Fire on a basic principle is a chemical reaction involving two reactants: fuel and oxygen. The activation energy needed to trigger this reaction is measured by the reactants temperature and is referred to as the temperature of ignition. Propagation of the reaction will continue for as long as the three requirements are met (i.e. Temperature, fuel, & oxygen). A decrease in any of these results in a limitation of the reaction and therefore is the basis for fire containment. In the process for fire, the fuel degenerates to a molecular level and combines with oxygen forming superheated gasses. This oxidation reaction produces a flame of expelled gases illuminated in part by the suspended high temperature carbon radical particles. The flame color also depends on the temperature of the burn and what particle is present due to the decomposition of the fuel. Fiberglass has a very high temperature of ignition and difficult to contain. It also releases carbon monoxide, carbon dioxide and hydrocarbons when burning making enclosed areas extremely hazardous. The difficulties of boat born fires demand a quick response for containment balanced by the strong practice of personal safety.
Containment of fire requires the limitation of the fuel, oxygen or temperature. Fire Extinguishers are available to perform this task in a number of ways.
- Water fire extinguishers reduce the temperature of the fuel. Applicable to wood and paper products it should not be used on electrical or liquids fires. Water, unless de-ionized, will conduct electricity placing the user at risk for potential electrocution; additionally fire extinguishers that use an expellant directly on the fire can spread the burn when applied across a liquid fuel fed fire. For instance, water extinguishers are not recommended for an oil fire because the force of the water can spread the burn. To make matters worse, the high temperatures of the oil fire can cause water to breakdown releasing oxygen and further feeding the fire.
- Fire extinguishers filled with carbon dioxide rob the reaction of oxygen. Carbon dioxide gas is heavier than oxygen and therefore separates its interaction with the fuel by displacing it. Dry chemicals, such as sodium bicarbonate and potassium phosphate, delivered via foam or powder not only make a physical barrier when applied, they decomposes into carbon dioxide creating an oxygen devoid blanket over the fuel adding an additional barrier. This two-part suppression helps prevent flash ignitions. However some foam may carry the same cautionary warning prescribed to water fire extinguishers, namely electrical and liquid fire precautions.
The universal coding is depicted in a pictorial manner along with an alphameric class designation:
[A] Wood, paper, cloth, trash, plastics, solid combustible materials that are not metals. (Class A fires generally leave an Ash.)
[B] Flammable liquids: gasoline, oil, grease, and acetone, any non-metal in a liquid state, on fire. This classification also includes flammable gases. (Class B fires generally involve materials that Boil or Bubble.)
[C] Electrical: energized electrical equipment, as long as it's "plugged in," it would be considered a class C fire. (Class C fires generally deal with electrical Current.)
[D] Metals: potassium (K), sodium (Na), aluminum (Al), magnesium (Mg).
Since all fire extinguishers inhibit fire at the fuel-oxygen interface the force of the expellant should be directed at the base of the fire. This will effectively "coat" the fuel and reduce the burn.
Additional methods of fire suppression are available which retard the abundance of oxygen instead of the actual reaction. These are usually referred to as clean systems because they do not deposit residue, whereas conventional fire extinguishers will (with the exception of carbon dioxide). These are known as suffocant systems because they eliminate oxygen as a fuel source. They are also known commonly as "halon" systems even though they no longer contain the chemical for environmental reasons. The chemical Halon was prohibited from being manufactured in the early 90's. It poses as an environmental threat attacking ozone at a much greater rate then chlorofluorocarbons (CFCs). Although Halon is no longer manufactured, systems already in place are typically overlooked by regulatory agencies, limited only by set guidelines. Regardless of the type of chemical (Halon 1221/1301/2402, INERGEN, FM-200 , FE-13, FE-25, etc.) these systems use the same principle. The fluorocarbons of all suffocant systems essentially have the ability to bind to multiple oxygen atoms leaving the fire without the key component of oxygen. This means it is important to use caution when discharging the fire suppression system in inhabited areas. These systems will remove oxygen and can pose a respiratory threat to humans in the vicinity. Therefore, it is important to make sure that the application fits the manufacturer's specifications for deployment. On the other hand, these systems are very effective and useful, leaving no residue to cleanup. Also, they extinguish multiple fires in an enclosed area because they essentially remove oxygen as a fuel source.
FM-200 is the most accepted and safest fire extinguishing agent on the market today. FM-200 delivers optimum extinguishing performance in just seconds, operating primarily by removing heat energy from fire and inhibiting combustion. Since FM-200 is a clean gaseous vapor, there is not the traditional clean up of fire extinguisher powder, foam or residue. Thus, sensitive equipment including radar, electronics and the engine itself are not damaged and can be fully operational following fire extinguisher activation. Vessels using FM-200 Sea-Fire fire extinguishers and suppression systems, often see their insurance rates decrease. FM-200 fire extinguishers are extremely safe for people as well. Over 70 industry toxicity test verify its safe use in occupied areas. FM-200 is recognized as the premier Halon replacement and enjoys worldwide acceptance. FM-200 is replacing CFC propellants in pharmaceutical inhalers, including asthma dispensers. Designed to produce non-toxic and non-corrosive protection, the agent is also non-ozone depleting. FM-200 is not subject to any environmental phase-out schedule and has received worldwide environmental approval.
Safety on a boat is the number one priority. Steps should always be taken ensure the protection of its passengers and crew before expending effort on the fire: lifejackets should be donned, coastguard contacted, and other nearing vessels warned. When confronting the fire, try to separate combustibles or obvious fire fuel if possible. With the gasses produced from plastics, fiberglass and foam found on many boats, you might have very little time before inhalation becomes a problem. DO NOT spend large amounts of time trying to out think the fire. If you can, properly discharge the fire extinguisher and move on to safety issues. This is where a properly installed suppression system is ideal. Manual or automatic, the system is ready to be triggered leaving you time deal with other safety issues. Systems that are automatic have the additional benefit of being triggered without going below deck or even being on the boat. These systems can also be installed with distribution hoses that deliver the needed retardant directly to the fire related incident.
Remember to have your fire extinguishers, suppressant systems and detectors checked regularly. It's also an important to keep those service tags attached and up to date.
