71Requirements of gas fire-smothering piping systems for boiler rooms etc

71 Requirements of gas fire-smothering piping systems for boiler rooms etc

(1) Subject to this regulation, when carbon-dioxide is used in a piping system for the purpose of providing a fire-smothering gas to be discharged into a space or spaces containing boilers or internal combustion machinery, the quantity of carbon-dioxide gas available shall be equal in volume to not less than:

(a) 40 per cent of the gross volume of the space or the larger space, including the volume of any casings that are below the height above which any horizontal area of a casing or any combined horizontal areas of the casings are 40 per cent or less of the largest horizontal area of that space; or

(b) 35 per cent of the gross volume of the space or the larger space, including the volume of the casing or casings;

whichever is the greater.

(2) The application of subregulation (1) in relation to a cargo ship of less than 2,000 tons shall be varied by substituting ‘35’ for ‘40’ (first occurring) and ‘30’ for ‘35’.

(3) In calculating, for the purposes of this regulation, the gross volume of a machinery space in a motor ship in which a main engine starting air tank is fitted, there shall be added to the volume of the space a volume equivalent to the volume of air at atmospheric pressure which may be released into the machinery space from a relief valve or a fusible plug, if any, of the main engine starting air tank.

(4) For the purposes of this regulation, where spaces containing boilers and internal combustion machinery are not separated by a bulk-head sufficient to prevent the passage of fire-smothering gas, they shall be regarded as a single space.