Wood Crib Fires under High Temperature Low Oxygen Conditions

Abstract

wood crib fires were investigated in a compartment fire under post-flashover conditions using a natural gas (NG) burner to rapidly generate 500 o C furnace temperature and oxygen levels of 12%. The subsequent fire temperatures were 600-700 o C, with oxygen levels below 5%. These conditions reproduce the circumstances in developed, under-ventilated fires inside a hot compartment where yet uninvolved material is available for combustion. Two pine crib fires were investigated: a 3 kg crib which resulted in lean overall combustion and a 9 kg crib that resulted in rich overall combustion. For the low fire load lean combustion case, the combustion efficiency was high and the yield of toxic products was low. However, for the high fire load with rich combustion the wood was mainly gasified and the combustion efficiency was very low. An extreme fire toxicity condition, as well as the circumstances for back- draft explosions, was generated in this post-flashover rich combustion case.