Fire ventilation

elatively cold and diluted. Because of the size of the roomthe fire will be fuel controlled for a long period, and maynot become ventilation controlled at all.The risks associated with fire ventilation are very smallin this situation.It is also conceivable that a similar situation will occur inthe case of apartment fires. The interior ceiling and wallsmay be incombustible (e.g. plasterboard) and if the interiorfurnishings (furniture etc.) are placed in such way that afire in an individual object does not spread to other objects,the fire can remain fuel controlled during the entire firescenario. It may self-extinguish when the fuel is used up.The risks associated with fire ventilation in these situationsare also very small.Small fires can, however, develop quickly and powerfullyduring fire ventilation if they are located in double flooring,ceilings, under floor areas, or confined in other waysin what is otherwise a large room. This sets extensive tacticalrequirements, above all in the form of the build-up ofresources. Even if the room is well ventilated there can beconcealed areas that are poorly ventilated.Since the fire gases has a relatively low temperature and verylimited buoyancy force, an opening for an outlet should bemade as high up as possible, preferably in the roof. Supply airshould be taken from the lowest possible point, and mechanicalventilation should be carried out. Negative pressure ventilationcan as a result of practical problems be difficult to implement,especially if the room is very large. It may also be difficultA small fire in a largeroom causes the smoketo have a low temperatureand therefore itcan be difficult to vent,both with andwithout fans.106