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DNV-OS-A101 Safety Principles and Arrangements
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Sec.6
F 300 General requirements
Sec.6 F
301 These requirements are in addition to the internal communication
system requirements found in the applicable statutory regulations.| — | The two way voice communication extensions at
control stations and the navigation bridge shall have priority. |
| — | The required internal communication systems shall be
capable of being supplied from the emergency source of power, for
a period of at least 18 hours. |
| — | The two-way voice communication
system shall be supplied by a battery or an uninterruptible power supply
as a stand-by power supply sufficient to operate the system for
at least 30 minutes. |
Sec.6 F
302 Alarms initiated from the following systems shall be provided
where relevant:| — | general emergency (ESD) or muster |
| — | fire detection |
| — | hydrocarbon gas detection |
| — | toxic gas (e.g. Hydrogen sulphide) detection |
| — | fire extinguishing medium release (CO2 or other gases with lethal
concentrations) |
| — | power-operated watertight door closing |
| — | machinery fault detection. |
Sec.6 F
303 All alarms shall be indicated visually and audibly in the
control centre.
Sec.6 F
304 An alarm philosophy shall be established ensuring that the
alarms are simple and unambiguous. The philosophy shall define which
alarms are broadcast to the entire unit or installation and whether
this should occur automatically or not.
Sec.6 F
305 The unit or installation shall be equipped with a public address
system. The alarm system may be combined with the public address
system, provided that:| — | alarms automatically override
any other input |
| — | volume controls are automatically set for alarm sounding |
| — | all parts of the public address system (e.g. amplifiers,
signal cables and loudspeakers) are made redundant |
| — | redundant parts are located or routed separately |
| — | all loudspeakers are protected with fuses against short
circuits. |
Sec.6 F
306 The number of alarms during abnormal conditions shall be assessed
and reduced as far as practicable by alarm processing/suppression
techniques in order to have operator attention on the most critical
alarms that require operator action.
Sec.6 F
307 The alarms shall be clearly audible at all locations on the
unit or installation, and shall be easily distinguishable. If noise
in an area prevents the audible alarm being heard a visible means
of alarm shall be provided.Guidance note:
See IMO Resolution A.830(19) Code
on Alarms and Indicators, 1995 for details on priorities,
grouping, locations and types, including colours, symbols etc.
National authorities may have specific requirements deviating
from the IMO Resolution. These will normally be acceptable for classification
purposes.---e-n-d---o-f---G-u-i-d-a-n-c-e---n-o-t-e---
Sec.6 F
308 Alarm to areas which are not regularly manned (e.g. cofferdams,
tanks) may be covered by procedural precautions, e.g. using portable
radios.
Sec.6 F
309 Activation of the general alarm shall be possible from the
main control stations, including navigation bridge and radio room.
Sec.6 F
310 In addition to the alarm systems, a two-way communication
system shall be provided for transmittal of alarm, instructions
and information between those who may require them.
Sec.6 F
311 The alarm and communication system shall be powered from the
main power system and from a monitored Uninterruptible Power Supply
(UPS) capable of at least 1 (one) hour continuous operation on loss of
main power. The UPS shall be powered from both the main and the
emergency power system.
Sec.6 F
312 Requirements for alarms in connection with watertight doors
and release of hazardous fire extinguishing medium are given in
DNV-OS-C301 and DNV-OS-D301.
Sec.6 F
313 The alarm system shall be regularly tested.
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