Clear-cut response

Published:  16 November, 2011

Compartment fires present a range of risks to the firefighter. The dangers of the combustion gases, radiant heat and explosions are but some of the deadly hazards faced by responders. Nowhere is this more apparent than onboard a ship, and in particular on a Corvette, as built for the Swedish Navy for surface to surface warfare, mine countermeasures (MCM) and anti-submarine warfare (ASW). Ann-Marie Knegt reports on a versatile extinguishing system that is enhancing safety and fire response for Sweden’s Navy.

Compartment fires present a range of risks to the firefighter. The dangers of the combustion gases, radiant heat and explosions are but some of the deadly hazards faced by responders. Nowhere is this more apparent than onboard a ship, and in particular on a Corvette, as built for the Swedish Navy for surface to surface warfare, mine countermeasures (MCM) and anti-submarine warfare (ASW).

Robert Averin, a Project Engineer at the Naval Warfare Procurement Office at the Swedish Defence Materiel Administration (FMV) was working with his colleague Pontus Nordberg in 2001. Pontus had conducted tests with a new concept called the coldcut cobra (CCC) extinguishing system to see if this could be used to extricate pilots from crashed JAS Aircraft. After extensive trials it was concluded that the system wasn’t suitable for this particular purpose. However it sparked interest for a different goal.

The cutting extinguishing method works by ejecting a mixture of water and a cutting agent through a special lance nozzle at high pressure – 250 bar upwards. This creates a jet of micro droplets that can cut through all known building materials.

Firefighters can determine the right location to penetrate a compartment or read the building by using a thermal imaging camera from the exterior,explains Anders Trewe, Key account Manager for Navy and Shipping for Cold Cut Systems (CCS), based in Sweden: “The opening only measures a couple of millimetres to let the water jet through the door or the framework. The system leaves such a small hole that no oxygen will enter the room. The micro droplets that are released into the room ensure that a highly effective extinguishing reaction is set in motion, as the water evaporates and cools the fire gases as well as potential fire pockets; inerting the fire gas mixture in the room.” Although the coldcut cobra extinguisher can be used with foam for extreme situations, the manufacturer states it will be equally efficient without, as its extinguishing capabilities are effective while maintaining its completely green credentials (the CCS holds an ISO 14001 approval alongside ISO 9001). The water mist leaves no residue and no harmful substances during the firefighting operation.

“The coldcut cobra extinguisher is faster, safer and more efficient. It also performs well outside compartments, and in a normal living room of about 30m2 for instance, it enables firefighters to put a fire out within a minute. You will typically lower the temperature from a developed fire at a temperature of 600 degrees oC, down to a 100 degrees oC in less than a minute, using about 50 litres of water,” explains Anders Trewe.

Cold Cut Systems demonstrated the CCC to Robert Averin in 2001, when he was also presented with a report from Lund University in Sweden (2001-02-07, Cutting extinguisher, testing in ship environment). He explains that this really opened his eyes to the possibilities for the system as a tool for naval firefighting operations onboard ships. “Finally there is a method that creates a safe environment for ‘smoke divers’ (ie firefighting personnel that enter a compartment fire), and which enables them to safely open up a space onboard without having to enter a compartment. This system eliminates the concerns for a flashover or backdraught as soon as oxygen is added to a confined space.”

The decision was made to acquire the system when the Swedish Navy’s Ship Inspection Department set the requirement that an alternative had to be found to the fixed extinguishing systems in the engine rooms, in case they failed.

The Swedish Navy conducted a series of extensive tests and trials at both the Maritime Naval Training institute and at the National Institute in Borås run by SP Research Institute (2002-07-03, SP-report 202346). The tests revealed that the system worked as well as Cold Cut Systems claimed.

Ola Håkansson, an Engineer at HMS Helsingborg (Visby Stealth Corvette), was also heavily involved in purchasing and testing the coldcut cobra. “Our tests have showed that the cutting extinguisher is a great tool, and even if it does not extinguish the fire completely, combustion gases have at least cooled down so much that the environment is safe enough for the smoke divers to finish the job.”

Because the Corvettes “Stockholm” and “Malmo” were to be part of the international response force in the Gulf of Aden in 2009, the acquisition process was sped up, and in less than three months there were two fully functioning, maritime converted, coldcut extinguishers onboard the ships in Djibouti.

“We now have five dual built in units for our new Visby Class Corvettes, two stand-alone systems for our Stockholm Class Corvettes and two stand-alone units for our Gothenburg Class Corvettes. We are using the cutting extinguishers as a portable extinguishing system that is fixed at strategic location on the wall. This enables us to attack the fire from multiple positions so we can achieve the best extinguishing effect,” said Ola.

Since the cutting extinguishing method turns around the mindset of traditional firefighting, the training and integration of the method within an organisation is an issue. New technology is not new phenomena to the Swedish Navy, as the cutting extinguisher method is fully integrated in standard training procedures, including e-learning and full size training facilities at their Sea Safety School in Karlskrona. The training time is less than eight hours after which personnel are fully trained in using the cutting extinguisher on board ships.

As part of the integration, onboard all vessels the compartments have been marked with a number of points that show where it is best to cut through the hull without damaging electric and hydraulic equipment and wiring. Obviously a war ship is filled with sensitive electronics, but the coldcut cobra system should not damage this, whereas conventional firefighting operations could cause water damage. High-pressure water mist does not affect electrics due to the miniscule droplet size.

Anders Trewe adds that the C330H naval kit has been specifically engineered in non-magnetic stainless steel, in high IP classification, as well as being suited for straight integration with the vessels’ existing hydraulic system. It is delivered with an interface at the hydraulic motor – assembled on the hydraulic pump – and includes all main components including the hand lance.

CCS manufactures a range of coldcut cobras for different firefighting applications for use in compartments as well as ventilated areas, and the system is currently being trialed and operated by multiple fire services all over the world, including: Sweden, Norway, Denmark, The Netherlands, UK, Germany, Finland, Czech Republic, Poland, Denmark and Malaysia.

  • Operation Florian

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