The common HazMat "Diamond" is technically known as the National Fire Prevention Association standard 704 for the classification of hazardous materials. It is a standard hazard rating system which provides a readily recognized, easily understood system for identifying specific hazards and their severity using spatial, visual, and numerical methods to describe in simple terms the relative hazards of a material. It addresses the health, flammability, instability, and related hazards that may be presented as short-term, acute exposures that are most likely to occur as a result of fire, spill, or similar emergency.
Meaning of Colors
The hazards are arranged spatially as follows: health at nine o'clock position, flammability at 12 o'clock position, and instability at 3 o'clock position. In addition to the spatial orientation that can be used to distinguish the hazards, they are also color coded as follows.
Red for flammability
||Material that will not burn |
||Material that must be pre-heated before ignition can occur |
||Material that must be moderately heated or exposed to relatively high ambient temperature before ignition can occur |
||Liquids and solids that can be ignited under almost all ambient temperature conditions |
||Materials that will rapidly or completely vaporize at atmospheric pressure and normal ambient temperature, or that are readily dispersed in air and that will burn readily |
Yellow for reactivity
||Material that in itself is normally stable, even under fire exposure conditions, and is not reactive with water|
||Material that in itself is normally stable, but which can become unstable at elevated temperatures and pressures|
||Material that readily undergoes violent chemical change at elevated temperatures and pressures, that reacts violently with water, or that may form explosive mixtures with water|
||Material that in itself is capable of detonation or explosive decomposition or reaction, but requires a strong initiating source, that must be heated under confinement before initiation, or that reacts explosively with water|
||Material that in itself is readily capable of detonation, or of explosive decomposition, or reaction at normal temperatures and pressures|
Blue for health hazard
||Material that, on exposure under fire conditions, would offer no hazard beyond that of ordinary combustible material.|
||Material that, on exposure, would cause irritation but only minor residual injury|
||Material that, on intense or continued but not chronic exposure, could cause temporary incapacitation or possible residual injury|
||Material that, on short exposure, could cause serious temporary or residual injury|
||Material that, on very short exposure, could cause death or major residual injury|
White for health hazard (W-Water Reactive, OX-Oxidizer)
||Material shows unusual reactivity with water (i.e., don't put water on it)|
||Material possesses oxidizing properties|
||Material is an acid|
||Material is a base (alkaline)|
||Material is corrosive|
Material is radioactive
Hazard severity is indicated by a numerical rating that ranges from zero (0) indicating a minimal hazard, to four (4) indicating a severe hazard.
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