What Is NFPA 704 or the Fire Diamond?

This is an example of a NFPA 704 warning sign. The four colored quadrants of the sign indicate the types of hazards presented by a material. This is the NFPA 704 for sodium borohydride. public domain

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Updated on July 22, 2018

You probably have seen NFPA 704 or the fire diamond on chemical containers. The National Fire Protection Association (NFPA) in the United States uses a standard called NFPA 704 as a chemical hazard label. NFPA 704 sometimes is called a "fire diamond" because the diamond-shaped sign indicates flammability of a substance and also communicates essential information about how emergency response teams should deal with a material if there is a spill, fire or other accident.

Understanding the Fire Diamond

There are four colored sections on the diamond. Each section is labeled with a number from 0-4 to indicate the level of hazard. On this scale, 0 indicates "no hazard" while 4 means "severe hazard". The red section indicates flammability. The blue section indicates a health risk. Yellow indicates reactivity or explosivity. The white is section is used to describe any special hazards.

Hazard Symbols on NFPA 704

Symbol and Number	Meaning	Example
Blue - 0	Does not pose a health hazard. No precautions are necessary.	water
Blue - 1	Exposure may cause irritation and minor residual injury.	acetone
Blue - 2	Intense or continued non-chronic exposure may result in incapacitation or residual injury.	ethyl ether
Blue - 3	Brief exposure may cause serious temporary or moderate residual injury.	chlorine gas
Blue - 4	Very brief exposure may cause death or major residual injury.	sarin, carbon monoxide
Red - 0	Will not burn.	carbon dioxide
Red - 1	Must be heated in order to ignite. Flashpoint exceeds 90°C or 200°F	mineral oil
Red - 2	Moderate heat or relatively high ambient temperature is required for ignition. Flashpoint between 38°C or 100°F and 93°C or 200°F	diesel fuel
Red - 3	Liquids or solids that readily ignite at most ambient temperature conditions. Liquids have a flash point below 23°C (73°F) and the boiling point at or above 38°C (100°F) or flash point between 23°C (73°F) and 38°C (100°F)	gasoline
Red - 4	Rapidly or completely vaporizes at normal temperature and pressure or readily disperses in air and readily burns. Flashpoint below 23°C (73°F)	hydrogen, propane
Yellow - 0	Normally stable even when exposed to fire; not reactive with water.	helium
Yellow - 1	Normally stable, but may become unstable elevated temperature and pressure.	propene
Yellow - 2	Changes violently at elevated temperature and pressure or reacts violently with water or forms explosive mixtures with water.	sodium, phosphorus
Yellow - 3	May detonate or undergo explosive decomposition under the action of a strong initiator or reacts explosively with water or detonates under severe shock.	ammonium nitrate, chlorine trifluoride
Yellow - 4	Readily undergoes explosive decomposition or detonates at normal temperature and pressure.	TNT, nitroglycerine
White - OX	oxidizer	hydrogen peroxide, ammonium nitrate
White - W	Reacts with water in a dangerous or unusual way.	sulfuric acid, sodium
White - SA	simple asphyxiant gas	Only: nitrogen, helium, neon, argon, krypton, xenon

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Helmenstine, Anne Marie, Ph.D. "What Is NFPA 704 or the Fire Diamond?" ThoughtCo, Aug. 25, 2020, thoughtco.com/what-is-nfpa-704-or-the-fire-diamond-609000. Helmenstine, Anne Marie, Ph.D. (2020, August 25). What Is NFPA 704 or the Fire Diamond? Retrieved from https://www.thoughtco.com/what-is-nfpa-704-or-the-fire-diamond-609000 Helmenstine, Anne Marie, Ph.D. "What Is NFPA 704 or the Fire Diamond?" ThoughtCo. https://www.thoughtco.com/what-is-nfpa-704-or-the-fire-diamond-609000 (accessed March 29, 2023).