Bad, confusing design is a hazard we don’t hear about very much but in an emergency the difference between good design and bad design may be the narrow gap between success and tragedy. Take a look at the picture at the top of this page: Can you immediately tell which tags to pull to cut off fuel and which to pull to activate the CO2 fire suppression system? In the dark? In rough weather? In a hurry?
Unplanned releases of carbon dioxide can have tragic results. It can extinguish lives as easily as it can put out fires so it’s vital to ensure that the CO2 cylindre room is isolated when someone’s working on the fire extinguishing system, as a recent report from the UK’s Marine Accident Investigation Branch, MAIB, highlights.
It shouldn’t happen, but it does. Is your emergency response prepared?
On 23 August 2011, a shore-based service engineer was seriously injured on board the tug SD Nimble when six cylinders of carbon dioxide were accidentally discharged shortly after the tug had slipped from her berth in Her Majesty’s naval base in Faslane, Scotland.
The engineer was testing components of the vessel’s fixed carbon dioxide fire extinguishing system in the carbon dioxide cylinder room. The accidental discharge of carbon dioxide caused a depletion of oxygen levels in the cylinder room and aft hold causing the engineer to quickly lose consciousness. The tug was immediately manoeuvred back alongside and
the service engineer was quickly recovered onto the open deck, where cardio pulmonary resuscitation was started. The engineer was subsequently transferred by helicopter to the Southern General Hospital in Glasgow where, following a long period of recuperation and therapy, he made a good recovery.
CO2 not only puts out fires, it also puts out life. You really don’t want an engine room, or anywhere else flooding with it when there are people inside, as almost happened aboard Marsol Pride. Frighteningly it’s a case in which maintenance procedures were complaint with IMO requirements but the equipment was dangerous.
On 23 May 2010 the general-purpose oilfield support vessel Marsol Pride was conducting underwater operations within the Tui oil and gas field off the west coast of New Zealand. Marsol Pride was fitted with a fixed carbon dioxide (CO2) fire smothering system for its engine room. Late that night a valve on one of the CO2 pilot cylinders developed a leak and charged the system ready for release. A second leak in the main control valve then caused the entire system to activate resulting in an uncontrolled release of CO2 gas into the engine room. An automatic alarm in the engine room had warned the duty engineer there of the impending release so he had left the engine room to investigate the reason for the alarm. The incident caused one of the 2 main propulsion engines to shut down due to air starvation; other than that there was no damage to the vessel and no one was injured. An uncontrolled or inadvertent activation of an engine room fixed CO2 gas fire smothering system is a serious event because the CO2 gas displaces any air in the space so that it cannot sustain human life, and it can immobilise the ships propulsion and generator systems at a critical part of an operation.
ANSUL – High Pressure Carbon Dioxide fire extinguishing systems:
There have been several instances where this particular fire extinguishing system has discharged without human intentional or accidental involvement.