WHY DO CLASS D FIRES OCCUR? Class D fire extinguisher


Combustible metal fires, such as those involving aluminum, titanium, magnesium, lithium, zirconium, sodium, and potassium, are classified as class D fires.

Metal fines, which are tiny, thin pieces of metal that are frequently generated during the machining process and become the fuel element in the fire triangle (fuel, oxygen, heat plus a chemical reaction), ignite and cause these types of fires to typically occur in industrial, manufacturing, or laboratory settings.

class d fire extinguisher

Class D fires are difficult to extinguish and can result in substantial damage.


Regrettably, water or any other extinguishing agent will not effectively put out a Class D fire. Water’s interaction with the combustible metal causes the fire to burn hotter and spread more quickly.

As a result, it is essential that only a Class D fire extinguisher be used to put out a fire caused by combustible metal. Smothering the fires and removing the oxygen source is the most effective approach to put out these fires. The agent also aids in absorbing the fuel’s heat.

Dry Powder extinguishers are the only form of Class D fire extinguisher currently available. The fuel (the ignited flammable metal) and oxygen can be separated using a powder agent made of either powdered graphite, granular sodium chloride, or copper.

Dry powder extinguishers can put out Class D fires, but they are useless against any other kind of fire.

It is crucial that people who work with combustible metals comprehend the special characteristics of Class D fires as well as how (and when) to use a Class D fire extinguisher safely and effectively.


Do you own, run, or work in a place where flammable metals are handled? If so, it’s crucial that a Class D fire extinguisher protect both you and your staff.

Having the appropriate fire extinguisher for your needs may be a concern if you

dangers, contact Koorsen’s specialists. They may assist in ensuring that the best extinguishers for your environment are used to protect you and your possessions. To increase everyone’s safety, Koorsen may also give you and your staff fire extinguisher training. Call them right away.classifications for extinguishers and fires

Types of fires

  • A class

Ordinary flammable materials like cloth, wood, paper, rubber, and many types of polymers are involved in class A fires. A-rated extinguishers are made to put out fires involving these common flammable items.

  • B Class

Liquids that are flammable and combustible, like gasoline, alcohol, oil-based paints, and lacquers, are involved in class B fires. Extinguishers with a B grade are therefore made to put out flames involving flammable and combustible liquids.

A fire involving flammable gas should not be put out until there is reasonable assurance that the fuel source can be quickly disconnected. In fact, cutting off the fuel supply is the best way to put out a fire if the only fuel burning is leaking gas. Without turning off the fuel, putting out a flammable gas fire will allow unburned gas to escape into the atmosphere, which could lead to a dangerous buildup of gas that could explode if exposed to an ignition source.

  • Type C

Electrical equipment that is energized is involved in Class C fires. Extinguishers with a C rating are made to be used on fires involving electrical equipment that is electrified.

  • D class

Combustible metals like sodium, titanium, and magnesium are involved in class D fires. D-rated extinguishers are used to put out fires involving flammable metals.

A flammable metal fire may react with common extinguishing solutions, intensifying the fire’s severity. The most popular way to put out a fire made of combustible metal is to cover the burning material with a dry powder that won’t react with it, like sand. Contact the Fire Prevention Services office for advice on the right kind and quantity of extinguishing chemical you should have on hand if you store or use combustible metals.

  • Grade K

Vegetable oils, animal oils, or fats in cooking appliances cause Class K fires. Extinguishers with a K rating are made to put out flames caused by fats, oils, or oils used in commercial cooking equipment.

Note: Where deep fryers and/or griddles are used to make big quantities of food, extinguishers with a K rating are typically necessary. An illustration would be a commercial kitchen like those in cafeterias and restaurants.

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