Fire sprinkler temperature ratings and color code table

Each closed-head fire sprinkler is held closed by either a heat-sensitive glass bulb or a two-part metal link held together with a fusible alloy.

The glass bulb or link applies pressure to a pipe cap which acts as a plug which prevents water from flowing until the ambient temperature around the sprinkler reaches the design activation temperature of the individual sprinkler. The bulb breaks as a result of the thermal expansion of the liquid inside the bulb. Below the design temperature of fire sprinkler, the bulb does not break, and above the design temperature, it breaks. The time it takes before a bulb breaks is dependent on the temperature.

The liquid in the glass bulb is color coded to its temperature rating, for example, the standard sprinkler head with a blue bulb indicating a high release temperature.

Fire sprinkler temperature ratings and color code table

Temperature classification	Temperature rating		Color code		Max ceiling temperature
Temperature classification	Fahrenheit (°F)	Celsius (°C)	Sprinkler frame	Glass bulb	Max ceiling temperature
Ordinary	135 ~ 170	57 ~ 77	Unpainted or black	Orange-135°F (57°C)	100°F (38°C)
Ordinary	135 ~ 170	57 ~ 77	Unpainted or black	Red-155°F (68°C)	100°F (38°C)
Intermediate	175 ~ 225	79 ~ 107	White	Yellow- 175°F (79°C)	150°F (66°C)
Intermediate	175 ~ 225	79 ~ 107	White	Green- 200°F (93°C)	150°F (66°C)
High	250 ~ 300	121 ~ 149	Blue	Blue- 250°F (121°C)	225°F (107°C)
High	250 ~ 300	121 ~ 149	Blue	Blue- 286°F (141°C)	225°F (107°C)
Extra high	325 ~ 375	163 ~ 191	Red	Purple- 325°F (163°C)	300°F (149°C)
Extra high	325 ~ 375	163 ~ 191	Red	Purple- 360°F (182°C)	300°F (149°C)
Very extra high	400 ~ 475	204 ~ 246	Green	Black	375°F (191°C)
Ultra high	500 ~ 575	260 ~ 302	Orange	Black	475°F (246°C)
Ultra high	650	343	Orange	Black	625°F (329°C)

From Table 6.2.5.1 NFPA 13 2007, it indicates the maximum ceiling temperature, nominal operating temperature of the sprinkler, color of the bulb or link and the temperature classification.

Kindly note: The sensitivity of a fire sprinkler can be negatively affected if the thermal element has been painted; thus, no painting on the fire sprinkler when installation.

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