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SCIENTIFIC RESEARCHES

SCIENTIFIC RESEARCHES. MSB report (ENG) – Practical & operational use of cobra Dielectric test of cutting extinguisher, SP (ENG) J Gsell (ENG) – Fire suppression capabilities of water mist GMFRS – Steaming effects on human being

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SCIENTIFIC RESEARCHES

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  1. SCIENTIFIC RESEARCHES • MSB report (ENG) – Practical & operational use of cobra • Dielectric test of cutting extinguisher, SP (ENG) • J Gsell (ENG) – Fire suppression capabilities of water mist • GMFRS – Steaming effects on human being • The cobra project (Swe) – Method development to create safe & efficient interventions • Spray characterization of the cutting extinguisher, SP

  2. Cutting extinguishing concept –practical & operational use • MSB & SP have conducted scientific studies based on almost 10 years usage of cobra and hundreds of interventions. Findings; • cobra efficiently cool fire gases and stop fires and inerts fire gases also when temperature is low • cobra enables quicker start of action • Tactical choices have been increased when combining cobra, thermal camera and PPV • High quality education and training enhances the usage and advantages of cobra • Damage to property and negative consequences for environment decreased significantly with the cobra-concept • Usage of cobra has improved health and safety aspects for fire fighters • Some interventions are described, also multiple use of cobras

  3. DIELECTRICAL TEST

  4. FIRE SUPPRESSION CAPABILITY • Master thesis by Julien Gsell, University of Ulster • Number of burning tests - inerting effects also when compartment was ventilated • Droplet diameter 0,1 mm has a lifetime of 0,2 sec @ 400 degrees C and fall 30 mm before being vaporized. A droplet with diameter 1 mm and corresponding values give a lifetime of 230 sec and falling distance of 680 m! • Mie-theory said increased atomization to 0,001-0,01 mm gives higher volumetric absorption efficiency • S

  5. GMFRS / FPA • Extensive testing done to establish if there will be any steaming effect of vaporized water • Totally 20 burnings • Conclusion; increased survivability when cobra is used! • (Report is not public yet) Steaming effect is sometimes an open issue, so information from GMFRS is valuable.

  6. THE cobra PROJECT • A two years project with following participating organization • Södertörn FRS • FRS SYD • Staffanstorp & Lomma FRS • MSB & Health and Safety Executive • Cold Cut Systems • A purpose was to develop tactics, methods and to exchange experience between the organizations. • Is it possible to perform interventions in a safer way by using cobra? • Will usage of cobra increase the efficiency to quickly interrupt the fire?

  7. Efficient fire fighting

  8. ALL INTERVENTIONS

  9. Diversityof usage

  10. THE cobra PROJECT • Some conclusions from the project: • The cobra cools fire gases in an very effective way • Usage of PPV facilitates when cobra is used as you can control fire gases before you start to ventilate • With a cobra you can also reach hidden fires which are normally very difficult to tackle • cobra improve safety fire fighters • Water damages and contaminated water were significantly reduced • cobra were used, with very good result, in a diversity of different type of fires

  11. SPRAY CHARACTERIZATION • A project done by SP and Cold Cut Systems • Spray from cobra is characterized by very small droplets! Cooling, interting and radiation absorption becomes more effective with these small droplets compared to system with larger droplets. • Compared systems Attack and Diffuser fog spears and Fog nozzles connected to enhanced low pressure systems (i.e. 40 bar at pump) • Brief spray theory (atomization) D ≈ We crit≈ 20 ∙ 73 ∙ 10-3 ≈ 25 micron pair * v2 1.2 ∙ 2202 • 100 bars pressure gives approx 2,5 times larger droplets

  12. Drop size distribution • Drop size distribution

  13. Efficient fire fighting • The cobra produces a very narrow distribution of extremely fine droplets. • 5 times higher energy absorption rate than other water misting systems! • Large drops means that extinguishing efficiency is dramatically reduced and water/environmental damages rapidly increases.

  14. Efficient fire fighting • cobra distance d10= 70 micron 10 m -> 7 m/s d32= 170 micron 15 m -> 5 m/s • Attack fog spear distance d10=160 micron 4m -> 1 m/s d32= 900 micron Off center & additive even smaller droplets d10 arithmetic, the average of all diameters d32Sauter mean, the ratio of volume to surface area for the entire spray

  15. Efficient fire fighting • The high pressure, resulting in a high speed and high flow, creates a high momentum spray that pushes the water mist long distances into an enclosure fire, making it possible to act on fires distant from lance despite the small droplets • This also have additional benefit in certain circumstances of entraining vitiated/contaminated air into the fire by the turbulence created • High speed gives large exchange of heat

  16. www.coldcutsystems.com

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