🔍 Key Concepts

• Residue/empty container requirements under 49 CFR for hazardous materials that have not been cleaned or purged • Difference between a label (for smaller packages) and a placard (for large bulk containers/vehicles) • How long a hazard class placard remains required when there is still residue or vapor of a corrosive liquid

💭 Think About

• Ask yourself: Is a tank container that is "empty but not cleaned" still considered to contain hazardous material for placarding purposes? • Consider whether a sodium hydroxide solution is classified as a corrosive material and what standard placard is associated with that hazard class. • Think about whether simply sealing the openings changes the placarding requirement if residue remains inside.

✅ Before You Answer

• Verify whether an "empty" tank that still contains residue or vapor is treated the same as a loaded tank for placarding rules. • Confirm the standard placard used for corrosive materials such as sodium hydroxide solution. • Check whether a separate "residue" or "empty" placard/label is required or even exists in standard placarding practice.