Water as a fire extinguishing agent has been well known for as long as man has used fire. The knowledge about the benefits of using finely atomized water sprays is not new either. There are several examples of commercially available nozzles from the 1930’s to 1950’s and documented research from the 1950’s and 1960’s concerning such applications.
A fire protection water mist system uses very fine water droplets (mist) to control, suppress or extinguish fires byfollowing key actions:
- By cooling both the flame and surrounding heat during evaporation take place,
- By local inerting the fire source where it displacing oxygen during vaporization of the mist, the vaporization increase volume by 1640 times and the oxygen is displaced locally at the fire source.
The effectiveness of a water mist system in fire suppression depends on its spray characteristics, which include the droplet size distribution, flux density and spray dynamics, with respect to the fire scenario, such as the shielding of the fuel, fire size and ventilation conditions.
The use of water mist fire suppression, when compared to the use of gaseous agents and traditional sprinkler systems, has revealed advantages such as:
- Immediate activation
- High efficiency in the suppression of a wide variety of fires
- Minimized water damage
- Environmentally sound characteristics
- No toxic problems
The NFPA 750 defines three pressure regions for water mist-generating technologies: low, intermediate and high pressure systems where high pressure water mist shown the following advantages:
Water mist systems are unique and specifically designed for each individual protection requirements.
- Better penetration into the seat of the fire
- Superior coverage of the protected volume
- An improved cooling effect from better mixing of gases and high evaporation rate
- Lower overall system weight
- Less water consumption
Systems are designed according to the water requirements for controlling, suppressing or extinguishing the fire, and their specifications for storing the water required for extinguishing.