The need to preserve watertight integrity, and also to meet the threat of attack by atomic, biological or chemical warfare, has led to the development of the section system of ventilation.
Imfuneko yokugcina ukulunga kwendawo engangeni manzikunye nokudibana noloyiko lokuhlaselwa yimfazwe ye-athom,yebhayoloji okanye yamachiza,ikhokelele kuphuhliso lesixokelelwano secandelo lokukhupha nokungenisa umoya.