(1)
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(a) Ventilation ducts shall be of non-combustible
material. Short ducts, however, not generally exceeding 2 m in length
and with a cross section not exceeding 0.02 m2 need not
be non-combustible, subject to the following conditions:
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(i) these ducts shall be of a material which,
to the satisfaction of the Administration, has a low fire risk;
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(ii) they may only be used at the end of the ventilation
device; and
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(iii) they shall not be situated less than 600
mm, measured along the duct, from an opening in an "A" or "B" class
division including continuous "B" class ceilings.
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(b) Where the ventilation ducts with a free cross-sectional
area exceeding 0.02 m 2 pass through "A" class bulkheads
or decks, the openings shall be lined with a steel sheet sleeve unless
the ducts passing through the bulkheads or decks are of steel in the
vicinity of passage through the deck or bulkhead and comply in that
portion of the duet with the following:
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(i) for ducts with a free cross-sectional area
exceeding 0.02 m2 the sleeves shall have a thickness of
at least 3 mm and a length of at least 900 mm. When passing through
bulkheads this length shall preferably be divided evenly on each side
of the bulkhead. Ducts with a free cross-sectional area exceeding
0.02 m2 shall be provided with fire insulation. The insulation
shall have at least the same fire integrity as the bulkhead or deck
through which the duct passes. Equivalent penetration protection may
be provided to the satisfaction of the Administration; and
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(ii) ducts with a free cross-sectional area exceeding
0.085 m2 shall be fitted with fire dampers in addition
to the requirements of subparagraph (b)(i). The fire damper shall
operate automatically but shall also be capable of being closed manually
from both sides of the bulkhead or deck. The damper shall be provided
with an indicator which shows whether the damper is open or closed.
Fire dampers are not required, however, where ducts pass through spaces
surrounded by "A" class divisions, without serving those spaces, provided
those ducts have the same fire integrity as the bulkheads which they
penetrate.
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(c) Ventilation ducts for machinery spaces of
category A or galleys shall not in general pass through accommodation
spaces, service spaces or control stations. Where the Administration
permits this arrangement, the ducts shall be constructed of steel
or equivalent material and so arranged as to preserve the integrity
of the divisions.
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(d) Ventilation ducts of accommodation spaces,
service spaces or control stations shall not in general pass through
machinery spaces of category A or through galleys. Where the Administration
permits this arrangement the ducts shall be constructed of steel or
equivalent material and so arranged as to preserve the integrity of
the divisions.
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(e) Where ventilation ducts with a free cross-sectional
area exceeding 0.02 m2 pass through "B" class bulkheads
the openings shall be lined with steel sheet sleeves of at least 900
mm in length, unless the ducts are of steel for this length in way
of the bulkheads. When passing through a "B" class bulkhead this length
shall preferably be divided evenly on each side of the bulkhead.
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(f) Such measures as are practicable shall be
taken in respect of control stations outside machinery spaces in order
to ensure that ventilation, visibility and freedom from smoke are
maintained, so that in the event of fire the machinery and equipment
contained therein may be supervised and continue to function effectively.
Alternative and separate means of air supply shall be provided; air
inlets of the two sources of supply shall be so disposed that the
risk of both inlets drawing in smoke simultaneously is minimized.
At the discretion of the Administration, such requirements need not
apply to control stations situated on, and openings on to, an open
deck, or where local closing arrangements are equally effective.
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(g) Where they pass through accommodation spaces
or spaces containing combustible materials, the exhaust ducts from
galley ranges shall be constructed of A class divisions. Each exhaust
duct shall be fitted with:
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(i) a grease trap readily removable for cleaning;
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(ii) a fire damper located in the lower end of
the duct;
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(iii) arrangements, operable from within the galley,
for shutting off the exhaust fan; and
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(iv) fixed means for extinguishing a fire within
the duct, except where the Administration considers such fittings
impractical in a vessel of less than 75 m in length.
(2) The main inlets and outlets of all ventilation
systems shall be capable of being closed from outside the spaces being
ventilated. Power ventilation of accommodation spaces, service spaces,
control stations and machinery spaces shall be capable of being stopped
from an easily accessible position outside the space being served.
This position should not be readily cut off in the event of a fire
in the spaces served. The means provided for stopping the power ventilation
of the machinery spaces shall be entirely separate from the means
provided for stopping ventilation of other spaces.
(3) Means shall be provided for closing, from
a safe position, the annular spaces around funnels.
(4) Ventilation systems serving machinery spaces
shall be independent of systems serving other spaces.
(5) Store-rooms containing appreciable quantities
of highly flammable products shall be provided with ventilation arrangements
which are separate from other ventilation systems. Ventilation shall
be arranged at high and low levels and the inlets and outlets of ventilators
shall be positioned in safe areas and fitted with spark arresters.