man using fire extinguisher

Class D Fire Extinguishers: What's Inside and When to Use Them

Working with metals that reach extremely high temperatures can pose a significant hazard and can cause a fire within seconds if given a chance. For this reason, there must be a fire extinguisher close by should the need for it arise.

Combustible metal fires are listed as Class D fires and require a specific extinguisher filled with a particular chemical to put out a fire before it can spread.

If you work with metal regularly, read this article carefully and choose the right fire extinguisher for the potential threat that can quickly get out of control.

What Is a Class D Fire Extinguisher?

Four fire extinguishers sitting next to fire hose in wall case

Keeping a fire extinguisher nearby whenever you are working near combustible materials is crucial to the safety of yourself and everyone around you.

While we all know a fire extinguisher is the first line of defense when snuffing out a spark before it becomes too much to handle, you might not have known that there are specific fire extinguishers for different classes of fire.

Classes of Fire

Types of Fire


Ordinary fires (textiles, wood, paper)


Flammable liquids


Flammable gas


Combustible metals


Electrical fires


Cooking fire (fats and cooking)


With each different type of fire, there is a specific extinguisher designed to dissipate the flame. Each option contains a particular substance best suited for the job at hand. If you choose the wrong extinguisher, you could fuel the flame instead of putting it out.

Types of Fire Extinguishers

You can purchase five main types of fire extinguishers and install them in your home, office, or any other space to provide fire protection to anyone in that area.

These five types of extinguishers include:

  • Water (red label): Fire types A, B, C, F
  • Foam (cream label): Fire types A, B
  • Dry Powder (blue label): A, B, C
  • Carbon Dioxide (black label): B, 🗲
  • Wet Chemical Spray (yellow label): A, B, F

Interestingly enough, you will notice that none of the options listed above is recommended for Class D fires or fires caused by metal combustion.

So what type of fire extinguisher do you need for a Class D fire?

Class D Fire Extinguisher

A Class D fire extinguisher is specifically designed for metal-related fires. They are filled with a special dry powder that can handle almost any fire created with metal.

Typically you will see one of two dry powders inside the canister, which includes sodium bicarbonate or sodium chloride.

So why do Class D fires require a specific type of extinguisher? You need a Class D fire extinguisher because of a specific type of agent to extinguish a fire caused by extremely hot burning metal material.

Only certain chemicals can cool down these hot materials and stop the flames from spreading.

When Do You Use a Class D Fire Extinguisher?

Four fire extinguishers sitting next to fire hose in wall case

A Class D fire extinguisher should be used when a fire erupts from combustible metals. This can be several different materials, including but not limited to:

  • Sodium
  • Magnesium
  • Titanium
  • Potassium
  • Zirconium

You should use the fire extinguisher if the flames are contained and under control. Once the fire is too big or spreads too quickly, it is better to evacuate the building, creating a safe distance between yourself and the flames.

Can You Use Water on a Class D Fire?

You can use water to put out a Class D fire. However, this is only useful if the flames have just started and are in a contained space and on certain metals. Once the metal gets too hot, water will not be able to cool it down quickly enough, so dry powder is the better option.

Another reason to avoid using water on a Class D fire is that there are many situations where it can interact with the metal and create more intense fire, hotter temperatures, and molten metal. This can be a dangerous and life-threatening situation. Sticking to Class D fire extinguishers whenever possible is the best option.

How to Use a Class D Fire Extinguisher

Hand pressing handle of fire extinguisher

Learning how to use a fire extinguisher as soon as possible is beneficial in every way. You don’t ever want to find yourself stuck in a scary situation trying to figure out the mechanics of your life-saving equipment.

Using a Class D fire extinguisher is similar to any other class of fire extinguisher. Each of these products is designed for quick and efficient use.

Just PASS the fire extinguisher to tackle the flames quickly.

  • Pull the pin. (Pull the pin located at the top of the fire extinguisher.)
  • Aim the nozzle. (Point the nozzle towards the base of the flames.)
  • Squeeze the trigger. (To release the product, you have to squeeze the trigger.)
  • Sweep the nozzle. (Move the nozzle of the extinguisher side to side in a slow, steady motion.)

Easy enough and very effective. When putting out a fire with a Class D fire extinguisher, you should be about 8-12 feet away from the flames. This will ensure you don’t get burned yet are close enough to reach the fire effectively.

Where Should Class D Fire Extinguishers Be Located?

Technician with clipboard inspecting fire extinguisher installed on wall

It is recommended that anyone working with metal should have a Class D fire extinguisher within 30 to 75 feet of the potentially hazardous area. This can vary depending on the size of the location and the level of hazard, but only slightly.

These extinguishers should also be at least four inches off the ground but no more than six feet high. This placement will ensure the product is easy to access in case of an emergency.

Final Thoughts

A Class D fire extinguisher is the best way to protect yourself from an extremely dangerous situation when working with metal. Whether you are welding, drilling, cutting, or anything else, if there is a potential for a fire to erupt, having the right extinguisher could be the difference between life and death.

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