Class

The NFPA system for flammable and combustible liquids is given in NFPA 30. Class I flammable liquids have closed-cup flash points below 100°F (37.8°C) and Reid vapor pressures not exceeding 40 psia (2068.6 mmHg) at 100°F (37.8°C). Class I flammable liquids are further classified as follows. Class 1A liquids have flash points below 73°F (22.8°C) and boiling points below 100°F (37.8°C). Class IB liquids have flash points below 73°F (22.8°C) and boiling points at or above 100°F (37.8°C). Class IC liquids have flash points at or above 73°F (22.8°C) but below 100°F (37.8°C). Combustible liquids have closed cup flash points at or above 100°F (37.8°C) and are subdivided into Class II and Class III as follows. Class II liquids have flash points at or above 100°F (37.8C) but below 140°F (60C). Class IIIA liquids have flash points at or above 140°F (60°C) but below 200°F (93°C). Class IIIB liquids have flash points at or above 200°F (93°C). The DOT system for flammable and combustible liquids is given in 49CFR Part 173. Disregarding special cases, flammable liquids have flash points of not more than 60.5°C (141°F) and combustible liquids have flash points above 60.5°C (141°F) and below 93°C (200°F).