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Cobra efficiency confirmed by new research

 

Scientific spray characterization of the cutting extinguisher

Research done by, SP Technical Research Institute of Sweden, sponsored by VINNOVA. 

This study presents the first experimental measurement of the droplet diameters from a cutting extinguisher, the coldcut™ cobra. The results show that the spray from a cutting extinguisher is characterized by very small droplets. These measurements confirm earlier explanations of the very high efficiency of the cutting extinguisher, and in addition lead to more detailed understanding of its extinguishing and suppressing effect.

Due to the very rapid cooling, inerting and radiation absorption, fire suppression is much more effective with these micro droplet diameters compared to systems with larger droplets such as fog nozzles and fog spears connected to an enhanced low pressure system (i.e. 40 bar @ pump).

The droplet sizes for coldcut™ cobra systems are significantly smaller compared to the other systems employed in this study. The significance of this is that the smaller water droplets from the cutting extinguisher heat up and evaporate at a much faster rate and extract more energy from the fire than the conventional systems studied. This in turn leads to a superior speed of evaporation (i.e. temperature reduction), which also results in increased inerting effects.

 

The volumetric absorption efficiency is around 5 times higher for the cutting extinguisher compared to the conventional systems studied!

The cutting extinguisher also produces very high droplet velocities, i.e. 7 m/s at 10 meters from the nozzle, while the comparison systems show velocities around and below 1 m/s within 1-4 meters from the nozzles. Hence, the high velocity of the cutting extinguisher creates a high momentum spray that projects the water mist long distances into a fire compartment, making it possible to act on fires at a long distance from the nozzle, several times farther away than the compared systems. The high momentum provides more effective means of entraining the hot fire gases with the water mist, improving cooling efficiency.

The fact that micro droplets produced by water mist from a cutting extinguisher are more prone to follow the air flow than falling to ground means that exposure time available for the suppression mechanism to act on the fire is much longer. This is also of significant importance when combining the coldcut™ cobra with Positive Pressure Ventilation (PPV).  

 Scientific spray characterization of the cutting extinguisher.pdf

For any questions, please contact;

Torwald Snickars >>, +46 738 004200

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