NFPA 704 Totally Explained

NFPA 704 is a standard maintained by the U.S. 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.

Symbolism

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).

Blue/Health

4. Very short exposure could cause death or major residual injury (for example, hydrogen cyanide).
3. Short exposure could cause serious temporary or residual injury (for example, chlorine gas).
2. Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury (for example, chloroform).
1. Exposure would cause irritation with only minor residual injury (for example, turpentine).
0. Poses no health hazard, no precautions necessary. (for example, lanolin).

Red/Flammability

4. Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily (for example, propane). Flash point below 23°C (73°F).

3. Liquids and solids that can be ignited under almost all ambient temperature conditions (for example, gasoline). Flash point below 38°C (100°F) but above 23°C (73°F).

2. Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur (for example, diesel fuel). Flash point between 38°C (100°F) and 93°C (200°F).

1. Must be pre-heated before ignition can occur (for example, canola oil). Flash point over 93°C (200°F).

0. Will not burn (for example, Argon).

Yellow/Reactivity

4. Readily capable of detonation or explosive decomposition at normal temperatures and pressures (for example, trinitrotoluene).

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 (for example, fluorine).

2. Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water (for example, phosphorus).

1. Normally stable, but can become unstable at elevated temperatures and pressures (for example, calcium).

0. Normally stable, even under fire exposure conditions, and isn't reactive with water (for example, helium).

White/Special

The white "banda" area can contain several symbols:

'W' - reacts with water in an unusual or dangerous manner (for example cesium, sodium)

'OXY' - oxidizer (for example potassium perchlorate)

'COR' - corrosive; strong acid or base (for example sulfuric acid, potassium hydroxide)

'ACID' and 'ALK' to be more specific.

'BIO' - Biohazardous (for example smallpox virus)

The radioactive trefoil - is radioactive (for example plutonium)

'CRYO' - Cryogenic Note: Only 'W' and 'OXY' are officially part of the NFPA 704 standard, but other self-explanatory symbols are occasionally used in an unofficial manner.

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