(1) Ventilation ducts shall be of non-combustible material. Short ducts, however not generally exceeding 2 meters in length and with a cross-section not exceeding 0.02m need not be non-combustible, subject to the following conditions.
(a) The dusts shall be of a material which has a low fire risk.
(b) They may only be used at the end of the ventilation device.
(c) They shall not be situated less than 600 mm measured along the duct from an opening in a A or B class division including continuous B class ceilings.
(2) Where the ventilation ducts with a free-sectional area exceeding 0.02 m pass through class A bulkheads or decks the opening shall be lined with a steel sheet sleeve, unless the ducks passing through the bulkhead or decks are of steel in the vicinity of passage through the deck of bulkhead and the ducts and sleeves shall comply with the following-
(a)The sleeves shall have a thickness of at least 3 mm and a length of at least 900 mm. When passing through bulkheads, such length shall be divided preferably into 450mm on each side of the bulkhead. These ducts, or sleeves lining such ducts 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 passed. Equivalent penetration protection may be provided to the satisfaction of the Chief Surveyor with the Government of /India.
(b) Ducts with a free cross-sectional area exceeding 0.075m shall be fitted with fire dampers in addition to the requirements of clause.