How Do Sprinklers Work?
Did you know that sprinklers are activated by heat or (in rare cases) triggered remotely? However, the most common sprinkler head is heat-only activated, by which a small heat sensitive link fuses or glass bulb breaks at a specified critical pre-determined temperature (called link temperature) allowing the water to flow. Often, the water flow is diverted with a deflector mounted directly in front of the orifice. Much research has been commissioned to optimize the sprinkler design for minimum water flow, diverter effectiveness, droplet size and drop momentum to enable specific kinds of sprinkler applications.
There is a misconception that when a fire starts, it will set off all the sprinklers in the room. This is not the case, except with rare application of a deluge system. Every heat-activated sprinkler has an associated link temperature. When a fire occurs, the heat from the fire rises to the ceiling and heats the sprinklers' links or glass bulbs. When the link in the sprinkler head heats up and reaches this critical link temperature, the sprinkler head opens (by link fusing or bulb breaking.) The first sprinkler head to open is typically the one closest to the fire. Then, (if under ideal conditions such as a flat ceiling, etc.) the sprinklers will open in a radial pattern from the source (fire) outward, as the heat at the ceiling opens up additional sprinklers.