Article by Bill Graefe – Contract Sales Manager
We have all seen it while watching some of our favorite action movies. Our hero is trapped in a building with no escape from their nemeses. But wait, there is a fire alarm pull station within reach! They pull the fire alarm and immediately, all of the sprinklers are activated and a deluge of water is deployed allowing our hero to escape the clutches of the bad guys/gals!
In another scenario, a famous cartoon underwater sea “sponge” is being desiccated under a heat lamp before becoming part of a collector’s display. But as luck would have it, an electrical surge occurs and the smoke from this surge, travels to the fire sprinkler located overhead. The smoke activates the fusible link and water showers down onto the “sponge”; rehydrating him and saving the day!
In our first scenario, all of the sprinklers are activated by simply pulling the fire alarm. This is a common misconception. When one pulls a fire alarm, this simply activates a warning siren to notify people in the building to evacuate. Pulling the fire alarm does not cause the sprinkler system to activate. In addition to this, movies often portray the activation of a single sprinkler triggering the activation of all of the sprinklers in the building; another fallacy. Only sprinklers in the area that are exposed to the rising heat from the fire will activate!
In the second scenario, the movie shows a fire sprinkler activating from the smoke caused by the electrical mishap. Simply put, this is not how sprinklers work! Sprinklers activate once their heat-sensitive frangible bulb or fusible element reach its thermal temperature rating. Once this temperature is reached, the glycerin-based liquid in the frangible bulb expands causing the glass to break which then allows water to flow (wet systems). With the fusible element, solder with a predetermined melting point is utilized along with two metal plates. Similar to the frangible bulb, once the solder reaches the activation temperature, the solder melts causing two spring arms to separate the metal plates which then allows water to discharge from the sprinkler.
Sure, these scenarios make for “good” television and film but do not be fooled, unfortunately, they are a misrepresentation of how fire sprinklers actually do work!