Section 40 in The Merchant Shipping (Fire Appliances) Rules, 1969
40. Smothering gas and steam installation.
(1)Where provision is made for the injection of gas or steam into machinery or cargo spaces for fire extinguishing purposes, the necessary pipes for conveying the gas or steam shall be provided with control valves or cocks which shall be so placed that they will be easily accessible and not readily cut off from use by an outbreak of fire. Such control valves or cocks shall be so marked as to indicate clearly the compartments to which the pipes are laid. Suitable provision shall be made to prevent inadvertant admission of the gas or steam to any compartment. Where cargo spaces fitted with smothering gas for fire protection are used as passenger spaces the smothering gas or steam pipe connection shall be blanked during service as a passenger space.(2)The piping shall be so arranged as to distribute the smothering gas or steam in an effective manner. In holds over 20 metres in length at least two pipes shall be provided in cargo space one at each end of the hold, i.e., one on the forward side and the other on the after part. Except in tankers and ships used for the conveyance of coal, pipes for conveying steam shall be fitted with Outlets as low as practicable in the space which they serve and as nearly as possible to the centre line of the space.(3)In tankers, the piping system shall be so arranged that the smothering gas when discharged, will be distributed over the surface of the cargo.(4)Where a generator producing inert gas is used to provide smothering gas in the fixed smothering installation for cargo spaces, it shall be capable of producing hourly a volume of free gas equal to 25 per cent of the gross volume of the largest compartment protected in this way for a period of 72 hours.(5)When steam is used as an extinguishing medium in cargo spaces, the boilers available for supplying steam shall have an evaporation of at least one kilogramme of steam per hour for each 0.75 cubic metre of the gross volume of the largest cargo compartment in the ship. The steam shall be available in the required quantity whenever needed during the course of the voyage and for this purpose suitable provision by way of extra feed water shall be made.(6)When carbon dioxide is used as an extinguishing medium--(i)if discharged into space containing boilers or internal combustion type of machinery, the quantity of gas available shall be sufficient to give a minimum quantity of free gas to larger of the following quantities, namely, either---------a volume to include the casing tip to the level at which the(a)40 per cent of the gross volume of the largest space, such horizontal area of the casing is 40 per cent or less of the space concerned; or(b)35 per cent of the entire volume of the largest space including the casing :Provided that the above mentioned percentages maybe reduced to 35 per cent or 30 per cent, as the case may be, in the case of cargo ships of less than 2000 tons :Provided further that if two or more spaces containing boilers or internal combustion type of machinery are not entirely separate, they shall be deemed as forming one compartment;(ii)if discharged into cargo spaces, the quantity of gas available shall be sufficient to give a minimum volume of free gas equal to 30 per cent of the gross volume of the largest cargo compartment in the ship which is capable of being sealed;(iii)if discharged into both cargo spaces and spaces containing boilers or internal combustion type of machinery, the quantity of gas need not be more than the maximum required either for the largest cargo compartment or machinery spaces;(iv)if discharged into spaces containing boilers or internal combustion type of machinery, the fixed piping system shall be such that 88 per cent of the gas shall be capable of being discharged into such spaces within two minutes.(7)For the purpose of determining the quantity of liquid carbon dioxide required to produce the volume of smothering gas required under these rules, 1 kg. of liquefied carbon dioxide shall be deemed to produce 0.56 cubic metres of gas.(8)Adequate means shall be provided for giving audible warning when carbon dioxide is about to be released into any working spaces.(9)When carbon dioxide is used as the extinguishing medium in spaces containing boilers or oil fuel installations a quantity of gas which can be discharged normally without danger to the operator shall be available near the oil fuel unit.
