Fire ventilation

The stairwell is full ofcold smoke, which canbe difficult to vent out.an extinguishing operation, are in this case positive, sincethe operation can be implemented with only a limitedspread of fire gases to the stairwell. This requires, however,making an opening in the apartment on fire (outlet).To take into consideration at stairwells containingcold fire gases:• If an apartment door in the upper part of thestair well is opened by evacuating people, fire gasescan quickly spread to this apartment. The fire gaseswill, however, be cold and diluted, which meansthat people in other apartments will be lessexposed to risk. If an apartment door is openedthis will also lead to a pressure drop in thestairwell, and both the outlet through the roof ofthe stairwell and any positive pressure ventilationwill be less effective.• During the summer problems can arise if it iswarmer outside than inside the stairwell, even ifthe stairwell is filled with fire gases. It is thenconceivable that fire gases will collect in thebottom of the stairwell, especially in very highbuildings.115