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.