The word fire is used to signify the wasteful destruction of combustibles. Strangely enough, man and fire have much in common. Neither can exist without food, warmth and oxygen. For fire, food (in the form of fuel), heat (to cause ignition) and oxygen are the three sides of the fire triangle. These three elements, required for a fire to occur, are air, heat and fuel in vapor form—all combined together at the same time and in the proper proportions. If one of these elements is removed, the fire will not start or will not continue to burn. This is the basic principle for fire prevention and fire extinguishment. As mentioned above, we commonly refer to this as the fire triangle. Modern technology goes one step further to form a tetrahedron to include an uninhibited chain reaction of the combustion process. But for all practical purposes, the fire triangle of air, heat and fuel is all that we need to concern ourselves with.
Practically anything you encounter will burn at some temperature. Of course, some items burn quite readily (wood, diesel fuel, flammable gas, gasoline, paper, and rags) while others (steel and glass) require much higher temperatures to actually burn. We need especially to be concerned with the lower temperature burning items.
Accumulations of trash, debris, or oily rags are favorable fuels for fire. Most petroleum products produce vapors, which form excellent fuel in combination with air. Most of these sources are easily controlled with good housekeeping and operating procedures.
To prevent a fire we must eliminate one ingredient. To extinguish a fire, we must remove one of the elements. Use the appropriate extinguisher for a fire, which is in the class designated on the extinguisher (i.e., a Class A extinguisher on a Class A fire, etc.).
Class A Fires: Class A fires are those that occur in materials such as wood, paper, rags and rubbish, commonly called ordinary combustibles. The quenching and cooling effects of water (removing heat) or of solutions containing large percentages of water are of first importance in extinguishing Class A fires. Special dry chemical agents (multi-purpose dry chemicals) provide rapid knock down of these flames and form a coating that tends to retard further combustion (separation of fuel and air).
Class B Fires: Class B fires are those that occur in the vapor-air mixture over the surface of flammable liquids such as gasoline, oil, grease, paints and thinners. The limiting or removal of air (oxygen) or the combustion inhibiting effect is of primary importance on fires of this class. Solid streams of water are likely to spread the fire. Generally the best method of extinguishment is dry chemical, foam or carbon dioxide.
Class C Fires: Class C fires occur in or near energized electrical equipment and non-conducting extinguishing agents must be used. Dry chemical, carbon dioxide, and vaporizing extinguishers are used on this class of fire. Foam or a stream of water should not be used because both are conductors of electricity and can expose the operators to severe shock hazard.
Familiarize yourself with locations that may constitute a source of fuel for fires. Storage areas of equipment, storage of lube oil and fuels, and electrical equipment should be considered. Areas where rig personnel may congregate, the dog house, change room, living and office quarters are often where a fire is likely to start.
Secondly, familiarize yourself with the location of all fire extinguishment equipment on the rig. Know what class of fires each is rated for, and if an extinguisher is missing, get it replaced.