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Prediction Based Design of Fire Detection for Buildings With Ceiling Heights Between 9 m and 18 m.


pdf icon Prediction Based Design of Fire Detection for Buildings With Ceiling Heights Between 9 m and 18 m. (2906 K)
Davis, W. D.; Notarianni, K. A.

NISTIR 6199; 47 p. July 1998.

Sponsor:

National Aeronautics and Space Administration, Washington, DC

Available from:

National Technical Information Service
Order number: PB98-148158

Keywords:

ceiling jets; draft curtains; experiments; fire models; heat detectors; high bay; pool fires; smoke detectors; sprinkler activation

Abstract:

The analysis of hangar experiments (NIST TN 1423) with 15 m and 22 m ceiling heights has led to a better understanding of the evolution of a fire driven ceiling jet. This work has demonstrated the impact of the presence of a hot upper layer on the radial and vertical temperature profiles of the ceiling jet. The importance of using a fire size dependent radiative fraction is established which, when used in conjunction with models which account for the entrainment of upper layer gas into the plume, provides better predictive capabilities for the plume centerline temperature. Plume and ceiling jet algorithms, which model the observations, have been developed and embedded in a new zone fire model. The analysis of detector response using these experiments has resulted in the ability to establish threshold fire sizes for using smoke and heat detectors. It has also led to the recommendation of a lower temperature threshold to be used in computer models to determine smoke detector activation. Guidelines for spacing of smoke and heat detectors are discussed. The importance of a draft curtains at these heights is established, and the impact of the draft curtains on detector spacing is demonstrated.