Definition
Wet Chemical Fire Extinguisher
A wet chemical fire extinguisher is specifically designed for Class F fires involving burning cooking oils and fats. It discharges a fine mist of alkaline potassium solution that reacts with hot oil through saponification — forming a cooling, vapour-suppressing foam — and preventing dangerous re-ignition. Identified by a yellow label panel, it must be serviced annually under BS 5306-3.
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View training courseRelevant UK Standards & Legislation
- BS EN 3Portable fire extinguishers — European performance and construction standard
- BS 5306-3:2017Commissioning and maintenance of portable fire extinguishers
- BS 5306-8:2012Selection and positioning — mandates wet chemical for cooking oil risk
Related Terms
- Foam Fire ExtinguisherFire ExtinguishersA foam fire extinguisher is a portable firefighting device that discharges AFFF (aqueous film-forming foam) to smother fires by forming a vapour-suppressing barrier and cooling the burning material. Effective on Class A (solid combustibles) and Class B (flammable liquids) fires, it is identified by a cream label panel and must be serviced annually under BS 5306-3.View definition
- CO2 Fire ExtinguisherFire ExtinguishersA CO2 (carbon dioxide) fire extinguisher is a portable firefighting device that discharges pressurised carbon dioxide gas to smother a fire by displacing oxygen. It leaves no residue, making it the preferred choice for electrical equipment, server rooms, and environments where contamination cannot be tolerated.View definition
- Dry Powder Fire ExtinguisherFire ExtinguishersA dry powder fire extinguisher discharges a fine chemical powder — typically mono-ammonium phosphate — to interrupt the combustion chain reaction. Effective on Class A, B, and C fires and live electrical equipment, it is identified by a blue label panel. Powder causes significant contamination and poor visibility, so its use in occupied buildings should be a last resort, per BS 5306-8.View definition
- Water Fire ExtinguisherFire ExtinguishersA water fire extinguisher is a portable firefighting device that discharges pressurised water to cool burning materials and prevent re-ignition. Identified by a red label panel, it is effective on Class A fires — solid combustibles such as wood, paper, and textiles — but must never be used on electrical fires, flammable liquids, or cooking oils. Annual servicing is required under BS 5306-3.View definition
Frequently Asked Questions
A wet chemical fire extinguisher is specifically designed for Class F fires involving burning cooking oils and fats. It discharges a fine mist of alkaline potassium solution that reacts with hot oil through saponification — forming a cooling, vapour-suppressing foam — and preventing dangerous re-ignition. Identified by a yellow label panel, it must be serviced annually under BS 5306-3.
Requirements for wet chemical fire extinguisher in the UK depend on the type of premises and applicable legislation, including the Regulatory Reform (Fire Safety) Order 2005 and relevant British Standards. The responsible person for a premises must ensure adequate fire safety provisions are in place. The British Fire Consortium can provide guidance — contact our team or search our member directory to find a qualified specialist.
Wet Chemical Fire Extinguisher and Foam Fire Extinguisher are related fire safety concepts but serve different purposes. See our individual glossary entries for detailed definitions. For expert guidance on which applies to your premises, consult a BFC member company.
The British Fire Consortium offers EAL Level 3 accredited training covering fire safety systems including topics related to wet chemical fire extinguisher. Our courses are the only nationally recognised Level 3 qualifications across all fire disciplines. View our training courses or use the member directory to find a qualified trainer near you.