Suppression Of Rack-storage Fires By Water

Abstract

A s e r i e s of large-scale f i r e suppression t e s t s was conducted for two d i f f e re n t commodities stored in s t e e l racks of d i f f e r e n t heights, and were analyzed using a global heat balance model. In these t e s t s , water was applied uniformly on top of the storage array a t selected f i r e s i z e s t o determine the f i r e s u p p r e s s i b i l i t y f o r a commodity a t a given storage height. A f i r e suppression parameter was used t o correlate the f i r e suppression r e s u l t s of these t e s t s . The f i r e suppression parameter is a function of fuel d e n s i t y , f u e l s p e c i f i c heat, ignition temperature, heat of combustion, burning r a t e , heat of pyrolysis, and water application r a t e . The data indicate t h a t the combustible packaging and overall storage arrangement have s i g n i f i c a n t impact on the magnitude of the c r i t i c a l water density f o r f i r e suppression. KEYWORDS: water-based f i r e suppression.

Reduced-scale Experiments On The Water Suppression Of A Rack-storage Commodity Fire For Calibration Of A Cfd Fire Model

“…The mass of the constituents of one (conditioned) box procured from UL is shown in Table 1 including the combined standard uncertainty, which is dominated by instrument reading accuracy. The mass of the constituents of the Group A Commodity reported by Yu et al [1] differs by as much as 20 %. Although the mass of plastic cups is twice that of the cardboard, the early fire behavior is dominated by the burning of the corrugated paper.…”

“…Several nozzle sizes were used, depending on the desired water flux. Table 2 [1] found that water suppression was achieved with an average flux of 0.08 kg/m 2 -s in a two tier fire. The propane line igniters were composed of two parallel 30 cm long and 12.5 mm diameter copper tubes.…”

“…Pan measurements demonstrated that the applied density was approximately uniform. In the experiments, the water nozzles were positioned close to the commodity, not unlike the FM Required Delivered Density (RDD) tests [1]. It is thereby assumed that the plume had little effect on the droplet trajectory.…”

“…empirical parameter related to the suppression, which accounts for the fuel density, fuel specific heat, ignition temperature, heat of combustion, total burning rate, heat of pyrolysis, and average water application rate. Yu et al [1] showed that the coefficient k can be correlated as a linear function of the water application rate for the period 240 s after the time of water application. The value of k was different for the two types of commodities tested.…”

“…FDS solves numerically the conservation equations of mass, momentum and energy that govern lowspeed, thermally-driven flows with an emphasis on heat transfer associated with fire. This work focuses on application of the model to simulate the burning and suppression of a rack-storage commodity fire, a topic that has been the focus of previous research [1][2][3].…”