Three things must be present in order for a fire to start. Once a fire begins, removing one of these three things will extinguish it. These three things are sometimes referred to as the fire triangle.
- Heat: this can act as an ignition source or remain present during the entire fire. However, even if the ignition source is removed, once the fire has started it will create its own heat, so the fire will continue to burn. For example, a lighter is used to ignite a cigarette. Once the cigarette is burning it creates its own heat and does not need the lighter any more to continue burning.
- Fuel: this must be some kind of material that is combustible. It can be almost anything, such as wood, cloth, paper, gasoline, diesel, or oil.
- Oxygen: oxygen is all around us at about 21% of the air we breath. In a fire oxygen combines with the fuel. Some chemicals may also release more oxygen while burning. If oxygen is increased during a fire, e.g. opening a window, the fire will increase in strength.
Keeping these three things separated will prevent a fire from starting in the first place. This is why proper storage of flammable materials is so vital.
As mentioned previously, once a fire has started, removing one of the elements from the fire triangle will kill the fire. For example, fire blankets are used to cover a fire so there is less oxygen available; spraying cold water on a flame will remove the heat; and restricting the flow of gasoline will remove the fire's fuel.
There are five classifications of fires and knowing which one is most likely to occur in the workplace is vital because each one requires a different method for putting it out.
- Class A: Solids such as paper and wood.
- Class B: Liquids such as gasoline and oil.
- Class C: Gases such as propane.
- Class D: Metals such as magnesium.
- Class F: Fats e.g. from cooking.
Note: There is no E classification.
There are various types of fire extinguishers. The one to be used will depend on the type of fire. Using the wrong extinguisher may have no affect at all.
- Foam is used for Class A and B fires. It works by smothering the fire.
- Water is used for Class A fires. It cools the fire.
- Carbon dioxide is used for Class A and B. Like foam, it smothers the fire. Warning: A carbon dioxide-based extinguisher will become extremely cold when discharged, to the point of causing severe skin damage, especially the part where the CO2 comes out from.
- Dry powder is used on all types of fires. Works well with electrical fires.
- Liquid vapor is used for Class A and B, and electrical fires. Also smothers the fire.
Causes/Prevention of Fires:
- Electrical: Check for damaged wires, plugs, or sockets. Never overload a socket. Always use the proper fuses.
- Hot works (e.g. welding): Obtain proper training. Obtain proper work permits. Perform risk assessment.
- Improper storage of flammables: Always follow manufacturer's instructions.
- Smoking: Have smoke alarms throughout the workplace.
- Cooking: Use caution with oils. Keep flammables away. Never leave a turned on oven/stove unattended.
- Lightening: Take cover (indoors not under a tree) as soon as there are signs of lightning. Do not hold onto, or stand close to, any metal objects.
Besides extinguishers, workplaces should also have smoke detectors, heat detectors, fire alarms, fire blankets, fire hoses, and sprinklers. All of these should be inspected and maintained regularly. In addition, all workplaces should have fire escape routes and fire drills should be practices regularly. If visitors are at the site they must be told about the exits. If there are workers that may need assistance, e.g. someone in a wheel chair, someone in advance must be assigned the task of assisting them.
What To Do When a Fire Starts
- Sound alarm immediately. This must be done first to warn others.
- Close all windows and doors to prevent the fire from spreading. Exit the area immediately.
- Do NOT waste time collecting personal belongings.
- Do NOT use the elevator, it might fail.
- Do NOT re-enter the building.
- Do NOT attempt to fight a major fire.