Most conventional sprinkler heads use a small, liquid-filled bulb that acts as a plug to prevent water from escaping out of the sprinkler.Extreme heat causes this liquid to expand, eventually causing the bulbto burst and release 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