oxygen displacement and radiation attenuation are the three extinguishing mechanisms of the WMFSS. As in most cases, these three mechanisms have a dominant effect on control,suppression and extinguishment of the fire. The vapor/air dilution and kinetic effect supplement the main mechanisms to help extinguish the fire [4]. The terminal velocity of the water drops from the WMFSS is not large enough to reach the seat of the fire; it is assumed that they could evaporate completely without wetting the fire source. Therefore, the WMFSS could be used to extinguish liquid fires without explosion [8].