Hazardous material classification from a safety data sheet.

A safety data sheet speaks GHS. The fire code speaks IFC. They bin the same numbers differently.

The hazard statements in section 2 of a safety data sheet come from the Globally Harmonized System, and the fire code does not use them. The International Fire Code defines its own hazard categories in Section 202, and those definitions decide the maximum allowable quantity per control area, the occupancy group a building becomes when the quantity is exceeded, and the operational permit. The two systems cut the same measurements at different places: GHS sorts flammable liquids by flash points in Celsius, the IFC by 73, 100, 140 and 200 degrees Fahrenheit, so no GHS category maps onto exactly one IFC class, and a Class IIIB combustible liquid is invisible to GHS altogether.

So the numbers decide first. A flash point and a boiling point from section 9 place a liquid in its class; the LD50 and LC50 figures in section 11 place it among the toxic or highly toxic materials; the hazard statements are the fallback when a number is missing and the cross-check when it is not. When the two disagree, the answer says so and uses the number, because the classification the code asks for is the measured one.

Some categories cannot be settled from the sheet alone, and the answer says what decides each. A liquid whose boiling range starts below 100 degrees and ends above it could be Class IA or IB, and the code reads a mixture's boiling point as the 20 percent point of a distillation that a sheet rarely prints. The class of an oxidizer, an organic peroxide, an unstable reactive or a water reactive material is a judgment about how it burns or reacts. And an inhalation LC50 from a four-hour test is lower than the one-hour figure the code's toxicity bands are written in.

What a sheet never establishes is the form the material is in: combustible dust and combustible fibers depend on particle size and handling, not on the chemical.