What does the NFPA 704 flammability (red) rating of 4 indicate?

• A. Will not burn
• B. Ignites at ambient temperatures
• C. Extremely flammable (gases/volatile liquids)
• D. Must be preheated to burn

Answer: (C)

The NFPA 704 flammability rating system provides important information about the fire hazard posed by materials. A rating of 4, indicated by the color red on the NFPA label, signifies that the material is extremely flammable, either as a gas or as a volatile liquid. This means that the substance can easily ignite and sustain combustion at normal ambient temperatures. The materials classified under this rating typically have flash points below 73°F (23°C), making them highly dangerous in situations where heat, sparks, or flames are present. Therefore, the correct interpretation of a flammability rating of 4 is that it indicates a significant fire risk, requiring careful handling and appropriate safety measures. Understanding this rating helps first responders and others manage hazardous situations effectively.