What qualifies a liquid as a highly volatile liquid according to NFPA 1?

A highly volatile liquid, as defined by NFPA 1, is characterized by its boiling point, which significantly influences its behavior in fire scenarios. A liquid with a boiling point of less than 68 degrees Fahrenheit is deemed as highly volatile because it readily evaporates at temperatures that are common in many environments. This low boiling point means that the liquid can turn into vapor quickly, potentially leading to a buildup of flammable vapors in the air, which presents a fire hazard.

In fire safety terms, understanding the volatility of liquids is crucial for assessing risk and implementing appropriate safety measures. Highly volatile liquids can ignite at lower temperatures, increasing the urgency for proper storage, handling, and transportation to prevent accidents.

The other options provide boiling point thresholds that do not align with the NFPA 1 classification for highly volatile liquids. Therefore, the correct option identifies the crucial temperature limit that distinguishes highly volatile liquids, aligning with recognized safety standards.