AFT has applied advanced aerodynamics technology from flow engineering applications involving liquid/gas mixtures to create AFT water mist firefighting systems. The AFT technology creates a narrow distribution of ultra fine water mist, foam or CAFS using speciality nozzles.
The droplets create an enlarged surface area (almost 50 times) as compared to a conventional water tender. This results in rapid cooling due to extensive heat absoption and the resultant steam generated expands 1640 times in volume thus inserting the atmosphere around the fire. The combined effect of cooling and blanketing results in effective rapid extinguishing.
NFPA 750 defines water mist as “a water spray with for which the Dv0.99, for the flow-weighted cumulative volumetric distribution of water droplets is less than 1000 microns at the minimum design operating pressure of the water mist nozzle”.
Current water mist systems today deliver anywhere between 50-999µm. Based on pressure used to create droplets, the classification of water mist is as below.
- Low pressure: Systems which operate with pressures less than or equal to 12 bar
- Medium pressure: Systems operating between 12-34.5 bars
- High pressure: Systems which use pressure greater than 34.5 bar
- AFT’s firefighting nozzles deliver the optimum droplet size of 150 microns and therefore outperform any other comparable product.
- Many companies assert having low-pressure fire extinguishers. AFT’s portable devices demonstrate it with a working pressure of less than 10 bars!
The chart compares the speed of cooling between a 5 mm droplet to various droplets of water mist. As we can see, the AFT droplet size of 150µm cools 40 times faster than a 5mm droplet.
Using the atomization technology, the water mist is developed by using the kinetic energy of compressed air and mixed with the liquid in specially designed multiple nozzle systems. Atomisation works with compressed air to pressurise the system, propell the liquid and mix it with the liquid for creating mist.
Atomisation creates water mist in the range between 100-150 µm which results in 40 times more cooling as compared to conventional water spray of diameter 5000 µm.