What classification does the NFPA assign to flammable liquids?

The classification assigned by the National Fire Protection Association (NFPA) to flammable liquids is indeed Class I. This category encompasses liquids that have flash points below 100°F (37.8°C). Flash point is a critical property that indicates the lowest temperature at which a liquid can form an ignitable mixture in air. Flammable liquids are particularly hazardous because they can ignite easily at relatively low temperatures, posing significant risks in both storage and handling scenarios.

Class I is further divided into three subcategories based on the specific flash point ranges: Class IA for liquids with flash points below 73°F and boiling points below 100°F, Class IB for liquids with flash points below 73°F and boiling points at or above 100°F, and Class IC for liquids with flash points between 73°F and 100°F.

By definition, Class II pertains to liquids that have flash points between 100°F and 140°F, while Class III encompasses liquids with flash points at or above 140°F. Combustible solids and classifications concerning non-flammable materials fall outside the typical categorization of flammable liquids altogether, reinforcing why Class I is the appropriate classification for flammable liquids according to NFPA standards.