Which class of flammable liquids is not permitted to be stored in basements?

Class I flammable liquids are defined by the National Fire Protection Association (NFPA) as having a flash point below 100 degrees Fahrenheit (37.8 degrees Celsius). These liquids are highly volatile and capable of generating flammable vapors at relatively low temperatures. Due to their dangerous characteristics, storing Class I liquids in basements is not permitted. Basements often have limited ventilation and may accumulate flammable vapors, increasing the risk of fire or explosion.

In contrast, Class II and Class III liquids have higher flash points, which makes them less volatile and generally safer for storage under certain conditions. Class II liquids have a flash point between 100 and 140 degrees Fahrenheit (37.8 to 60 degrees Celsius), and Class III liquids have a flash point of 140 degrees Fahrenheit or above. These classifications indicate that they pose a lower risk of ignition compared to Class I liquids, allowing for more flexibility in storage options. Class IV liquids, likewise, are characterized by even higher flash points and are deemed even safer for storage in various environments.

Given the hazardous nature of Class I liquids and the specific safety guidelines outlined in fire codes and standards, a clear prohibition on their storage in basements aims to minimize risk and protect life and property.