- Commercial deep-fat fryers and cooking-oil appliances
- Class F fires within the marked rating
- Class A materials only where the unit also carries that rating
- Commercial kitchens where its placement and rating match the appliances
Class F cooking-oil protection
Wet chemical fire extinguishers: uses, colour and safety guidance
Wet chemical extinguishers are designed for high-temperature cooking oils and fats. Learn how Class F provision fits commercial kitchens and why other common agents can be dangerous.
Page summary
Wet chemical 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.
- Designed for cooking oils and fats
- Cools and forms a sealing layer
- Normally identified by a yellow band
- Essential where the FRA identifies a significant fryer risk
Correct selection
What wet chemical 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.
- Flammable liquids outside the marked ratings
- Flammable gases
- Combustible metals
- Live electrical equipment unless the exact product documentation expressly permits the use
- Any fryer larger than the extinguisher’s tested Class F capability
How it controls fire
How a wet chemical extinguisher works
Wet chemical is discharged as a controlled spray that cools the burning oil. It reacts at the surface to form a soapy sealing layer, helping suppress vapour and reduce re-ignition.
Cooking oils can remain above their auto-ignition temperature. Switching off the heat source where safe and applying the agent correctly are therefore important. Throwing water onto a hot-fat fire can cause violent spread.
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.
Restaurants and commercial kitchens
Fryers, ranges and extraction arrangements should be assessed together, with suitably rated equipment accessible without approaching through the fire.
Pubs, hotels and event venues
Class F provision may be needed wherever catering includes significant oil or fat frying, including separate or temporary kitchens.
Takeaways and food production
High-use appliances, oil volume, cleaning, ductwork and staffing patterns can justify careful rating, siting and training.
Schools and care kitchens
The cooking process, supervision, evacuation needs and people expected to use equipment must inform selection.
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.
Fryer capacity
Match the extinguisher’s Class F rating to the oil volume and appliance arrangement. Do not use a headline extinguisher size as a substitute for the rating.
Access and escape
Position equipment so a user can reach it without moving towards the fire and can retain a safe exit route.
Kitchen systems
Coordinate portable extinguishers with appliance isolation, fire blankets, fixed suppression, extraction cleaning, alarms and the emergency plan.
Training
A controlled spray technique and safe shutdown matter. Staff should never take personal risk or attempt to tackle a developed fire.
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
Wet chemical extinguisher FAQs
What colour is a wet chemical extinguisher?
A modern UK wet chemical extinguisher normally has a red body with a yellow identification band. The label should also show its Class F rating.
What is a wet chemical extinguisher used for?
It is designed for Class F fires involving high-temperature cooking oils and fats, particularly commercial deep-fat fryers. Many units also have a Class A rating, but the label must be checked.
Why can’t water be used on a deep-fat fryer fire?
Water can sink into hot oil, turn rapidly to steam and violently eject burning oil. A suitably rated Class F extinguisher uses a controlled wet-chemical discharge designed for this hazard.
Do all commercial kitchens need wet chemical extinguishers?
The provision depends on the cooking equipment and fire risk assessment. A kitchen with a significant oil or fat fryer risk commonly needs Class F equipment; a kitchen without that hazard may need different protection.
Is a fire blanket enough for a commercial fryer?
A blanket may be suitable for small container fires and clothing, but should not automatically replace a correctly rated extinguisher for a commercial fryer. The appliance, oil capacity and kitchen arrangements must be assessed.
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.