Principles of firefighting
Speaking about the firefighting it necessary to understand the nature of fire. It can be easily showed by fire triangular. The fire occurs when in one moment three factors join together: fuel, air and heat. In modern practice instead of fire triangular the fire tetrahedron is used. The fourth factor is a chain reaction.
The heat and fuel are subdivided into several classes to provide effective and prompt firefighting. Fuel is subdivided into carbonations materials, hameable gases and hameable liquids and the heat represents by radiation (transfers the energy without contact), conduction (no direct flame but sufficient heat) and convention (warm air rises and circulates).
The main source of ignition is heat. It can be sparks from welding, funnel sparks, cigarettes, naked flame, impacts, overloaded circuits, short circuits or spontaneous combustion.
Measures for fire preventing are one of the main part of the ship’s safety whether she is at sea, at the berth or in dry dock. The Safe Working Practices should be followed. It means good housekeeping, cleanliness, maintenance of electrical circuits and regularly personnel trainings. It is also necessary not to forget to turn off ovens when hot in use, not to overheat boilers, keep the ventilation hoods and filters free from grease. Do not permit oily rags to accumulate and put used rags in close metal containers for disposal.
But if, unfortunately, the fire happened the immediate and prompt actions should taken to respond it. All members of the crew should know what to do in case of fire. They should know the location of necessary equipment, how to operate it and how to escape the accommodation correctly if the fire cannot be extinguished immediately. The word “FIRE” is also the abbreviation which means: Find it, Isolate it, Report it or Raise the alarm and Extinguish it or if it cannot be done by one portable extinguisher Escape it. If someone raises the fire alarm the emergency squad must immediate muster at the headquarters and try to determinate the location of fire, its sources and the scope. Then the emergency squad picks up the equipment, dons fire suits, breathing apparatus and carefully proceeds to the place of fire. Usually the fire squad consists of noselman and back up.
There are two types of firefighting systems: portable and fixed. Portable media are convenient to deal with the small fire. But if the scope of fire is too big the fixed systems are preferable. The portable media are fire extinguishers and fire blankets. Fixed systems are inert gas, CO2, foam system, sprinkler system.
To extinguish the fire it is necessary to remove one the part of fire triangular. Removing heat its cooling, removing fuel its starvation and removing air its smothering. Cooling is provided by water or water spray, starvation by cutting off the supply of liquid flammables or gases and smothering can be done by fire blanket, CO2, water spray or foam.
For better result different types of fuel should be extinguished by special firefighting substances such as water, foam, CO2 and dry powder. Water is preferable for extinguishing carbonations materials and not efficient for extinguishing the inflammable liquid, electrical and gaseous in this cases water even deteriorates the situation. Foam is used for extinguishing the inflammable liquids and carbonations. CO2 is convenient for smothering the electrical, gives some effect for inflammable liquids and low efficient for carbonations as it does not remove heat. And, finally, the dry powder capable to deal with all types of fires but it the expensive medium.
In conclusion its necessary to say that its better to prevent the fire then to fight with it. But in case of fire on board the actions must be efficient and prompt.
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