A new fire safety study by global survival technology company Survitec has revealed that existing firefighting methods used to extinguish machinery space spray and pool fires on conventionally-fuelled vessels are inadequate when dealing with methanol-based fires.
This follows extensive comparative fire tests on dual-fuel marine engines using diesel oil and methanol, carried out amid growing interest in methanol as an alternative marine fuel.
Michał Sadzyński, Product Manager for Water Mist Systems at Survitec, said the tests confirm that traditional water mist fire suppression mechanisms do not perform as expected on methanol pool fires and methanol spray fires and that a completely different approach is required if ships are to remain safe.
Methanol is a methyl alcohol that burns in a completely different way than hydrocarbon fuels and has a much lower flashpoint of 12°C. However, while there are established fire safety regulations and testing standards for diesel fuels, clear test protocols for alcohol-based fuels such as methanol and ethanol have yet to be developed.
The Survitec tests found that while water mist systems are highly effective in absorbing heat and displacing oxygen on diesel fires, they do not produce the same results on methanol fires.
Also, traditional nozzle placement and spacing needed to be modified to make water mist suppression effective on methanol. For instance, the tests showed the range for nozzle installation height is much lower than that needed to put out a diesel fire.
Survitec said this finding indicates that if existing vessels are retrofitted to run on methanol, there would be a need for these to be overhauled and have their fixed fire-fighting arrangements redesigned completely.
For bilge areas, statutory rules formulated in IMO MSC.1/Circ.1621 establish a requirement for an approved alcohol-resistant foam system for ships running on methanol. For the first time, a fixed, low expansion foam system is mandatory under the rules when it comes to protecting machinery space bilges.
Maciej Nieścioruk, Product Manager for Foam Systems at Survitec, said the tests demonstrate that standard discharge devices do not properly extinguish methanol pool fires in the confined bilge space, hence the need to deliver properly expanded foam on the methanol pool fire, which is challenging within a narrow space where throw length is limited.