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Some Factors Affecting the Design of a Furniture Calorimeter Hood and Exhaust.


pdf icon Some Factors Affecting the Design of a Furniture Calorimeter Hood and Exhaust. (1484 K)
Cooper, L. Y.

NISTIR 5298; 25 p. December 1993.

Journal of Fire Protection Engineering, Vol. 6, No. 3, 99-112, 1994.

Available from:

National Technical Information Service
Order number: PB94-139193

Keywords:

furniture calorimeters; exhaust systems; buoyant plumes; calorimeters; fire plumes; flame length; wall flows

Abstract:

This work considers factors affecting the design of an effective and versatile furniture calorimeter hood and exhaust system. The purpose of the furniture calorimeter, design functions, and inherent limitations of a particular design are discussed. The interactions between the hood structure and the fire and its plume are analyzed in the context of avoiding: flame impingement on the hood; enhanced combustion of a test article, over and above that of a free-burn; loss of combustion product plume gases due to "spill-over" below the hood; and unacceptable dilution of plume gases in the measurement section of the exhaust duct. The concept of the ideally designed hood is introduced, where, throughout the course of the burn of a test article the hood is always immediately above the flame tip and the exhaust rate always exactly matches the hood-ceiling-elevation plume-flow rate. Methods to partially or completely achieve the ideal design are presented. These include the combined features of adjustable hood elevation and adjustable hood exhaust rate. The ideas and results of analyses developed are applied in examples relevant to the existing furniture calorimeter hood and exhaust system of the NIST Building 205 Fire Research Laboratory. Recommendations for improvements to this facility are presented.