Water mist systems are used for special applications in which it is decided that creating a heat absorbent vapor is the primary objective. 

      This type of system is typically used where water damage may be a concern, or where water supplies are limited. NFPA 750[13] defines water mist as a water spray with a droplet size of "less than 1000 microns at the minimum operation pressure of the discharge nozzle.

       " The droplet size can be controlled by the adjusting discharge pressure through a nozzle of a fixed orifice size. By creating a mist, and equal volume of water will create a larger total surface area exposed to the fire. 

         The larger total surface area better facilitates the transfer of heat, thus allowing more water droplets to turn to steam more quickly.