Page 367 - Ship Construction.DJ Eyres 6Ed

Ch32-H8070.fm Page 356 Wednesday, October 18, 2006 7:06 AM
356 Ship Construction
self-closing against an inclination of 3½° opposing closure. Such doors are
capable of closure from a control station either simultaneously or in groups
and also individually from a position adjacent to the door. Vent trunking
runs are ideally contained within one fire zone but where they must pass
through a main fire zone bulkhead or deck a fail safe automatic-closing fire
damper is fitted within the trunk adjacent to the bulkhead or deck. This
usually takes the form of a steel flap in the trunk which is held open by a
--- ใช้เพื่อการศึกษาเท่านั้น---
weighted hinge secured by an external fusible link. The flap must also be
capable of being released manually and there is some form of indication as
to whether the flap is open or closed (see Figure 32.1).
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี

Protection of Special Category Spaces

A special category space is an enclosed space above or below the bulkhead
deck used for the carriage of motor vehicles with fuel for their own pro-
pulsion in their own tanks and to which passengers have access. Obvious
examples are the garage spaces in ro-ro passenger ferries and vehicle decks
in ro-ro cargo ships. Such spaces cannot have the normal main vertical fire
zoning without interfering with the working of the ship.
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Equivalent protection is provided in such spaces by ensuring that the
horizontal and vertical boundaries of the space are treated as main fire
zone divisions and an efficient fixed fire-extinguishing system is fitted within
the space. This takes the form of a fixed pressure water spraying system
generally in association with an automatic fire detection system. Special
scupper arrangements are provided to clear the deck of the water deposited by
the system in the event of a fire to avoid a drastic reduction in stability.

Fire Protection Arrangements in High Speed Craft

The IMO High Speed Craft Code (HSC Code) recognizes the use of light-
weight construction materials such as aluminium alloy and fibre reinforced
plastics which have a lesser fire rating than steel. Consequently, that Code
has applied a new approach to fire insulation to that taken by SOLAS for
conventional steel ships. The HSC Code has introduced the concept of a
‘fire restricting material’ which may be a combustible material or combi-
nation of combustible materials provided it can comply with a prescribed
fire test limiting heat release, smoke production and spread of flame. Also
introduced is the concept of a ‘fire resisting division’ to prevent flame
spread from one compartment to another within a prescribed time which is
related to a passenger evacuation time for the craft. A fire resisting division
can be constructed from non-combustible material, fire resisting material
or a combination of both.