Mixing of agents in the same container is permitted only if the system is which?

• A. Listed
• B. Approved
• C. Installed
• D. Certified

Answer: (A)

Mixing different clean agent types in the same container is allowed only when the system is listed. A listing means a recognized testing laboratory has evaluated the system and specifically approved that the combination in one cylinder is safe and compatible for use. This formal testing and documentation ensures the agents will remain stable, perform as intended, and not create unsafe conditions like unexpected pressure changes or adverse chemical reactions. Without a listing, there isn’t verified evidence that mixing is safe, so it’s not permitted. Other terms like approval, installation, or certification don’t provide the same validated assurance for this practice.