46 CFR §95.15-30

1. (a)A protected space must be fitted with an approved audible alarm if:
   1. (1)The space is normally accessible to persons onboard while the vessel is being navigated; and
   2. (2)Is not a paint locker or similar small space.
2. (b)The alarm must:
   1. (1)Sound automatically and audibly for at least 20 seconds before carbon dioxide is discharged into the space;
   2. (2)Be conspicuously and centrally located and be marked as required by 46 CFR 97.37-9; and
   3. (3)Use stored gas power provided by the extinguishing agent, gas from pilot cylinders, or gas from cylinders specifically provided to power the alarms.
3. (c)For systems installed on or after July 1, 1957, alarms are mandatory only for systems required to be fitted with a delayed discharge.