As per SOLAS chapter II-2, regulation 7
- Ventilation ducts shall be of non-combustible material. However, short ducts, not generally exceeding 2 m in length and with a free cross sectional area* not exceeding 0.02 m2, need not be non-combustible, subject to the following conditions:
- The ducts are made of a material which has low flame-spread characteristics;
- The ducts are only used at the end of the ventilation device; and
- The ducts are not situated less than 600 mm, measured along the duct, from an opening in an ‘‘A’’ or ‘‘B’’ class division, including continuous ‘‘B’’ class ceiling.
- The following arrangements shall be tested in accordance with the Fire Test Procedures Code:
- Fire dampers, including their relevant means of operation; and
- Duct penetrations through ‘‘A’’ class divisions. However, the test is not required where steel sleeves are directly joined to
- ventilation ducts by means of riveted or screwed flanges or by
- welding.
- Arrangement of ducts
- The ventilation systems for machinery spaces of category A, vehicle spaces, ro–ro spaces, galleys, special category spaces and cargo spaces shall, in general, be separated from each other and from the ventilation systems.
- serving other spaces, except that the galley ventilation systems on cargo ships of less than 4,000 gross tonnage and in passenger ships carrying not more than 36 passengers need not be completely separated.
- Except in cargo spaces, ventilation ducts shall be constructed of the following materials:
- ducts not less than 0.075 m2 in free cross-sectional area and all
- vertical ducts serving more than a single ’tween-deck space shall
- be constructed of steel or other equivalent material.
