Competence 14: Prevent, control and fight fires onboard KUP 52: Have knowledge of classes and chemistry of fire

KUP 52: Have knowledge of classes and chemistry of fire

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Learning objectives:
1. Understand the classes of fire: Identify and differentiate between the various classes of fire (A, B, C, D, and F) based on the fuel source and type of combustion.
2. Grasp the chemistry of fire: Comprehend the basic principles of fire chemistry, including the fire triangle (heat, fuel, and oxygen) and how these elements interact to cause combustion.
3. Recognize fire behavior: Understand how different fuels and environmental factors influence fire behavior and spread.

Content

Why Are Ship Vessel Fires So Dangerous?

Ship vessel fires are particularly dangerous for several reasons. For starters, ships have limited space, which can restrict crew movement during a fire, making evacuation and firefighting efforts challenging.

Ships are often far from land or emergency services, so the ship’s crews must rely on their own firefighting equipment and resources to combat the fire until help can arrive. In addition, ship ventilation systems can quickly spread smoke and toxic gases throughout the vessel, hindering visibility and causing respiratory issues for crew members.

A fire onboard a ship can compromise its structural integrity, leading to potential hull breaches, collapse of compartments, and sinking. Furthermore, ships carry large amounts of fuel, cargo, chemicals, and other flammable materials that can accelerate the spread of flames and create explosive conditions if ignited [1].

Most importantly, ships have limited access to water supply for firefighting purposes when at sea, even though they are surrounded by water. A fire that burns out of control can easily injure and kill crew members.

Fire classes

There are 6 different classes of fire, depending on the type of “fuel” that is on fire [2].

Class A (Solids): If any type of solid material is burning, like you would expect in a “normal” fire, then it’s a Class A fire.
Class B (Liquids): Many of the fluids, liquids and chemicals used in workplaces can be flammable or explosive. Like cleaning fluids, solvents, fuels, inks, adhesives and paints.
Class C (Gases): This could be natural gas, LPG or other types of gases forming a flammable or explosive atmosphere.
Class D (Metals): Flammable metals include, but are not limited to: Titanium, Aluminum, Calcium, Sodium, Magnesium, Potassium [3]. Metals are also good conductors, helping a fire spread. All metals will soften and melt at high temperatures, which can cause building collapse when metal joists and columns are present in a fire as structural elements.
Electrical Fires: This is not strictly a class (Class E) of fire, because electricity is more of a source of ignition than a fuel.
Class F (Cooking Fats & Oils): Deep fat frying and spillages of flammable oils near heat sources in kitchens can result in a Class F fire.

Fire Extinguisher Classifications

Fire extinguishers have different classifications. The type of fire extinguisher classification relates to the fire type.

Class A fires have a fuel source that’s solid combustible, such as paper and wood. The best types of fire extinguishers for class A fires are water and foam extinguishers.
Class B fires consist of a flammable liquid fuel source, such as gasoline. Should a class B fire ignite, foam or powder extinguishers are the best types of extinguishers to attack this type of fire. CO2 extinguishers can also have limited suitability.
Class C fires are electrical fires (use Class C extinguishers). While extinguishers can be used on Class C gas fires, the only safe method to put out this type of fire is to shut off the gas supply. The best type of extinguisher to put out the fire once the supply of gas is cut off, is a dry powder extinguisher.
Class D: Powder. There are dry powder extinguishers developed to tackle metal fires. The powder inside the extinguisher may vary depending on the type of metal risk it is designed for. Small metal fires can sometimes be smothered with dry earth or sand.
Electrical fire: CO2. The best fire extinguisher to use on electrical fires is the carbon dioxide (CO2) extinguisher. Some dry powder extinguishers are suitable for low-voltage situations. Always turn off the power supply if you can.
Class F: The only type of fire extinguisher approved for use on cooking oils and fats is the wet chemical extinguisher. For small class F fires, you could also use a fire blanket.
Class B fire extinguishers are usually the type of fire extinguisher required on a boat because most fires are gasoline related on marine vessels. The Class B fire extinguisher will have a 5 or 20 before it. The number refers to the square footage that the fire extinguisher will cover [3].

Recommendation

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