A leading authority on fire safety has questioned the continued use of CO2 systems as an approved engine room fixed fire fighting system in the light of the continued incidents of shipboard fires. Frank Rushbrook, principal advisor for the Glasgow-based International Fire Investigators and consultants, says that, since the 1950s, he has been aware of the weaknesses associated with fixed CO2 fire-fighting systems installed for engine room protection. Mr Rushbrook says that half of the fires on ships occur in machinery spaces of one sort or another, and that 60% of these fires cause major damage to the ship. Even after the small fire, over 30% of vessels will require to be towed back to port. The percentage of vessels required to be towed increases as the severity of the fire increases.
In 18% of cases, the fire is extinguished using CO2. However, he argues that this is only part of the story. Mr Rushbrook contends that the effectiveness of CO2 diminishes the longer the fire has been burning. ‘There is a window of opportunity of about one hour’, he advises. But, he adds: ‘only 50% of fires are extinguished within one hour.’ This is due in part, he believes, because CO2 systems are used as a last resort by mariners.
Mr Rushbrook advocates the greater use of water spray-based systems for the protection of engine rooms. He says unlike CO2, which will kill anyone unlucky enough to be trapped in the engine room, water spray can be turned on immediately the incidence of fire has been confirmed.
There is presently a move to design water fog systems for machinery space protection. But Mr Rushbrook believes that the droplet size of the fog could well be to small to tackle really hot fires and, indeed, water gas could be produced, resulting in a dangerous explosion. He says the UK Royal Navy has been conducting research into the benefits of water mist and fine water sprays as part of their search for an adequate halon replacement. Preliminary results suggested that fine water sprays are more effective than water fog. It also found that fine water sprays used in combination with aqueous film-forming foam have proved highly effective.
‘Carbon dioxide has served us well but has the significant drawback that it is, understandably, viewed as a system of last resort by most mariners,’ says Mr Rushbrook. ‘The advances in fire safety engineering in recent years provide the marine community with improved water based systems, systems of first resort, which do not place a Master in the unenviable position of saving the ship but sacrificing crew trapped in a machinery space protected by CO2.’
Full article: Lloyd’s List, January 2000
Further information: Lloyd’s List
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