Heat Flux Pipe In Large-scale Fire Tests

Abstract

This paper presents the results from a series of commodity classification tests conducted with a unique flame heat flux instrument, i.e., Heat Flux Pipe. In the early 1990's, FM Global established the ranking of combustible products with a commodity classification test using benchmark commodities. The methodology used heat release rate calorimetry to determine the hazard level of a commodity. It is well known that flame heat flux is closely linked to flame spread and heat release rates associated with various commodities. In the present test series, the initial sprinklered tests were conducted with Class II and Standard Plastic commodities and a distinct difference in maximum flame heat flux was measured, i.e., 114 kW/m 2 and 192 kW/m 2 respectively. Subsequent freeburn commodity classification tests with Class II, wood pallet and Standard Plastic showed large measured maximum flame heat fluxes, 140 kW/m 2 , 190 kW/m 2 and 440 kW/m 2 respectively. This difference in flame heat flux between commodities can be exploited to better quantify the commodity hazards and hence the corresponding protection requirements. Also, the Heat Flux Pipe has been shown to be a robust instrument in large fires, up to 30 MW, and withstanding flame heat flux level of up to 440 kW/m 2 . The Heat Flux Pipe can clearly be used in other fire scenario where flame heat flux measurements are desirable.

Interaction between Crosswind and Aviation-Fuel Fire Engulfing a Full-Scale Composite-Type Aircraft: A Numerical Study

“…Figure 16a), the mean heat flux is considerably higher with a magnitude of 200 kW/m 2 on the windward side of the fuselage due to an impingement of the buoyant plume on the fuselage surface. The peak in heat flux is a factor of four increase relative to quiescent fires, and this trend is in agreement with the measured one for large fire [5,6,33]. The substantial thermal radiation develops also on the leeward side of the fuselage when it is immersed in a fire, resulting in a circumferential variation in the heat flux distribution.…”

Assessment of Commodity Classification for Sprinkler Protection Using Representative Fuels

“…In contrast to the 2×2×2 fuel array used in previous work [1,2], a 2×4 and 3-tier high fuel array is used in the present study. A schematic of the test setup is shown in Fig.…”

“…In addition, Wu [2] attempted to develop a new commodity classification method by the use of flame heat flux measurements. However, the cost of full-scale sprinkler tests is high and only limited full-scale data for standard commodities are available for comparison; the empirical correlations used by Chicarello and Troup [1] can be hardly extrapolated to new commodities; and the measured flame heat fluxes by Wu [2] showed no correlations with the fire hazards of well known commodities. Consequently, it remains questionable how to evaluate the fire hazards of commodities and whether existing classes can be regrouped or simplified.…”

Flammability characteristics at applied heat flux levels up to 200 kW/m2

“…The agreement provides support for the accuracy of higher heat fluxes achievable by the AFM, given that the same calibration procedures were used for the entire applied heat flux range. Understanding of the material behaviour at higher applied heat flux than commonly tested is important because there are practical applications in the real world where the heat flux from fires can reach 200 kW/m 2 or beyond [10][11][12]. Note the unexpected non-linear trend starting around 60 kW/m 2 .…”