The Safe Return to Port amendment is intended to secure that a vessel remains functional even in the case of fire or flooding in one compartment and is able to return safely to port without the need to abandon ship.
The regulations are mandatory for passenger ships having a length of 120 metres or more or having three or more main vertical zones. These vessels have to be able to return to port after a casualty case, not exceeding a defined flooding or fire casualty threshold, and provide all persons on board basic services in so-called ‘safe areas’. For fire casualty cases exceeding the casualty threshold but not exceeding one main vertical fire zone, systems for supporting orderly evacuation have to be available for 3 hours.
The low-pressure water mist solution
The control system consists of two CPUs, each with its own program. Machinery space systems are hardwired with redundant zone valves. Manual release buttons have inputs to both CPUs.
Accommodation system zone monitoring is connected to the Ethernet ring via IE/As-I link modules.
Operation / Indication are carried out by minimum two touch screens connected to the Ethernet ring. In normal operation, the main CPU is controlled. Change-over to the back-up CPU is carried out automatically or manually from either of the touch screens.
Each of the pump packages has a 100% capacity and is connected to its own dedicated sea chest. The pump package is common for both accommodation and machinery space systems, i.e. it is not necessary to have separate pumps for each of the applications. The pump units is located in the foremost and aftmost main vertical zone.
Zone valves for machinery space protection have 100% redundancy and should be located at the pump station. Zone valves for accommodation are normally located outside the protected fire zone within a dedicated A0 enclosure, i.e. duplicate zone valves are not required. If located outside A0 enclosure, the zone valves has to be duplicated..
Low-pressure water mist system for protection of accommodation area, machinery space cat. A and pump rooms, and local protection, machinery space cat. A. If local protection is separate, i.e. not a part of the total flooding system, SRTP requirements are not required.