Appendix E

National Fire Protection Association (NFPA) Identification Codes

Health Ratings

4	Materials that, under emergency conditions, can be lethal.
3	Materials that, under emergency conditions, can cause serious or permanent injury.
2	Materials that, under emergency conditions, can cause temporary incapacitation or residual injury.
1	Materials that, under emergency conditions, can cause significant irritation.
0	Materials that, under emergency conditions, would offer no hazard beyond that of ordinary combustible materials.

Flammability Ratings

4	Materials that will rapidly or completely vaporize at atmospheric pressure and normal ambient temperature or that are readily dispersed in air, and which will burn readily.
3	Liquids and solids that can be ignited under almost all ambient temperature conditions. Materials in this degree produce hazardous atmospheres with air under almost all ambient temperatures or, though unaffected by ambient temperatures, are readily ignited under almost all conditions.
2	Materials that must be moderately heated or exposed to relatively high ambient temperatures before ignition can occur. Materials in this degree would not under normal conditions form hazardous atmospheres with air, but under high ambient temperatures or under moderate heating might release vapor in sufficient quantities to produce hazardous atmospheres with air.
1	Materials that must be preheated before ignition can occur. Materials in this degree require considerable preheating, under all ambient temperature conditions, before ignition and combustion can occur.
0	Materials that will not burn. This includes any material that will not burn in air when exposed to a temperature of 1500°F (815.5°C) for period of 5 minutes.

Instability Ratings

4	Materials that in themselves are readily capable of detonation or explosive decomposition or explosive reaction at normal temperatures and pressures. This includes materials which are sensitive to localized thermal or mechanical shock at normal temperatures and pressures.
3	Materials that in themselves are capable of detonation or explosive decomposition or explosive reaction but that require a strong initiating source or that must be heated under confinement before initiation.
2	Materials that readily undergo violent chemical change at elevated temperatures and pressures.
1	Materials that in themselves are normally stable but that can become unstable at elevated temperatures and pressures.
0	Materials that in themselves are normally stable, even under fire conditions.

Special Hazards

Properties of the material that cause special problems or require special fire-fighting techniques.

Materials that demonstrate unusual reactivity with water shall be identified by the letter W with a horizontal line through it.

Materials that possess oxidizing properties shall be identified with the letters OX.

Additional information on the definitions of the hazard ratings can be obtained from NFPA 704, Standard System for the Identification of the Hazards of Materials for Emergency Response.