Small Scale Experimental Study on Backdraft

Seven small scale experiments were carried out to research the critical threshold value for backdraft to occur. Backdraft experiment platform with 0.9 m length, 1.2 m width and 0.6 m height was built, based on the platform, wood cribs which was 0.3 m length, 0.3 m width and 0.3 m height, was used as fuel. Data of temperature, oxygen concentration, combustible gases concentration within the compartment were collected, IR camera was used to record the size and temperature of fireballs. Results show that the minimum concentration of combustible gases for backdraft to occur is about 11.6 percent vol in the seven tests, and carbon monoxide and hydrogen play very important parts, Sizes of fireballs are proportional to the concentration of combustible gases, more powerful fireballs can be observed when the concentration of combustible gases is greater, temperature of fireballs is more than 180 Celsius degree. The critical threshold value of backdraft are crucial indicators for backdraft, lives of fire fighters can be saved with better understanding of backdraft and equipment.