Fire Triangle | What is Fire Triangle

Fire Triangle | What is Fire Triangle

The fire triangle is a description of the three variables needed to initiate a fire. To set fire, it takes gasoline, oxygen, and heat.

Fire Triangle | What is Fire Triangle

In order to somehow understand the fire triangle, it is necessary to evaluate the influence of each edge of the fire triangle on the combustion process. This study is crucial to the protection manager's understanding of the concept of fire prevention. Fire prevention tries to avoid combining fuel, oxygen, and heat to start a fire. Fire prevention strategies include fuel control, oxygen control, and heat control. There is a discussion on fuels, oxygen and heat sources.


Fuel is a combustible solid, liquid, or gas. As in any chemical reaction, a source of energy is needed to maintain the heat required. The most common solid fuels are wood, paper, cloth, coal, and so on. Fuel and flammable liquids include gasoline, fuel oil, paint, kerosene, and similar materials. Propane, acetylene and natural gas are examples of flammable gases. Solid and liquid fuels have a common characteristic; they must be converted into gas to encourage combustion. Gaseous fuels can experience direct oxidation because the molecules are already in the state of a gas. Many liquid fuels may be directly oxidized as they contain vapors at ambient temperatures and under pressure. However, other liquid fuels and solid fuels are subject to sequential oxidation.

This means that the fuel must first be heated in order to produce sufficient concentrations of the gas to support combustion. From a fire safety point of view, the safety manager should be aware of the different types of fuel in the workplace. The ease of ignition of solid fuel depends on a number of factors. The most important factor is the ratio of surface to the mass of the fuel. The surface-to-mass ratio refers to how much of the surface area of the fuel is exposed to the environment in relation to its total mass. The safety manager should deal with two issues relating to the surface-to-mass ratio of fuel. First, the more surface area that is exposed, the easier it is for a fire to start, and the more exposed it is. Second, the more mass a solid fuel has, the more difficult it will be to initiate and maintain combustion. Consider cotton as a fuel for a textile mill. Cotton dust and lint burn more easily and quickly than a tightly bound bale of cotton. Liquid fuels are affected by several factors. The safety manager should be aware of the terms flash point, fire point, boiling point, and specific gravity. However, a flashpoint should be mentioned as one of the most critical indicators of the flammability of a liquid. The flashpoint refers to the temperature at which adequate vapors are produced to form an inflammable mixture in the air. As a result, a liquid heated to a temperature at or above its flash point will ignite in the presence of an ignition source, such as a spark, cigarette, hot surface, or open flame.


The atmosphere contains approximately 21% oxygen by volume. The oxygen necessary for oxidation is sufficiently supplied from the surrounding air during combustion. When the atmosphere's oxygen content drops below 15 percent, a free-burning fire will start smoldering. When the oxygen content of the atmosphere falls below 8%, a smoldering fire will stop burning (Bryan, 1982). Other sources that release oxygen molecules during a chemical reaction may also provide oxygen. The safety manager should be aware of these oxidizers in the workplace and separate them from all fuels.


The safety manager should be concerned with the sources of heat that are commonly found in the workplace. This is a concern because the sources of heat supply the energy needed to start the combustion process. By preventing heat sources from contacting inflammable fuel-air mixtures, fires can be effectively prevented from occurring. In the workplace some common sources of heat for ignition are:

• Open fires such as torches which are cut and welded

• Cigarette

• Sparks such as from electrical equipment, brazing, or grinding

• Hot surfaces like electric motors, cables, and pipes for processing

• Static discharges, like flammable liquids during the transition

• Quick oxidation or combustion spontaneous ignition combined with proper insulation of a fuel

• Radiated heat from boilers or portable heaters

• Lightning

• Arcing from wires and electrical equipment

• Compression under pressure on a pump, such as hydraulic oil

• Exothermic chemical reactions

Three types of heat transfer are conduction, convection, or radiation. Conduction takes place as two bodies contact each other, and heat is transferred from molecule to molecule. Convection is heat transfer through a moving medium, rather than through direct contact. A medium may be either a gas or a liquid. Radiation is electromagnetic waves being transmitted through any medium.


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