46 CFR § 169.734
Fire extinguishing system controls
April 15, 2021
Each control cabinet or space containing valves or manifolds for the various fire extinguishing systems must be distinctly marked in conspicuous red letters at least 2 inches high: “CARBON DIOXIDE FIRE EXTINGUISHING SYSTEM,” “HALON EXTINGUISHING SYSTEM,” or “CLEAN AGENT EXTINGUISHING SYSTEM,” as appropriate.
[USCG-2006-24797, 77 FR 33890, June 7, 2012]