In addition to the well-known fire classes A, B, and C—which classify fires involving solid, liquid, or liquefying substances and gaseous substances—there is also fire class D. This class includes fires involving metals, which pose particular hazards and require the use of special extinguishing agents and techniques.
Metal fires often occur as a result of overheating or flying sparks in industrial processes. Improper extinguishing can trigger violent reactions, and in extreme cases even explosions. This makes it all the more important to be familiar with the characteristics of this fire class and to take appropriate protective measures at an early stage.
What is included in fire class D?
Typical substances in fire class D include:
- Aluminum
- Magnesium
- Titanium
- Sodium
- Potassium
- Lithium
These metals can self-ignite at high temperatures and burn with enormous heat—sometimes over 2,000°C. Particularly dangerous: Reaction with water or conventional extinguishing agents can lead to explosions or the release of flammable gases. It is therefore essential to take targeted and professional action in the event of metal fires.
Where do metal fires occur?
Class D fires occur primarily in areas where highly flammable metals are used. Typical areas of application are:
- Metalworking companies (e.g., turning shops, foundries)
- Workshops and production halls
- Research facilities and laboratories
- Battery manufacturing and recycling
- Storage facilities for metal chips or powder
Finely dispersed substances such as metal dust or chips are particularly dangerous, as they ignite more easily and can accelerate the development of a fire.
Which extinguishing agents are suitable for fire class D?
Metal fires must not be fought with water, foam, or CO₂ extinguishers. These agents are not only ineffective, but can also trigger dangerous chemical reactions.
Instead, special metal fire extinguishing agents are used, including:
- Sodium chloride (table salt)
- Graphite powder
- Copper powder
- Dry sand (in exceptional cases)
These extinguishing agents work by binding heat and forming a barrier layer that shields the source of the fire from oxygen. It is important to select the appropriate extinguishing agent for the metal that is burning.
Fire extinguishers for class D fires
Special D fire extinguishers can be used to fight metal fires. These are filled with suitable metal fire powders.
Safety tips for dealing with metal fires
- Keep a safe distance from the source of the fire – metal fires generate extreme heat and flying sparks.
- Notify the fire department immediately – and explicitly mention that it is a metal fire.
- Train your employees regularly so that they can act quickly and safely in an emergency.
- Refrain from attempting to extinguish the fire yourself if this puts you at risk – especially when using water or unsuitable extinguishing agents, as these can cause violent reactions.
Class D fires are rare, but potentially extremely dangerous. Without the right expertise and equipment, a minor incident can quickly escalate. This makes it all the more important to be prepared.
CWS Fire Safety is your reliable partner for preventive fire protection. We offer individual consultation and practical training courses – for greater safety when dealing with metal fires.
Frequently asked questions
Which materials belong to fire class D?
Fire class D includes combustible metals such as aluminum, magnesium, sodium, potassium, titanium, and lithium—often in powder or chip form.
Where do metal fires typically occur?
They mainly occur in metalworking companies, laboratories, foundries, or battery technology—anywhere where reactive metals are processed.
Which fire extinguishers are suitable?
Only special D fire extinguishers with metal fire extinguishing powders such as sodium chloride or copper powder are suitable for firefighting.