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NFPA 704
NFPA 704.svg
Fire diamond for Sodium borohydride

NFPA 704 is a standard maintained by the U.S.-based National Fire Protection Association. It defines the colloquial "fire diamond" used by emergency personnel to quickly and easily identify the risks posed by nearby hazardous materials. This is necessary to help determine what, if any, specialty equipment should be used, procedures followed, or precautions taken during the first moments of an emergency response.



The four divisions are typically color-coded, with blue indicating level of health hazard, red indicating flammability, yellow (chemical) reactivity, and white containing special codes for unique hazards. Each of health, flammability and reactivity is rated on a scale from 0 (no hazard; normal substance) to 4 (severe risk).

Health (Blue) Flammability (Red)
4 Very short exposure could cause death or major residual injury (e.g., hydrogen cyanide, phosphine) 4 Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily (e.g., propane). Flash point below 23°C (73°F)
3 Short exposure could cause serious temporary or moderate residual injury (e.g., chlorine gas) 3 Liquids and solids that can be ignited under almost all ambient temperature conditions (e.g., gasoline). Flash point between 23°C (73°F) and 38°C (100°F)
2 Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury (e.g., ethyl ether) 2 Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur (e.g., diesel fuel). Flash point between 38°C (100°F) and 93°C (200°F)
1 Exposure would cause irritation with only minor residual injury (e.g., acetone) 1 Must be heated before ignition can occur (e.g., soybean oil). Flash point over 93°C (200°F)
0 Poses no health hazard, no precautions necessary. (e.g., lanolin) 0 Will not burn (e.g., water)
Instability/Reactivity (Yellow) Special (White)
4 Readily capable of detonation or explosive decomposition at normal temperatures and pressures (e.g., nitroglycerine, RDX)   The white "special notice" area can contain several symbols. The following symbols are defined by the NFPA 704 standard:
3 Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked (e.g. ammonium nitrate) W Reacts with Water in an unusual or dangerous manner (e.g., caesium, sodium)
2 Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water (e.g., phosphorus, potassium, sodium) OXY Oxidizer (e.g., potassium perchlorate, ammonium nitrate, hydrogen peroxide)
1 Normally stable, but can become unstable at elevated temperatures and pressures (e.g. propene) SA Simple asphyxiant gas (includes nitrogen, helium, neon, argon, krypton, and xenon)
0 Normally stable, even under fire exposure conditions, and is not reactive with water (e.g. helium)    
Two plastic squirt bottles labeled with the NFPA 704 color code for hazardous materials identification.

Non-Standard Symbols

Note: These symbols are not part of the NFPA 704 standard, but occasionally used in an unofficial manner. The use of non-standard symbols or text may be permitted, required or disallowed by the authority having jurisdiction (e.g., fire department).

See also


External links


Simple English

NFPA 704, also known as a fire diamond, is a diamond that is used by firemen and emergency people to know about the hazards of a chemical compound. It consists of a blue little diamond on the left, a red one on the top, a yellow one on the right, and a white one on the bottom. The blue one measures the health hazard of the chemical. The red one measures the flammability (ease of catching fire) of the chemical. The yellow one measures the reactivity of the chemical with other chemicals. The white one is for special hazards, such as reaction with water. The higher the number, the more hazardous the chemical is. For example, sodium chloride is 1-Health (mildly irritating), 0-Flammability (does not burn), 0-Reactivity (does not react dangerously). By comparison, nitroglycerin is 3-Health (very hazardous), 3-Flammability (catches on fire easily), 4-Reactivity (extremely reactive).

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