Full-scale fire experiments in an underground mine

Few full-scale fire experiments have been performed in underground mines, therefore the information needed to validate calculations and estimations in preventive work, risk mitigation as well as incident planning is not readily available. This paper presents two full-scale fire experiments involving a loader and a drilling rig in a mine drift in Sweden. The heat release rate in the fire experiments was determined through oxygen calorimetry, i.e. by measuring the mass flow rate, gas concentrations and temperatures at certain heights at the far end of the mine drift, downstream of the fire source. The resulting heat release rate curve of the loader fire displays a fire that is initially dominated by a sudden increase in heat release rate when the first tire is engulfed by flames and then by the slowly declining heat release rates of the large tires of the vehicle. The calculated peak heat release rate of the loader was 15.9 MW and occurred approximately 11 minutes after ignition. The resulting heat release rate curve of the drilling rig displays a fire with high heat release rates and is relatively short lived -compared with the fire in the loader. Practically all the combustible items were ignited in the early phases of the fire. The calculated peak heat release rate of the drilling rig was 29.4 MW and occurred approximately 21 minutes after ignition. The fuel load of the loader consisted mainly of the tires, the hydraulic oil and the diesel fuel. The fuel load of the drilling rig consisted mainly of the hydraulic oil and the hydraulic hoses. The heat release rate curves were validated by comparing the summed up energy contents of the participating components with the integrated heat release rate curves.