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New report: Efficient, low-exposure and environmentally friendly extinguishing of fires in small building units

The report «Efficient, low-exposure and environmentally friendly extinguishing of fires in small building units» has been published. The main objective is to increase the knowledge on how to extinguish fires in smaller building units efficiently in terms of time and water amount, with minimal exposure of the fire service to smoke, heat and direct contact with soot, as well as minimal environmental exposure in case of extinguishing water run-off.
In total seven medium-scale fire tests were carried out in a 13.5 square meter compartment. The fuel in the experiments co nsisted mainly of a sofa with mattresses and walls clad with OSB boards. The study focuses on indirect extinguishing (i.e., cooling of the fire gases) with four different extinguishing methods, which are:
•       Coldcut cobra cutting extinguisher and water,
•       Spray nozzle and water,
•       Spray nozzle and foam,
•       Fognail extinguishing spear and water.

In the experiments, all extinguishing methods caused the temperature in the smoke layer to drop below 150°C within 2.5 minutes and the flaming fire was extinguished. The fire re-ignited in all experiments approx. 6 minutes after the start of the experiment, except for the experiment F4 with foam where there was re-ignition after approx. 4 minutes. The experiments showed that the cutting extinguisher and extinguishing spear have a good effect, even under "artificial" limitations in the experiments (duration and direction of the extinguishment). Both of these extinguishing methods used approximately the same amount of water. As the purchase costs for a extinguishing spear are significantly less than for a cutting extinguisher, the extinguishing spear has been found to be not only an efficient extinguishing method but also beneficial from a cost/benefit perspective.

To use an external extinguishing method (cutting extinguisher or Fognail) as an immediate measure in advance of internal firefighting gives the following advantages compared with smoke diving without the use of an external extinguishing method:
•       less soot and less explosive/toxic fire gases in the fire compartment,
•       better effect of the secondary internal extinguishing agent,
•       faster reduction of the temperature in the fire compartment,
•       less sauna effect (high humidity can cause heat to penetrate the clothes of the firefighters, which in turn can lead to injuries and that the smoke divers must retreat).

The measurements during the experiments show that the use of cutting extinguishers or extinguishing spears can reduce exposure to the fire brigade with regard to heat and contact with particles.

The study was presented at “DiBK fagdag om brann 2021". The presentation (video recording and pdf) is available here:

Full report in Norwegian with English summary: (pdf