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Fixed Fire-suppression Systems – The Engine Room
Janine
Posted: Friday, July 6, 2012 9:00 PM
Joined: 02/05/2008
Posts: 392


When is it appropriate for the crew to attack a shipboard fire and when should you use the installed fire-suppression system? Every fire scenario is different as are the experiences and capabilities of every crewmember and every captain’s decision-making process. The use of a fixed fire-suppression system may not always be warranted. On the other hand, use of the fixed system is the safer means of extinguishing a fire as it lessens the danger for crew.

Locations and uses of fixed fire suppression systems
The engine room is the area of highest fire probability on board. All engine rooms are equipped with some form of fire protection such as Carbon Dioxide, Hi-Fog, FM-200 or possibly Halon.

Engine room fires most often are caused by cracked or broken pressurized fuel lines. Fuel lines could be constructed of copper, nickel-copper or copper-nickel. The constant vibrations in the engine room and the forces that act on the vessel as it travels through the water can cause the fuel lines to weaken and eventually crack over time. When a fuel line cracks the fuel is converted from a liquid to vapor form. It is this vapor that poses the greatest risk of fire. Fuel spraying out of the cracked fuel line can hit the exhaust manifold or other heated surfaces on the engine and ignite.

Today, most vessels are so technologically advanced that a fuel line leak would be detected almost instantly. Prompt discovery and quick response by the crew — by shutting down the fuel pumps — greatly reduce the potential damage from a fire. Even with quick discovery and response, the resulting fire could quickly overwhelm the capabilities of a portable extinguisher. The fixed suppression system is the better choice. Making that decision quickly will ensure the greatest possibility of success. If the fire team spends more time trying to fight the fire with extinguishers, it is less likely that the fixed system will extinguish the fire. Once the decision is made to use a fixed system, immediately shut down the fuel, power and ventilation systems, evacuate the crew, close all doors and access points to the engine room and follow the steps for discharging the fixed system.  

Upon discharge of the system, there must be verification that the system has actually discharged and the fire has been extinguished. To verify that the system has discharged, check video surveillance in the engine room. If there is no video surveillance equipment, check for heat on the door or bulkhead surrounding the affected space. This check could be done with a thermal imaging camera or by using the back of your hand. When checking for heat with either option, choose a place on the door or bulkhead and check that same spot at five- or 10-minute intervals. You will be looking for or feeling for an indication that the thermal layer/heat layer has risen up the door or bulkhead. This will signal that the fire has been extinguished. If the thermal layer or heat layer is holding constant or continuing down the door or bulkhead, this is an indication that the fire has been not extinguished and a new plan of fire attack must be developed. You also can check the fire detection system, if it allows temperature monitoring via heat detectors. If your engine room is protected by Class A or A-60 bulkheads and doors, the verification will be more difficult. You will have to check other areas, such as doorknobs, door frames or structural components that abut or share the engine room bulkhead.

If your verification indicates that the fire is extinguished, continue temperature checks and leave the space locked down until cool. How long is long enough to leave the space in lockdown? The answer is as long as possible. You must give the space sufficient time to cool to a safe temperature; twenty-four hours is one recommendation.

There are a couple ways to determine the appropriate timing. First, confirm several significant temperature drops in the area or allow the air temperature to cool below the lowest flash point of a combustible material in the engine room (diesel fuel for example has a flash point of 110 degrees F). Therefore, you would allow the engine room to cool below that temperature. Once you have waited an appropriate period of time and reentry to the engine room seems reasonable, prepare crew in fire gear and carefully enter the engine room to begin to assess damage.  

By Tom Jones,  training manager at Resolve Maritime Academy, 1510 S.E. 17 St., Suite 400, Ft. Lauderdale, FL 33316 Tel: 877-975-3473 info@ resolveacademy.com www.resolveacademy.com

Rusty Wrench
Posted: Friday, July 6, 2012 9:53 PM
Joined: 21/09/2010
Posts: 207


High pressure fuel lines are made from heat-treated steel.
Chief
Posted: Friday, July 6, 2012 11:00 PM
Joined: 02/06/2008
Posts: 342


If your fuel supplier is delivering marine diesel the flash point had better be at or above 60*C or 140*F.

 

If you are loading automotive diesel pretending to be marine diesel it may have a flashpoint as low as 38*C or 100*F.

 

If you are on a plastic boat all bets are off in any event ... as should you and everyone else.