CHAPTER 11

Question 0

Atmospheric conditions at high rise fires

Answer 0

• Wind blowing against a building seems to split about 2/3 of the way up the building
• Wind exerts pressure on the windward side and suction on the leeward side of the building
• A high rise building may be tall enough to penetrate the inversion layer
• Lapse will move smoke up and away from the fire
• Pause acts as a roof to rising smoke

Question 1

What is the principal smoke moving mechanism in a High Rise fire

Answer 1

Thermal energy of the fire

Question 2

Stack effect at high rise fires

Answer 2

• Stack effect may be the dominant factor affecting smoke movement in a given situation
• It is most significant in cold climates in the wintertime
• With winter stack effect, the greatest flow of air will be at the 1st floor, with the flow decreasing as the height of the building increases
• Stack effect is NOT caused by the fire

Question 3

High rise air condition facts

Answer 3

• The type of condition will determine whether or not the air conditioning is a significant factor in smoke movement
• Individual room units which draw air from the outside of the building will have no effect on the general situation
• Air condition units which draw air from the corridor will cause polluted air to be drawn into the rooms