What type of containers must be treated as full containers even when empty?

Containers that have been used but are technically empty must be treated as full containers even when they appear to be empty because they can still contain residual propane or other flammable materials. It is critical to treat these containers as if they are still full to avoid potential hazards, such as the risk of fire or explosion, during handling, storage, or transportation. Regulations are in place to ensure safety because even a small amount of residue can be dangerous if ignited. This precaution helps to prevent accidents and ensures that safety protocols are followed when dealing with any propane-related equipment.

Other types of containers, like those that are pressurized or gauge containers, may have specific handling guidelines, but the key concern is the residual risk associated with containers that have held propane, emphasizing the need for caution and adherence to safety standards.