- Class A ordinary combustibles where marked
- Class B flammable liquids covered by the rating
- Some paint, fuel or solvent risks after competent assessment
- Mixed Class A and B premises where the selected formulation is suitable
Class A and B protection where rated
Foam fire extinguishers: uses, colour and safety guidance
Learn how foam extinguishers cool solids and suppress suitable flammable-liquid fires, where they are commonly used and which hazards need a different agent.
Page summary
Foam extinguishers at a glance
The fire risk assessment should determine whether this extinguisher is appropriate, the fire rating required and where it should be positioned. Colour helps identification; it does not replace reading the label.
- Often rated for solid and liquid fires
- Forms a blanket over suitable liquid fuel
- Cream identification band
- Not for cooking-oil, gas or metal fires
Correct selection
What foam extinguishers can—and cannot—be used for
No single portable extinguisher is suitable for every fire. Use only equipment selected for the premises and only on the classes and conditions stated on its label.
- Deep-fat fryers and cooking oils
- Flammable gases
- Combustible metals
- Live electrical equipment unless the exact product has a documented dielectric test and instructions
- Flowing or three-dimensional liquid fires without specific assessment and trained use
How it controls fire
How a foam extinguisher works
Foam can cool the fuel and form a film or blanket across a suitable liquid surface, helping separate vapour from oxygen and reduce re-ignition. Its Class A performance also relies on the water content cooling solid material.
The blanket can be disrupted by poor technique, flowing fuel or incompatible substances. Foam formulations also differ, so legacy and replacement products should be identified, maintained and disposed of correctly by a competent provider.
Premises examples
Where this extinguisher may be considered
These are prompts for assessment, not ready-made specifications. Building use, quantities, people at risk and other protection can change the answer.
Workshops and maintenance areas
May suit combined solid and liquid hazards such as packaging and limited quantities of compatible fuels or paints.
Warehouses and industrial units
Can form part of protection where Class B stock is present, subject to quantities, storage, spill behaviour and site arrangements.
Garages and service premises
Potentially useful for some liquid-fuel risks, but gas cylinders, batteries, electrical equipment and running fuel can change the selection.
Offices and public premises
Sometimes specified for ordinary combustibles, though the need for Class B capability should be justified rather than assumed.
Before specifying equipment
Selection points that matter
Do not buy by colour or cylinder size alone. A competent selection considers the hazards, certified ratings, likely users, positioning and interaction with the emergency plan.
Liquid compatibility
Confirm the foam is suitable for the liquids present and the expected spill or container size. Some water-miscible liquids need specialist foam.
Environmental management
Identify the foam formulation, containment implications and disposal requirements. Replacement decisions should follow current product, environmental and waste guidance.
Electrical equipment
Never generalise from one product’s dielectric test. Check the exact marking and minimum distance, and avoid directing users towards an unsuitable agent.
Application technique
Effective use on a liquid surface can require controlled indirect application. Staff expected to use equipment need suitable instruction and training.
Life safety comes first
Portable extinguishers support escape; they do not make firefighting compulsory
Raise the alarm, begin the evacuation procedure and call 999. A person should only consider using an extinguisher if they have been instructed or trained, the fire is small, the correct unit is available, smoke is not affecting them and a clear escape route remains behind them. Never delay evacuation or take personal risk.
Inspection and servicing
Keep the provision usable and correctly specified
Routine checks should identify discharged, damaged, missing, obstructed or out-of-date equipment. Competent servicing should confirm condition, agent, rating, position, signage and records, while the fire risk assessment should be reviewed when hazards or layouts change.
BAFE’s SP101 scheme provides third-party certification for organisations that commission and maintain portable fire extinguishers. Certification can be useful evidence, but check that the provider’s current scope covers the work required.
Frequently asked questions
Foam extinguisher FAQs
What colour is a foam fire extinguisher?
A modern UK foam extinguisher normally has a red body with a cream identification band. Always also read the agent name and fire ratings on the label.
What fire classes can foam extinguishers cover?
They are commonly rated for Class A solid combustibles and Class B flammable liquids. Ratings vary, so confirm the classes and numeric performance shown on the particular extinguisher.
Can foam be used on electrical equipment?
Do not assume so. A particular foam extinguisher may have a documented dielectric test and minimum-distance instruction, but electricity remains a serious hazard and the exact unit’s marking must be followed.
Can foam be used on a chip-pan or commercial fryer fire?
No. High-temperature cooking oils and fats are Class F risks and normally require suitably rated wet-chemical or other specifically tested Class F equipment. Water-based foam can create a dangerous reaction.
Are all firefighting foams the same?
No. Formulations, liquid compatibility, environmental characteristics and ratings differ. A competent provider should identify existing units and select replacements for the actual hazard.
Sources and limitations
Guidance checked against authoritative UK sources
This is general information, not an extinguisher specification or instruction to fight a fire. The selection, number, rating and position of extinguishers depend on a suitable and sufficient fire risk assessment, recognised guidance, manufacturer instructions and the actual premises.