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.

A series of large-scale fire tests were conducted on the extinguishment of corrugated cartons stored on metal racks. Three different storage heights (3.0 m, 4.5 m, and 6.0 m) were investigated. A specially designed water applicator, supported at a close distance from the top of the test array, was used to deliver a uniform water application density directly onto the array. The applicator could be actuated at any stage of the fire development process to simulate sprinkler response under different fire scenarios. Products of combustion from the fire were collected by a large-capacity calorimeter for the determination of heat release rate for the entire test duration. The effects of water application rate, fire size at the time of water application, and storage height were examined. A single empirical correlation of the extinguishment data was established between the fuel consumed during extinguishment normalized by the fire consumable mass left at the time of water application, Mext/Mo,w' and the wat~r~pplication rate normalized by the mass burning rate at water~pp!ication, Mw/M b w' A power law relationship exists between Mext/M o wand Mw/M b w with the pOwer being -1.55. The same kind of correlation was 'also obtained in a laboratory-scale extinguishment study on wood cribs and wood pallets of different heights. Based on the correlation, a critical water application rate (per unit exposed surface area) for rack storage array of corrugated cartons was determined to be 3.0 g/m 2s which is very close to the values reported for wood arranged in other geometries such as crib, slab, and pallet.