Improving fire suppression of water mist by chemical additives

Although water mist fire suppression system (WMFSS) is very common, there are concerns that the system is not efficient in controlling some fires. Additives are proposed to use in a WMFSS for better fire protection. In this paper, different groups of additives for WMFSS will be briefly reviewed. Experimental studies on the surface physical and chemical characteristic of polymethylmethacrylate (PMMA) under four groups of original polymer surface without treatment, self-extinguishment, suppressed by water mist and by water mist with sodium chloride NaCl, are reviewed. The surface profiles, element constitutions, binding energies and functional groups of PMMA surfaces were analyzed with scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectrometer (FTIR). The near surface molten polymer and bubble layers in burning polymethylmethacrylate (PMMA) are found to be very complicated. The melted surface of burning PMMA is not saturated with pure MMA. Results also demonstrated that chemical reactions do occur while applying water mist. Water mist with NaCl can penetrate deeper on the burning surface of PMMA, suggesting that NaCl might be involved in the extinguishment reactions. The chloride ion from NaCl might be responsible for the interaction with the melting surface of PMMA.