5.1 Required alerts should be clearly audible
and distinguishable in all parts of the spaces where they are required.
Where a distinct difference between the various audible signals and
calls cannot be determined satisfactorily, as in machinery spaces
with high ambient noise levels, it is permitted, to install common
audible signal and call devices supplemented by visual indicators
identifying the meaning of the audible signal or call.
5.2 The fire-extinguishing pre-discharge alarm
should have a characteristic which can be easily distinguished from
any other audible signal or call installed in the space(s) concerned.
Audible signals of fire and fire detection alarm should have a characteristic
which can be easily distinguished from any other audible signal or
call installed in the space(s).
5.3 Audible signals and calls should have characteristics
in accordance with section 7.
5.4 In large spaces, more than one audible signal
or call device should be installed, in order to avoid shock to persons
close to the source of sound and to ensure a uniform sound level over
all the space as far as practicable.
5.5 Facilities for adjusting the frequency of
audible signal within the prescribed limits may be provided to optimize
their performance in the ambient conditions. The adjustment devices
should be sealed, to the satisfaction of the Administration, after
setting has been completed.
5.6 Arrangements should not be provided to adjust
the sound pressure level of required audible signals. Where loudspeakers
with built-in volume controls are used, the volume controls should
be automatically disabled by the release of the alert signal.
5.7 Administrations may accept electronically-generated
signals, provided all applicable requirements herein are complied
with.
5.8 Administrations may accept the use of a public
address system for the general emergency alarm and the fire alarm
provided that:
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.1 all requirements for those alerts of the LSA Code, FSS Code and the 1974 SOLAS Convention, as amended, are met;
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.2 all the relevant requirements for required
alerts in this Code are met;
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.3 the system automatically overrides any other
input system when an emergency alarm is required and the system automatically
overrides any volume controls provided to give the required output
for the emergency mode when an emergency alarm is required;
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.4 the system is arranged to prevent feedback
or other interference; and
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.5 the system is arranged to minimize the effect
of a single failure.
5.9 The general emergency alarm, fire alarm (if
not incorporated in the general emergency alarm system), fire-extinguishing
medium alarm and machinery alarm should be so arranged that the failure
of the power supply or the signal-generating and amplifying equipment
(if any) to one will not affect the performance of the others. Where
common audible signals and call devices are installed in accordance
with 5.1, arrangements should be provided to minimize the effect of
such devices’ failure.
5.10 The performance standards and functional
requirements of the general emergency alarm are specified in the LSA Code, chapter VII, section 7.2. In addition,
the sound pressure level should be in the 1/3-octave band about the
fundamental frequency. In no case should the level of an audible signal
in a space exceed 120 dB(A).
5.11 With the exception of bells, audible signals
should have a signal frequency between 200 Hz and 2,500 Hz.
5.12 For the audible presentation of alerts on
the navigation bridge, the requirements of resolution
MSC.191(79), MSC/Circ.982, resolution
A.694(17) and module C of resolution
MSC.252(83) where applicable to ships with Integrated Navigation
Systems (INS), and, where fitted, the requirements of a bridge alert
management system, should be observed.
5.13 For the audible presentation of navigational
alerts on the bridge the sound pressure should be at least 75 dB(A)
but not greater than 85 dB(A) at a distance of one metre from the
systems. Alternatively, it may be allowed to adjust the sound pressure
to at least 10 dB(A) above the ambient noise level instead, if the
ambient sound pressure on the bridge can be determined. The upper
noise level should not exceed 85 dB(A).