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29/08/2025 • by Megan Downing
In any place where metalwork is carried out, it is crucial to understand the risks of Class D fires. These fires involve flammable metals, which are most often found in industrial and commercial settings.
In this blog, we'll break down everything you need to know about Class D fires, including what they are, how they start, how to safely put them out, and our top recommendations for the best Class D fire extinguishers.
At Fire Protection Shop, we have supported thousands of businesses in understanding the fire safety required to protect their premises and people. By the end of this blog, you'll be an expert in Class D fire risks and the steps you need to take to stay safe.
A Class D fire is a fire involving flammable metals such as magnesium, sodium, titanium, aluminium, potassium, and lithium. It is important to recognise that not all metals are flammable, and even flammable metals in large sheets pose less risk of causing Class D fires. The real dangers arise when these metals are reduced small particles or dust during metalworking processes. In this form, they can easily ignite and create highly dangerous class D fires.
In simple terms...
Class D Fire: A fire caused by flammable metals (like magnesium, sodium, or titanium). These fires usually involve small metal particles or dust, not from large solid pieces of metal.
Class D fires are caused by the combustion of flammable metals. This typically occurs when flammable metal fines (like dust and shavings after metal processing) come into contact with sparks, flames, and open heat sources. These fires are difficult to extinguish and require specific extinguishers.
To safely extinguish a Class D Fire, you'll first need to assess if it is safe to do so. Next, make sure you have identified it as a metal fire and use a Class D fire extinguisher. Regular fire extinguishers are unsafe and potentially dangerous when putting out metal fires.
A Class D fire extinguisher is a specialised dry powder extinguisher designed to support putting out a fire started from flammable metals. It is crucial to understand that using the wrong extinguisher, or even water, can make the flames worse, cause an explosion, and have disastrous consequences.
Class D fire extinguishers are used to safely put out fires that involve combustible metals. The dry powder agent works by smothering the fire of oxygen, preventing the fire from spreading.
Class D fire extinguishers are typically identifiable by a violet band with the text L2 Powder or M28 Powder. L2 powder extinguishers are effective on all Class D fires, whereas M28 powder extinguishers are not effective on Lithium.
Place the Class D extinguisher at a safe distance from the fire and pull out the safety pin.
Aim the hose carefully at the base of the fire.
Squeeze the handle to release the powder and move across the area of the fire to smother it of oxygen.
When the fire dies down, you can start to move closer.
Make sure the fire is fully extinguished to prevent it from reigniting.
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