NFPA 704
From PyroGuide
NFPA stands for National Fire Protection Association NFPA Website. The NFPA is an international nonprofit organization consisting of 81,000 members from all around the world and 80 national trade and professional organizations. Established in 1896 the organization is committed to "reduce the worldwide burden of fire and other hazards on the quality of life by providing and advocating consensus codes and standards, research, training, and education."
The NFPA has established thousands of codes to promote safety for the general public. Code 704 involves a quick and easy reference to determine the danger of hazardous chemicals. It is also referred to as a fire diamond.
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Description
Four color coded diamonds, creating one larger diamond, indicate the hazard of the material with a corresponding number between zero and four, for three of the diamonds. The fourth diamond usually contains a symbol or abbreviation for additional information or precautions for the material. The blue field represents the health hazard to humans, the red field a flammability hazard, the yellow field chemical reactivity/stability, and the white field for the special codes. Zeros represent a "safer" substance while a 4 represent the biggest risk. Some chemicals may have all zeros, but do not necessarily mean it is safe, in fact no chemical or compound, despite it's everyday usage should be considered safe. Even water can be poisonous. This is why a white field exists, to indicate oxidizers or water sensitive materials.
Blue - Health
* 4. Very short exposure could cause death or major residual injury (hydrogen cyanide). * 3. Short exposure could cause serious temporary or moderate residual injury (chlorine gas). * 2. Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury (chloroform). * 1. Exposure would cause irritation with only minor residual injury (turpentine). * 0. Poses no health hazard, no precautions necessary (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. These have a flash point below 23°C (73°F) (propane). * 3. Liquids and solids that can be ignited under almost all ambient temperature conditions. These have a flash point below 38°C (100°F) but above 23°C (73°F) (gasoline). * 2. Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. These have a flash point between 38°C (100°F) and 93°C (200°F) (diesel fuel). * 1. Must be pre-heated before ignition can occur. These have a flash point over 93°C (200°F). (soybean oil). * 0. Will not burn (water).
Yellow - Chemical Reactivity/Stability
* 4. Readily capable of detonation or explosive decomposition at normal temperatures and pressures (nitroglycerine, RDX) * 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 (fluorine). * 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). * 1. Normally stable, but can become unstable at elevated temperatures and pressures (acetylene (ethyne)). * 0. Normally stable, even under fire exposure conditions, and is not reactive with water (helium).
White - Special
*W: reacts with Water in an unusual or dangerous manner (cesium, sodium) * OX or OXY: Oxidizer (potassium perchlorate, ammonium nitrate) * COR: Corrosive; strong acid or base (sulfuric acid, potassium hydroxide) ** ACID and ALK to be more specific. * BIO: Biological hazard (smallpox virus) * POI: Poisonous (Spider Venom), * The Radioactive trefoil: is radioactive (plutonium, uranium) * CRY or CRYO: Cryogenic
Note: Only W and OX/OXY are officially part of the NFPA 704 standard, but other self-explanatory symbols are 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).