6.2 The electrical power required for power-operated sliding watertight doors
shall be supplied from the emergency switchboard either directly or by a dedicated
distribution board situated above the bulkhead deck. The associated control,
indication and alarm circuits shall be supplied from the emergency switchboard either
directly or by a dedicated distribution board situated above the bulkhead deck and be
capable of being automatically supplied by the transitional source of emergency
electrical power required by regulation 42.3.1.3 in the event of failure of either the
main or emergency source of electrical power.
6.3 Power-operated sliding watertight doors shall have either:
.1 a centralized hydraulic system with two independent power sources
each consisting of a motor and pump capable of simultaneously
closing all doors. In addition, there shall be for the whole installation
hydraulic accumulators of sufficient capacity to operate all the doors
at least three times, i.e. closed-open-closed, against an adverse list
of 15°. This operating cycle shall be capable of being carried out when
the accumulator is at the pump cut-in pressure. The fluid used shall
be chosen considering the temperatures liable to be encountered by
the installation during its service. The power-operating system shall
be designed to minimize the possibility of having a single failure in the
hydraulic piping adversely affect the operation of more than one door.
The hydraulic system shall be provided with a low-level alarm for
hydraulic fluid reservoirs serving the power-operated system and a
low gas pressure alarm or other effective means of monitoring loss of
stored energy in hydraulic accumulators. These alarms are to be
audible and visual and shall be situated on the central operating
console(s) required by paragraph 7.1; or
.2 an independent hydraulic system for each door with each power
source consisting of a motor and pump capable of opening and
closing the door. In addition, there shall be a hydraulic accumulator
of sufficient capacity to operate the door at least three times, i.e.
closed-open-closed, against an adverse list of 15
°
. This operating
cycle shall be capable of being carried out when the accumulator is
at the pump cut-in pressure. The fluid used shall be chosen
considering the temperatures liable to be encountered by the
installation during its service. A low gas pressure group alarm or
other effective means of monitoring loss of stored energy in
hydraulic accumulators shall be provided at the central operating
console(s) required by paragraph 7.1. Loss of stored energy
indication at each local operating position shall also be provided; or
.3 an independent electrical system and motor for each door with each
power source consisting of a motor capable of opening and closing
the door. The power source shall be capable of being automatically
supplied by the transitional source of emergency electrical power as
required by regulation 42.4.2 – in the event of failure of either the
main or emergency source of electrical power and with sufficient
capacity to operate the door at least three times, i.e.
closed-open-closed, against an adverse list of 15
°
.
For the systems specified in paragraphs 6.3.1, 6.3.2 and 6.3.3, provision should be
made as follows: Power systems for power-operated sliding watertight doors shall be
separate from any other power system. A single failure in the electric or hydraulic
RESOLUTION MSC.474(102) (adopted on 11 November 2020)
AMENDMENTS TO THE INTERNATIONAL CONVENTION FOR THE SAFETY OF LIFE AT SEA, 1974