The Merchant Shipping (Fire Protection: Large Ships) Regulations 1998

19.—(1) In every ship of Class VII of 500 tons or over there shall be provided in each closed ro-ro cargo space and each cargo space intended for the carriage of motor vehicles with fuel in their tanks for their own propulsion an effective power-ventilation system to provide at least six air changes per hour based on an empty hold. Ventilation fans shall where practicable be run continuously whenever vehicles are on board. Where this is impracticable, they shall be operated for a limited period daily as weather permits and in any case for a reasonable period prior to discharge, after which period such spaces shall be proved gas-free. One or more portable combustible gas detecting instruments shall be carried for this purpose. The system shall be entirely separate from other ventilating systems. Ventilation ducts serving such spaces capable of being effectively sealed shall be separated for each cargo space. The Secretary of State may require the capability to increase the number of air changes when vehiclesare being loaded or unloaded. The system shall be capable of being controlled from a position outside such spaces. In addition—

(a) the ventilation shall be so arranged as to prevent air stratification and the formation of air pockets;

(b) means shall be provided to indicate any loss of the required ventilating capacity on the navigating bridge;

(c) arrangements shall be provided to permit a rapid shut-down and effective closure of the ventilating system in case of fire, taking into account the weather and sea conditions.