(160c) A Medium-Scale Field Test On Expansion Foam Application – Key Findings of LNG Pool Fire Suppression On Land

Expansion foam has been identified as one of the promising safety measures for LNG pool fire suppression. However, little is known concerning the mechanisms and effectiveness of foam in suppressing LNG fire. Thus, there is a need to perform outdoor LNG spill tests for emergency preparedness and response training in case of accidental release. In this work, a medium-scale field test observing the effects of expansion foam dispersed onto LNG pool fire was conducted on a concrete pit (6.40 m  10.06 m  1.22 m). LNG was released into the pit up to 0.20 m (8 inch) thickness and then the vapor cloud was ignited to form a pool fire. Subsequently, high expansion foam was applied to control the fire. Several parameters were measured during the LNG spill tests, such as temperatures of foam and fire, radiant heat fluxes, and fire sizes (height and area). In addition, mass burning rate was measured using thermocouples that are installed at different elevations around the concrete pit. Results showed that at the heat flux level of 5 kW/m2, the hazard distances decrease from 19.72 m to 5.49 m which is about 72 % reduction by foam application. The radiant heat flux contours around the pit were also obtained from the radiometer measurements at a certain distance from fire. In addition, it was observed that expansion foam reduces fire height around 58 %. Mass burning rate of LNG pool applied by 1.22 m foam depth was measured as 0.082 ± 0.002 kg/m2s. Based on temperature data of expansion foam during fire test, the minimum effective foam depth was determined as 0.61 m, where foam temperatures stayed below 100 oC to maintain the shape of bubbles and provide heat insulation to LNG pool. In addition, a theoretical model of expansion foam and LNG system was proposed to understand the heat transfer and the underlying mechanisms of fire control and suppression. The model suggests that expansion foam can have three layers; thin frozen layer, non-frozen layer, and foam breaking layer resulted from the evaporation of water in foam at above 100 oC. Finally, these findings can be used to validate the effectiveness of expansion foam on LNG fire control and provide design guidelines of foam system to the LNG industry. The understanding of LNG fire and its mitigation techniques will improve the fire and emergency response services and help to save lives and protect properties in the LNG industry.