’s a deluge system).
Myth #4: Sprinkler systems can be set off by pulling a switch or fire alarm.
Reality: As we’ve discussed, automatic sprinkler system heads are activated by heat from a fire. While they are linked to the fire alarm, they cannot be activated by pulling a simple handle (although there are deluge systems that can be activated this way). The system can be entirely shut down by tampering with either the gate valve or butterfly valve (depending on the type of sprinkler system installed).