In brief
The right extinguisher is chosen according to the burning material. Multi-purpose dry powder or water is used on class A solid fires; powder, CO₂ or foam on class B liquid fires; powder or CO₂ on class C gas fires; only metal fire powder on class D metal fires; and wet chemical extinguishers on class F oil fires. A wrong choice can make the fire bigger or cause electric shock or an explosion.
Fire classes: A, B, C, D and F
To choose correctly between types of fire extinguisher, you first need to know the burning material. The TS EN 2 standard divides fires into five classes according to the burning material, and the pictograms on extinguisher labels are printed according to these classes:
| Class | Burning material | Workplace examples |
|---|---|---|
| A | Solid, usually organic materials that leave embers | Wooden pallets, cardboard, fabric, yarn, paper, many plastics |
| B | Liquids and liquefiable solids | Thinner, paint, solvents, petrol, diesel, hydraulic oil, wax |
| C | Gases | LPG, natural gas, acetylene, hydrogen |
| D | Combustible metals | Aluminium and magnesium swarf or dust, sodium, lithium |
| F | Cooking oils | Oil in fryers and pans, frying vats in industrial kitchens |
There is no separate class for "electrical fire" in this table. Electricity is the source of the fire; the burning material is the cable insulation, the plastic in the panel or the dust around it. The real question is whether the extinguisher can be used safely on live equipment.
Types of fire extinguisher and how they extinguish
- Dry chemical powder extinguisher (ABC powder): Breaks the combustion chain chemically and covers the surface. Effective on classes A, B and C; the most common type in workplaces. Its drawback is that the fine powder spreads everywhere and leaves a residue on electronic equipment.
- BC powder extinguisher: Effective on liquid and gas fires, weak at extinguishing the embers of solid materials.
- Carbon dioxide (CO₂) extinguisher: Extinguishes by reducing oxygen in the area and leaves no residue. Suitable for electrical panels, server rooms and small liquid fires. Its effect drops quickly in the open air and in wind; with solids that leave embers, the fire can reignite.
- Foam fire extinguisher: Covers the surface of the burning liquid with a layer and cools it. Effective on class B liquid fires and class A.
- Water or water mist extinguisher: Extinguishes by cooling; for class A.
- Metal fire powder (class D): Smothers the burning metal, cutting off its contact with air. No other extinguisher can do this safely.
- Wet chemical extinguisher (class F): Forms a soapy layer on the oil surface and cools the oil. For industrial kitchens.
Which one for which fire? Matching table
Art. 99 of the Regulation on the Protection of Buildings from Fire requires the type of portable extinguisher to be determined according to the risks in the space and makes the following matching: for class A, primarily multi-purpose dry chemical powder or water; for class B, dry chemical powder, carbon dioxide or foam; for class C, dry chemical powder or carbon dioxide; for class D, primarily dry metal powder extinguishers. In places such as hospitals, care homes and nursery schools, water or clean gas extinguishers are preferred.
The table below is a general guide; the final decision is made according to the class pictograms on the extinguisher's label and the manufacturer's instructions for use. In class C gas fires, the first step is not to extinguish but to close the gas valve: if a flame is extinguished without cutting off the gas flow, the gas building up in the area can turn into a greater explosion risk.
| Extinguisher | A | B | C | D | F | Live equipment |
|---|---|---|---|---|---|---|
| ABC dry chemical powder | Suitable | Suitable | Suitable | Not suitable | Not suitable | Generally usable; leaves residue on electronics |
| CO₂ | Limited | Suitable | Suitable | Not suitable | Not suitable | Preferred |
| Foam | Suitable | Suitable | Not suitable | Not suitable | Not suitable unless F is on the label | Not used unless the label permits |
| Water | Suitable | Not suitable | Not suitable | Not suitable | Not suitable | Not used |
| Metal fire powder | Not suitable | Not suitable | Not suitable | Suitable | Not suitable | Check the label |
| Wet chemical | Check the label | Not suitable | Not suitable | Not suitable | Suitable | Not used |
How is an extinguisher label read?
As important as choosing the right extinguisher is understanding at a glance what you are holding. On the body of an extinguisher manufactured to the TS EN 3 standard, look for the following information:
- Class pictograms: Separate symbols for A, B, C, D or F. Do not use the extinguisher on a class without a symbol.
- Extinguishing performance: Expressions such as "13A" or "89B" show the size of the fire that can be extinguished in standard test fires. Two extinguishers of the same weight can have different performance; compare them by this value, not by weight.
- Use on live equipment: If there is no statement on this for water-based extinguishers, they are not used on energised equipment.
- Operating temperature range: Important for extinguishers kept in cold stores or on open sites.
- Pressure gauge: On stored-pressure powder and water extinguishers, the needle should be in the green zone. CO₂ extinguishers have no gauge; whether they are full is found by weighing.
- Service label: The date of the last check and refill and the details of the company that serviced it.
Looking at these six items in the monthly internal check takes a few minutes and lets you catch an extinguisher that has failed before the service date.
Consequences of choosing the wrong extinguisher: four workplace examples
Electrical panel
Tackling a live panel with a water or foam extinguisher exposes the user to the risk of electric shock. ABC powder puts out the fire but leaves a residue that is hard to clean on the contactors, drives and boards in the panel. The correct order is: if possible, cut the power at the main switch, tackle the panel with CO₂, and after using CO₂ in a small, enclosed electrical room, do not stay inside without ventilating the room.
Deep fryer and oil vat
Throwing water on burning oil is the most dangerous mistake: the water instantly vaporises under the oil and sprays the burning oil around. CO₂ seems to suppress the flame for a moment, but because the oil has not cooled, it can reignite shortly afterwards. The right choice is a class F wet chemical extinguisher; first cut off the heating and the gas. The regulation also requires automatic extinguishing systems to be installed in the hoods of kitchens serving more than 100 people at a time; factory canteens can fall within this scope.
Metal dust and swarf
In a fire where aluminium or magnesium swarf or dust is burning, water can react with the burning metal, making the fire bigger and causing an explosion. CO₂ is ineffective on metals such as magnesium and can feed the reaction. ABC powder cannot extinguish burning metal; when sprayed under pressure, it can scatter the swarf. In automotive supplier and metalworking workshops in Bursa, keeping metal fire powder in sections where aluminium machining or magnesium casting is done, and training the person who will use it, is a separate planning matter.
Solvent and paint store
In a thinner or paint fire, water spreads the burning liquid and makes the fire bigger. Dry chemical powder or foam is used. The regulation also makes it mandatory to keep wheeled extinguishers in warehouses.
Number, location and checking of extinguishers
Art. 99 of the Regulation on the Protection of Buildings from Fire sets the following rules:
- Number: According to the regulation's own fire hazard classification (not to be confused with the OHS hazard class), there is one 6 kg dry chemical powder extinguisher or equivalent gas extinguisher for every 500 m² of building construction area in low hazard class buildings, and for every 250 m² in medium and high hazard class buildings.
- Wheeled type: Wheeled extinguishers are also mandatory in car parks, warehouses and plant rooms.
- Location: The travel distance to an extinguisher is at most 25 metres. Extinguishers are not placed behind doors, in closed cabinets or in deep wall recesses; if they are in a place that cannot be seen, they are indicated with a photoluminescent sign.
- Mounting: For extinguishers heavier than 4 kg and lighter than 12 kg, the height above the floor does not exceed approximately 90 cm.
- Maintenance: Periodic checks and maintenance are carried out according to the TS ISO 11602-2 standard. Extinguishers undergo a general on-site check once a year, and at the end of the fourth year the extinguishing agent is renewed and a hydrostatic test is carried out. The company carrying out the maintenance must hold a refilling and service competence certificate.
Annex III of the Work Equipment Regulation also includes portable extinguishers in the list of periodic inspections to be carried out at least once a year, unless the standard sets a shorter period; details are in our article on work equipment periodic inspection intervals. Add the refill and check dates to the OHS calendar.
An extinguisher is useless without training
Even the right extinguisher is often wasted in the hands of someone who has never used one: the pin cannot be pulled, the hose is pointed in the wrong direction, the cylinder is emptied over the top of the flames. Art. 11 of Law No. 6331 requires the employer to assign a sufficient number of trained people for firefighting, to have training and drills carried out and to keep the teams ready at all times. We explained how many people the firefighting team should consist of in our guide on the emergency plan and support staff.
We deliver theoretical and hands-on fire training. Your employees try out different types of extinguisher on a controlled fire, and learn by seeing why electrical, oil and metal fires need to be treated differently. For details, see our fire training and emergency plan pages, and for risks specific to metalworking workshops, see our metal and machinery page.
Frequently Asked Questions
Which extinguisher is used on an electrical panel fire?
If possible, cut the power first. On a live panel, a CO₂ extinguisher is preferred; it leaves no residue and does not conduct electricity. Water and foam extinguishers are not used unless their label states that they can be used on live equipment.
Does an ABC powder extinguisher put out every fire?
No. It is effective on classes A, B and C, but is not suitable for class D metal fires and class F oil fires. If these risks are present, you need to keep special extinguishers.
Where is a CO2 extinguisher used?
It is suitable for electrical panels, server and IT rooms, laboratories and small liquid fires. It leaves no residue. Its effect drops in open areas and wind; after using it in small enclosed rooms, nobody should stay inside without ventilating the room.
When are fire extinguishers refilled and checked?
Under the Regulation on the Protection of Buildings from Fire, extinguishers undergo a general on-site check once a year; at the end of the fourth year, the extinguishing agent is renewed and a hydrostatic test is carried out. An extinguisher that has been used or has lost pressure is refilled without waiting.
Fire classes, choosing the right extinguisher, hands-on extinguishing in a safe open area and an evacuation drill, all in one training.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.