Which NFPA 704 rating indicates that a substance won't burn?

• A. 1
• B. 2
• C. 3
• D. 0

Answer: (D)

The NFPA 704 rating system is used to identify the hazards associated with materials, particularly in emergency situations. In this system, each hazard is assigned a numerical rating from 0 to 4, with 0 indicating no hazard and 4 indicating a severe hazard.

A rating of 0 in the flammability category specifically indicates that a substance will not burn under normal conditions. This rating is assigned to materials that are non-combustible and present no fire hazard, meaning they won’t ignite or support combustion. Materials with this rating can include water, certain metals, and other substances that do not have flammable properties.

In contrast, the other ratings (1, 2, and 3) represent increasing levels of flammability, indicating that the substances can ignite and burn under various conditions, with 1 being the least hazardous and 4 being extremely hazardous. Understanding these ratings is crucial for first responders to assess risks quickly and act appropriately in hazardous situations.