Study on the suppression mechanism of water mist on poly(methyl methacrylate) and poly(vinyl chloride) flames

摘要

In this study, the action of water mists on poly(methyl methacrylate) (PMMA) and poly(vinyl chloride) (PVC) in a confined space under different external radiant heat fluxes was studied. Water mist was generated by a downward-directed single pressure nozzle. Physical characteristics of the water mist were measured by laser doppler velocimetry and the adaptive phase doppler velocimetry system. The heat release rate, oxygen, carbon dioxide, and carbon monoxide concentrations, and other important parameters of the interaction under various experimental conditions were measured with cone calorimeter. To explain experimental results, the chemical suppression mechanisms of water mist extinguishing PMMA and PVC flames are investigated from literatures, and the corresponding proposed chemical reactions with water mist are presented. The investigation shows that aromatic compounds are formed by light hydrocarbon products with water mist for PMMA flame. Otherwise, for PVC flame, the decrease of temperature with water mist prevents aromatic compounds from oxidation and degradation.