Water is converted into mist at high speed at 120 bar. The heat of evaporation of water is fairly high.
Evaporation occurs on the surface of the water droplets. The total surface area of droplets increases as their diameter decreases.
That means that small droplets are able to absorb much more heat than large droplets over a given period of time.
The greater the pressure in the sprinkler heads, the smaller the diameter of the water droplets in the mist.
During evaporation, the water volume expands by a factor of 1640. This volume expansion in the heart of the fire drives the oxygen away, which decreases combustion.
The rapid reduction in temperature protects the space and any people present from the heat radiation.
The system is based on a high pressure water mist system in accordance with the applicable regulations. The pressure in the sprinkler heads (at least 60 bar) creates what NFPA 750 describes as ‘finest water mist’. This generates water droplets with a diameter of less than 10 micrometres (one metre under the sprinkler head), which results in very fast evaporation and heat absorption, as well as extinguishing the fire.