46 CFR § 153.438 - Cargo pressure or temperature alarms required.
(a) Each refrigerated tank must have:
(1) An alarm that operates when the cargo's pressure exceeds the vapor pressure described in § 153.371(b); or
(2) An alarm that operates when the cargo's temperature exceeds the steady state temperature described in § 153.371(b).
(b) The alarm must give an audible and visual signal on the bridge and at the cargo control station.
(c) The cargo pressure or temperature alarm must be independent of other cargo pressure or temperature sensing arrangements.