- Author
-
Klote, J. H.
- Title
- Considerations of Stack Effect in Building Fires.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Sponsor
- U.S. Fire Administration, Emmitsburg, MD
- Report
-
NISTIR 89-4035
May 1989
92 p.
- Distribution
- Available from National Technical Information Service
- Keywords
-
stack effect
|
building fires
|
elevators (lifts)
|
smoke vents
|
smoke transport
|
stairwells
|
wind effects
|
elevator shafts
- Abstract
- The following driving forces of smoke movement in buildings are discussed: stack effect, buoyancy of combustion gases, expansion of combustion gases, wind effect, and elevator piston effect. Based on an analysis of elevator piston effect, it is concluded that the likelihood of smoke being pulled into an elevator shaft due to elevator car motion is greater for single car shafts than for multiple car shafts. Methods of evaluating the location of the neutral plane are presented. It is shown that the neutral plane between a vented shaft and the outside is llocated between the neutral plane height for an unvented shaft and the vent elevation. Calcultions are presented that show that pressure losses due to friction are generally negligible for unvented shafts with all doors closed. The capabilities and limitations of network models and zone models are discussed. The network method was applied to several cases of open and closed doors and shaft vents likely to occur during firefighting. For the cases evaluated, shaft venting did not result in any significant reduction in smoke concentrations on the floors of the building. One of the cases showed that for low outside temperatures, bottom venting of a shaft can result in shaft pressurization. Other cases demonstrated that elevated temperatures of combustion gases can result in downward smoke flow from one floor to another. Much of the information in this paper is applicable to the migration of other airborne matter such as hazardous gases and bacteriological or radioactive matter.