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 40 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. Water mist prevents re-ignition, requires less water, reliable and versatile.
AFT systems operate at a low working pressure 7.5-8.5 bar, without the AFT patented technology we would have to use approx.100 bar to achieve the same effects.
The water mist created by the AFT system help extinguish fires rapidly due the dual effect of cooling and blanketing.
Water mist removes two of three elements of the fire triangle heat & oxygen
Cooling Effect: The optimal droplets created by AFT water mist systems, increase surface area to maximize the efficient absorption of heat.
Oxygen Displacement: The droplets evaporate rapidly and expand to displace oxygen in the proximity of the fire.
Radiant Heat Attenuation: The droplets provide effective protection from radiant heat, Energy is taken away from the fire, due to the AFT cooling effect.
Water mist prevents re-ignition, requires less water, reliable and versatile