Fire Safety Science Digital Archive

Experimental investigations were performed to assess the effects of different obstacle obstructions in a partially confined rig, 235 mm in height, with a 1000 ? 950 mm² cross section and with large top-venting of area 1000 ? 320 mm². Three different single and multiple obstacles with cylindrical, triangular and square cross sections covering blockage ratios ranging from 5 to 30 % were used. High speed video was used to record the flame paths and lengths. These were correlated with pressure measurements. The square obstructions with the lowest volume yielded the lowest overpressures while the highest overpressures were obtained with the cylindrical obstructions. The explosion pressure was found to decrease with increasing blockage ratio and with the single obstacles rather than the multiple ones due to the formation of lower volumes of unreacted mixture