UN 1017 — chlorine

UN 1017 is chlorine. The placard is class 2.3, a gas poisonous by inhalation. Chlorine cars are pressure tanks, and the industry treats them as a distinct service.

The number 1017 is the whole identification a spotter needs to write down. "Green tank car" is not an identification. Chlorine's reputation is the reason the number exists, so use the number.

A leaking chlorine car is an emergency, not a photograph. The response guidebook, not this page, is what firefighters use.