Fire class · UK/EU and US
Class D: burning metals
First: raise the alarm, get out, call the fire service
UK: However, if in doubt, employees should not put themselves or anyone else at risk, but simply raise the alarm, leave the premises, and call the fire and rescue service.
HM Government (GOV.UK), A guide to making your small non-domestic premises safe from fire (accessible version), section ‘Fire extinguishers’
US: If you're unsure about whether it is safe to use a fire extinguisher, and for all other situations, alert others, leave the building, and call 911 from a mobile or neighbor's phone.
US Fire Administration (FEMA), Choosing and Using Fire Extinguishers, ‘Help people decide when to use a fire extinguisher’
Metals: magnesium, aluminium, lithium, sodium.
UK and Europe (BS EN 2 classes)
Fires involving metals.
HM Government (GOV.UK), Fire safety risk assessment: offices and shops (accessible version), Part 2, 3.1, Table 1: Class of fireClass D fires caused by combustible metals including potassium, aluminium or magnesium among others
Surrey County Council (Surrey Fire and Rescue Service), Extinguishers and fire blankets, ‘Fire Classes’
United States (NFPA 10 classes)
Fires in combustible metals, such as magnesium, titanium, zirconium, sodium, lithium, and potassium.
National Fire Protection Association (NFPA), Fire Extinguisher Ratings (NFPA Today blog, Brian O’Connor), table of classesFires involving powders, flakes or shavings of combustible metals such as magnesium, titanium, potassium, and sodium require special extinguishers labeled D.
US Occupational Safety and Health Administration (OSHA), eTool: Evacuation Plans and Procedures, Portable Fire Extinguishers, Extinguisher Basics, Fire classes
Extinguishers the guidance names for Class D
Extinguishers the guidance says not to use on it
- Water:
Do not use on liquid, electrical or metal fires.
HM Government (GOV.UK), Fire safety risk assessment: offices and shops (accessible version), Part 1, 3.4.2, Figure 8 (water) - Foam:
Do not use on electrical or metal fires.
HM Government (GOV.UK), Fire safety risk assessment: offices and shops (accessible version), Part 1, 3.4.2, Figure 8 (foam) - Foam:
This type of fire extinguisher should not be used for fires caused by flammable metals, kitchen fires and fires that involve electrical equipment.
Surrey County Council (Surrey Fire and Rescue Service), Extinguishers and fire blankets, ‘Foam Extinguishers’ - Dry powder (ABC):
Do not use on metal fires.
HM Government (GOV.UK), Fire safety risk assessment: offices and shops (accessible version), Part 1, 3.4.2, Figure 8 (powder) - Carbon dioxide (CO2):
Do not use on metal fires.
HM Government (GOV.UK), Fire safety risk assessment: offices and shops (accessible version), Part 1, 3.4.2, Figure 8 (carbon dioxide) - Wet chemical:
Also keep in mind that if a Class K fire extinguisher is installed, there still needs to be extinguisher(s) available for any other combustible materials in the area since oftentimes a Class K extinguisher can’t be used on an ordinary combustibles fire, flammable liquids fire, electrical fire, or combustible metals fire.
National Fire Protection Association (NFPA), What Is a Class K Fire Extinguisher? (NFPA Today blog, Brian O’Connor), ‘Where should I install Class K fire extinguishers?’
Reading the letter
CLASS D: Fires involving metals Special powder extinguishers (size and type according to risk), dry sand (quantity according to risk). Seek specialist advice.
London Fire Brigade (London Fire Commissioner), Fire Safety Guidance Note GN08: Hand Held Portable Firefighting Equipment, Rev 20, §3.2There are no numbers associated with the Class D ratings of extinguishers.
National Fire Protection Association (NFPA), Fire Extinguisher Ratings (NFPA Today blog, Brian O’Connor), ‘Class D fires’
Other fire classes
Sources
Official guidance only: UK government, UK fire and rescue services, the Fire Industry Association, NFPA, OSHA and the US Fire Administration. Words in quotation marks are theirs.
- HM Government (GOV.UK): Fire safety risk assessment: offices and shops (accessible version) (updated 12 September 2023). Quoted here: Part 2, 3.1, Table 1: Class of fire; Part 1, 3.4.2, Figure 8 (water); Part 1, 3.4.2, Figure 8 (foam); Part 1, 3.4.2, Figure 8 (powder); Part 1, 3.4.2, Figure 8 (carbon dioxide). www.gov.uk Checked 2026-09-29.
- Surrey County Council (Surrey Fire and Rescue Service): Extinguishers and fire blankets (reviewed 24 August 2026). Quoted here: ‘Fire Classes’; ‘Foam Extinguishers’. www.surreycc.gov.uk Checked 2026-09-29.
- National Fire Protection Association (NFPA): Fire Extinguisher Ratings (NFPA Today blog, Brian O’Connor) (26 August 2022). Quoted here: table of classes; ‘Class D fires’. www.nfpa.org Checked 2026-09-29.
- US Occupational Safety and Health Administration (OSHA): eTool: Evacuation Plans and Procedures, Portable Fire Extinguishers, Extinguisher Basics (no date shown). Quoted here: Fire classes. www.osha.gov Checked 2026-09-29.
- HM Government (GOV.UK): A guide to making your small non-domestic premises safe from fire (accessible version) (updated 20 January 2025). Quoted here: section ‘Fire extinguishers’. www.gov.uk Checked 2026-09-29.
- US Fire Administration (FEMA): Choosing and Using Fire Extinguishers (page last reviewed 1 April 2023). Quoted here: ‘Help people decide when to use a fire extinguisher’. www.usfa.fema.gov Checked 2026-09-29.
- National Fire Protection Association (NFPA): What Is a Class K Fire Extinguisher? (NFPA Today blog, Brian O’Connor) (12 August 2024). Quoted here: ‘Where should I install Class K fire extinguishers?’. www.nfpa.org Checked 2026-09-29.
- London Fire Brigade (London Fire Commissioner): Fire Safety Guidance Note GN08: Hand Held Portable Firefighting Equipment, Rev 20 (January 2025). Quoted here: §3.2. www.london-fire.gov.uk Checked 2026-09-29.