46 CFR § 97.37-13
Fire extinguishing system controls
April 15, 2021
The control cabinets or spaces containing valves or manifolds for the various fire extinguishing systems must be distinctly marked in conspicuous red letters at least 2 inches high: “[STEAM/CARBON DIOXIDE/CLEAN AGENT/FOAM/WATER SPRAY—as appropriate] FIRE APPARATUS.”.
[USCG-2006-24797, 77 FR 33881, June 7, 2012]