What Do The Symbols On A Fire Extinguisher Indicate? A, B, C, D & K Explained (2024)

FAQs

What Do The Symbols On A Fire Extinguisher Indicate? A, B, C, D & K Explained? ›

There are five extinguisher classes based on what type it is intended for – letters A, B, C, D, and K. A for easily combustible things, B is for highly flammable liquids, C is intended for electrical fires, D for metals that cause fire, and lastly K is for kitchen fire associated with cooking oils and fats.

What do markings on fire extinguishers mean? Markings on fire extinguishers identify the classes of fires they are designed to extinguish, with each symbol representing a specific fire class—A for ordinary combustibles, B for flammable liquids, C for electrical fires, D for combustible metals, and K for kitchen fires.

Fire Extinguisher Classes

Class B puts out flammable liquid fires (oil, gas, petroleum, etc.) Class C puts out electrical fires. Class D puts out combustible metal fires (magnesium, titanium, potassium, sodium, etc.) Class K puts out cooking fires ignited by flammable oil and grease.

Class K fire extinguishers are more effective in extinguishing cooking fires. They use wet chemical agents with a greater firefighting and cooling effect for this type of hazard.

ABC of Fire Extinguisher represents the classification of fire extinguishers by the type of fires they can put out; A - Ordinary combustibles, C - Electrical equipment, B - Burning liquids and gases and D - Metal Fires.

The C classification means the extinguishing agent is non-conductive. The geometric symbol indicating Class C is a blue circle.

The numbers in front of the letters represent the relative amount of that type of fire which the extinguisher will put out. So a 2A 40BC fire extinguisher will put out 4 times more of a “B” fire (flammable liquid) than a 2A 10BC fire extinguisher.

A class D fire extinguisher is used on fires that involve combustible metals. This type of fire, which can cause significant damage, often occurs when small pieces of metal or dust that are generated during processes in a manufacturing, industrial, or laboratory setting ignite.

Class B: liquids or gas such as alcohol, ether, gasoline, or grease. Class C: electrical failure from appliances, electronic equipment, and wiring. Class D: metallic substances such as sodium, titanium, zirconium, or magnesium. Class K: grease or oil fires specifically from cooking.

A Class K fire is fueled by flammable cooking liquids, such as cooking oil, and animal or vegetable-based greases. These liquids, when brought up to high temperatures, become volatile and can easily ignite. Due to their high flammability, they also spread rapidly.

What is K vs B fire extinguisher? ›

While Class K fires do involve flammable liquids, please be aware that Class B fire extinguishers (rated for flammable liquids such as petroleum and gases) are not efficient to handle the high-temperature cooking oil and grease fires that occur in kitchens.

Class "K" fires, or kitchen-based fires, are often overlooked but account for the majority of fires that ravage our homes and lives. They're extremely difficult to douse because they combine electrified elements with dangerous liquids and gasses.

A Class C fire extinguisher is used to extinguish a fire that is caused by an energized electrical element. If the source of power is removed from the fire, it no longer qualifies as a class C fire and becomes one of the other classes of fire. However, removing the power source is not always possible.

Class D fires are fires which involve combustible metals.

Because of this, class D fires are more likely to be found in commercial or industrial environments – anywhere metal work, such as cutting or drilling, is carried out. Examples of combustible metals are: titanium, potassium, lithium and magnesium.

What is a Class C fire? Class C fires are identified by the presence of a burning gas. The most common flammable gases involved in fires are propane, butane and methane, and they form the 'fuel' aspect of the fire triangle, which is required for the fire to start, spread and continue to burn.

The designation is the letter B in a red square. A memory aid for Class B fires is that a flammable liquid must Boil and give off vapors to burn.

The letter on a fire extinguisher indicates its classification: Class A puts out ordinary combustible fires (wood, paper, plastic, etc.). Class B puts out flammable liquid fires (oil, gas, petroleum, etc.). Class C puts out electrical fires.

Color Coding of Fire Extinguishers

Water and Foam: Red with a green triangle (Class A). Carbon Dioxide (CO2): Red with a black square (Class B and C). Dry Chemical: Multi-purpose with a blue circle (Class A, B, and C). Wet Chemical: Oatmeal color with a black hexagon (Class K).

Extinguishers suitable for Class A fires should be identified by a triangle containing the letter "A." If colored, the triangle should be green. Extinguishers suitable for Class B fires should be identified by a square containing the letter "B." If colored, the square shall be colored red.

U.S. Army Corps of Engineers, Water Safety

To find out if your fire extinguisher is expired, the year it was manufactured is usually stamped on the bottom or some have a year marked next to the Underwriters Lab (UL) label.