Water Mist System

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 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, an 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. A water mist, which absorbs more heat than water per unit time, due to exposed surface area, will more effectively cool the room, thus reducing the temperature of the flame.