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+--- Thread: NFPA 704 - Those Mysterious Color Code Diamonds on Buildings for Firefighters (/thread-4705.html)
NFPA 704 - Those Mysterious Color Code Diamonds on Buildings for Firefighters - Yazata - Dec 28, 2017
They indicate to firefighters what kind of hazards exist inside a building (usually an industrial space).
Here's how to decode them.
The red on top indicates flammability. The blue on the left indicates environmental hazards like poisonous chemicals. The yellow on the right is chemical reactivity. And the white at the bottom indicates any other dangers with letter codes.
Each one can contain numbers from 0 to 4, indicating ascending levels of danger.
For flammability, 0 is no danger, 1 means contents must be heated very hot before anything catches on fire, 2 means modest heating can make contents burn (paper etc.), 3. means flammable liquids like gasoline and 4 means flammable gases like propane.
For blue, it ranges from 0 (no special danger) to 4 (brief contact can be fatal like hydrogen cyanide or phosgene).
For yellow, it ranges from 0 (stable in fire and doesn't react with water) to 4 (highly explosive).
More here:
https://en.wikipedia.org/wiki/NFPA_704