A fire extinguisher is usually a vessel containing an agent that can actively control a fire. It is an emergency measure to mitigate small occurrences in a small area. They are not designed to fight fires that have gotten out of control or those that endanger the user. These items are installed in many locations as a safety precaution especially in high risk zones. The classification of fire extinguisher types will depend on the criteria used to differentiate them. Having the right information on what type to purchase or use in case of various types of fires is important can mitigate risks. You also need to ensure that any fire extinguisher service has the appropriate fire extinguisher maintenance contract in place.
Classification by Operation
There are two fire extinguisher types depending on how they are operated. This is a technical division that is not commonly used colloquially.
Stored pressure: These are commonly used units where the expellant and the agent that extinguishes the fire are stored in the same chamber. Different kinds of propellants are used for every agent to enhance the effectiveness of the extinguisher.
Cartridge-Operated: These are units that have the expellants and the agent in separate chambers. They are easy to use and require only puncturing of the expellant chamber to perform the task. Because of this, they are found in high-risk areas where small fires are commonly experienced such as industrial sites.
Classification by Type of Fire
The causes of fire vary and they cannot all be controlled using the same agent. For instance the use of water to extinguish a fire fuelled by oil will only help it in spreading. This is the most popular criteria because it is easy to understand and the information is straight-forward. There are alphabetical indicators for this type of rating and the colored shapes within which the letters are displayed can also help you distinguish them. This is the most reliable criterion in identification of the right extinguisher and should be known by everyone.
Class A: This is an indicator label for a fire that has ordinary combustible material such as paper, wood and even plastics. The indicator shape is a green triangle and a handy mnemonic to recall is Ash’. There are different agents used in these cases but primarily, monoammonium phosphate is used. They have a numerical rating that shows the amount of water within the vessel.
Class B: This is an extinguisher usually used to deal with fires resulting from flammable liquids. For easy recall, the letter is in a red square and one can think of a “Barrel”. The common liquids are kerosene, gasoline and grease among others. These fires are quite dangerous and there are two agents commonly used as agents for control. Monoammonium phosphate and sodium bicarbonate smothers the fire and extinguishes respectively. The rating that is presented is usually an approximation of the area that the extinguisher can cover.
Class C: These fires are caused by live “Current” and can therefore not be extinguished by any agent that is capable of conducting electricity. The frequency of electrical equipment catching fire is quite high and should be dealt with safely. Similar agents to the Class B are commonly used since they are not conductors. The symbol used is a blue circle and no ratings are used for this class.
Class D: This is one of the special fire extinguisher types that cannot be used for multiple purposes like in the A, B and C. The indicator symbol is a yellow pentagram and a good mnemonic to recall its use is Dynamite’. They are usually found in laboratories and are useful for combustible metals such as potassium, sodium and even titanium. Unlike the first three, Class D vessels are not red but a distinctive yellow color.
Class K: This is found primarily in Kitchen’ environments and is identified by the black hexagon symbol. Like Class D, they are not red; the vessel is usually silver or white. They deal with fires that result from cooking oils and fats especially in restaurant environments.
Recognition of these separate classes is more important than knowing exactly what is inside the canister. It is important to have at least a single fire extinguisher at home in case of emergency. When buying one, consider the likely cause of fire for the place that you will install it. When an incident occurs, it is vital to remember that using the wrong type could be potentially fatal. Consider retaining the helpful information to avoid being at risk.