Being able to properly identify a type of fire and the extinguisher that is used to put it out is something that everyone should know. It's a skill that hopefully you will never have to use but if you do have to it may save your life or even someone else's. For this reason its important to have this knowledge rather than not have it. This article will break down the types of fire extinguishers and what fires they are used to extinguish.
Type A
Type A fire extinguishers are used to put out fires that have wood, paper, trash or other combustible materials. They are mostly used on fires with organic materials as a fuel source. They can be used on plastic fires as well.
The contents of the extinguisher can be either foam or water both of which are effective. They should not be used to try and extinguish any other type of fire. This will only create more of a hazard.
Type B
Type B extinguisher are used to put out fires that are caused by flammable or combustible liquids. These could include gasoline, lighter fluid, alcohol, kerosene, acetone and cooking oil. They are also effective against combustible gases as well.
These types of extinguisher contain pressurized CO2 or Carbon Dioxide and will starve a fire of its oxygen. These can be hazardous to people if it is sprayed directly at someone which will also displace oxygen in the immediate area. CO2 extinguishers are ineffective against Class A (Organic materials) fires but are effective against Class C (Electrical).
Type C
Type C extinguishers are used to put out electrical fires. This includes wiring, computers, fuse boxes or electrical equipment. These types leave a large amount of residue behind after they are used. The residue is notoriously hard to clean up and usually results in furniture and carpets being replaced.
Type C extinguishers used CO2 and a Dry Chemical agent in combination to extinguish fires. The dry chemical agent is a mixture of different components. Some modern versions are filled with what is called a "clean agent" sometimes called Halotron which leaves no residue but is still harmful to people. Type C extinguishers can also be used on Class B (Flammable liquids) fires.
Type D
Type D extinguishers are used to extinguish fires caused by combustible metals, metal flakes and powders. Combustible metals include potassium, sodium, magnesium and titanium. These types of fires are relatively rare. Normally extinguishers of these types will be place very close to a potential hazard and their contents will be specific to the type of metal in the area.
A common chemical found inside these extinguishers is Sodium Chloride (NaCl) which is common table salt. If a situation arises where one of these fires occurs and there is no extinguisher suitable then pouring table salt on it may actually work.
Type K
Type K extinguishers are specific to kitchens or commercial and industrial food preparation. They are designed to put out fires caused by grease, cooking oils and animal fat. It is not required to have one in a residential kitchen but grease fires are common and if one gets too big this would help greatly.
These extinguishers spray a fine mist of wet or dry chemicals and can be used at a good distance. These can spray up to 30 feet which gives plenty of distance between a person and the fire. A common chemical found inside one of these extinguishers is Potassium Hydrogen Bicarbonate (KHCO3) which is "generally recognized as safe" and is even used in small amounts as a food additive.
Multi Purpose
These types of extinguishers are commonly made to extinguish types A, B and C fires. They are growing in popularity because they are so versatile and in many places are preferred.
These extinguishers are filled with a dry chemical called Monoammonium Phosphate which will leave a thick, sticky residue behind after use. The chemical is a dull yellow colour and if it is left alone after use will cake making it very difficult to clean up. However it is soluble in cold water. It is also hazardous to humans if inhaled and will permeate though skin if not cleaned off. Ingestion is a much lower risk.
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