UN 1789 — hydrochloric acid

UN 1789 is hydrochloric acid, also called muriatic acid in other settings. On a railcar the placard is class 8, corrosive. The number is what distinguishes it from sulfuric acid and from caustic soda, which share the class and not the chemistry.

Acid cars often show extra stencils about the lining or the commodity service. Those notes are about the tank's preparation. 1789 is about the load.

Corrosive means the material attacks tissue and metal. It does not mean "flammable." If a car carries both a class 8 placard and another class placard, write down both. Some shipments earn more than one.