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THE HONG KONG GOVERNMENT GAZETTE, JANUARY 31, 1941.
(g) The ventilation required by these Instructions is to be provided irrespective of side scuttles, doors, hatchways, sky- lights and other apertures not built solely for ventilation.
(2) Natural Ventilation.-(a) Where the ventilation of between decks, bridge spaces and other compartments of a similar character intended for the accommodation of unberth- ed passengers is by means of cowls, the system is to be at least in accordance with the following instructions.
(b) Each compartment is to be provided with cowl ven- tilators having an aggregate area of not less than 5 square inches for each adult accommodated therein, that is 24 square inches as inlet and an equal amount as outlet.
If the compartment is abreast the machinery or boiler casings or immediately above the machinery spaces, the area of the ventilators serving the compartment must be increased by at least 33 per cent.
(c) Cowls are to be placed in unobstructed positions above the weather deck where they can
remain open in ordinary weather and must be capable of being trimmed in any direction.
*Ventilator coamings should project to the bottom of the beams of the compartment they serve. Supply ventilators are not to be placed in way of doorways or stairways or in other positions which may be prejudicial to their effectiveness.
(d) Cowl ventilator coamings must not exceed 452 square inches in area (24 inches in diameter) unless they com- municate with two or more compartments, in which case the area of the trunk leading to any one of the compartments so ventilated must not exceed 452 square inches.
Coamings must be not less than 78.5 square inches in area (10 inches in diameter).
(e) Ventilators are to be measured at the narrowest part of the air passages and the area of the cowl is to be at least 50 per cent. greater than that of the coaming.
(f) Where an odd number of ventilators is adopted the required inlet and outlet area must be maintained.
(g) Where less than four ventilators are fitted to one compartment, suitable trunks are to be provided to ensure proper distribution of air except in cases where ventilators do not exceed 15 inches in diameter when such trunking need not, as a rule, be required. Pronounced bends in the air passages are to be compensated for by additional ventilator area to the approval of the Principal Surveyor of Ships.
(3) Mechanical Ventilation.-(u) In cases where the pas- senger compartments referred to in sub-paragraph (2) (a) are ventilated by mechanical means, the arrangements adopted must be not less efficient than those described for the cowl system.
(b) Provision is to be made, either by interconnecting the air ducts from two or more fans, or by additional independent means of ventilation or otherwise, to secure a sufficient supply of air in the event of a breakdown of any part of the mechanical system.
(c) In all cases vitiated air must exhaust direct to the open air.