Experimental Study on Water Mist Suppression of Poly(Methyl Methacrylate) PMMA Fires

Suppression of Poly(methyl methacrylate) PMMA fires by water mist will be studied in this paper. A simple test is developed to study the critical water flow rate under different radiant heat flux. The test is found to be suitable for studying the extinguishment effects of fine water droplets involving oxygen displacement, gas phase and fuel surface cooling. Water mist is generated by a single pressure nozzle, with the water mist characteristics measured by the Laser Doppler Velocimetry or the Adaptive Phase Doppler Velocimetry System (LDV/APV system). The interaction between water mist and the PMMA flame will be studied in a confined space with ventilation control in a cone calorimeter. The heat release rate, oxygen, carbon dioxide and carbon monoxide concentrations, and other important parameters of the interaction under various conditions are measured. It is found that discharging adequate amount of water mist would suppress the diffusion flame in the confined space. Reignition might occur once water mist stopped discharging to the fuel surface. Higher heat release rate and more smoke and toxic gases were produced than from those in first ignition.