How do fire sprinkler systems work?

Most sprinkler heads contain a small bulb with a colored liquid inside. This bulb acts as a plug to prevent water from escaping out of the sprinkler. The heat from a fire causes this liquid to quickly expand. Once the pressure in the vial gets too high, the bulb bursts and releases the water behind it.

The liquid inside the bulbs comes in a variety of colors, and each color represents the temperature required to activate the sprinkler:

• Orange – 135°F
• Red – 155°F
• Yellow – 174°F
• Green – 200°F
• Blue – 286°F
• Purple – 360°F
• Black – 440°F

Since the fire sprinklers are activated by heat, there is no risk of accidental activation of your fire sprinkler system by smoke or dust in the air. That said, the bulbs are very fragile and any tampering could cause them to go off. If a sprinkler head gets accidentally knocked off (by a forklift, truck, repairman, etc.), there’s going to be lots and lots of water flowing through that sprinkler head until the system is shut down.