Portable Fire Extinguishers: Classes and Selection
A clear, engineer-written guide to portable fire extinguishers — the fire classes, which extinguishing agent suits each fuel, and how extinguishers are sited and maintained.
Portable fire extinguishers are the first line of defence against a small, early-stage fire. Used correctly in the first moments, the right extinguisher can stop a fire before it grows; used wrongly, the wrong type can make a fire worse or cause electric shock. Matching the extinguisher to the kind of fire is therefore essential.
Fires are grouped into classes by the fuel that is burning, and each extinguishing agent works best on certain classes. This lesson explains the fire classes, the main extinguisher types and what they suit, and the basics of where extinguishers go and how they are kept ready.
How it works
Fire classes by fuel. Fires are classified by what is burning. Class A is ordinary combustibles (wood, paper, textiles); Class B is flammable liquids (petrol, oil, solvents); Class C is flammable gases; Class D is combustible metals; and Class F (called Class K in some regions) is cooking oils and fats. Fires involving live electrical equipment are treated as a special case because of the shock risk.
How extinguishing agents work. Each agent removes one or more sides of the fire triangle — fuel, heat, oxygen. Water and water-additive cool; foam smothers and cools liquid fires; dry powder interrupts the chemical reaction and covers a wide range of classes; carbon dioxide displaces oxygen and leaves no residue; and wet chemical reacts with hot cooking oil to form a sealing layer. The agent must match the fuel.
Matching extinguisher to fire. Water and foam suit Class A; foam, CO₂, and powder suit Class B; dry powder suits flammable gases (Class C); special powders suit metal fires (Class D); CO₂ and clean agents suit live electrical equipment without leaving residue; and wet chemical is made for cooking-oil fires (Class F/K). Multi-purpose ABC powder covers several classes, which is why it is common in general areas.
Siting and signage. Extinguishers are placed on escape routes and near specific hazards so the correct type is within a short travel distance of any fire. They are mounted where they are visible and easy to reach, clearly signed, and the type is chosen for the risks in that area — for example CO₂ near electrical equipment and wet chemical in commercial kitchens.
Maintenance and readiness. An extinguisher is only useful if it works. It must be kept charged, unobstructed, and in date, with regular inspection and periodic servicing by a competent person, and recharging or replacement after any use. Occupants should also know which extinguisher to use and how — a small fire is only fought if it is safe to do so, and never at the expense of escape.
Main types
In the UAE
- Portable extinguisher provision, type, siting, and maintenance in the UAE follow the UAE Fire & Life Safety Code of Practice and are inspected by Civil Defence (in Abu Dhabi, ADCD).
- Extinguishers must be listed/approved, correctly selected for each area’s risks (e.g. wet chemical in kitchens, CO₂ near electrical rooms), and clearly signed on escape routes.
- Regular inspection and periodic servicing by a competent provider are required, with records retained and units recharged or replaced after use.
How GPR applies this
As an Abu Dhabi MEP and fire contractor, GPR selects and installs portable fire extinguishers matched to each area’s risks — foam and ABC powder in general spaces, CO₂ near electrical equipment, and wet chemical in kitchens — sited on escape routes with clear signage. GPR coordinates the layout with the overall fire strategy, provides documentation for ADCD inspection, and can support ongoing inspection and servicing.
Frequently asked questions
What do the fire classes mean?
They group fires by fuel: Class A ordinary combustibles, Class B flammable liquids, Class C flammable gases, Class D combustible metals, and Class F/K cooking oils and fats, with live electrical equipment treated as a special case.
Which extinguisher should I use on an electrical fire?
A CO₂ or clean-agent extinguisher, because they displace oxygen and leave no residue without conducting electricity. Water and foam must not be used on live electrical equipment.
Why is the wrong extinguisher dangerous?
The wrong agent can spread the fire (for example water on a liquid or cooking-oil fire) or cause electric shock (water on live equipment), so the extinguisher must match the fuel.
What is ABC powder used for?
It is a multi-purpose dry powder effective on Class A, B, and flammable-gas fires, which makes it common in general areas, though it leaves a residue that can foul electronics.
How often do extinguishers need servicing?
They require regular inspection and periodic servicing by a competent person, must be kept charged and unobstructed, and should be recharged or replaced after any use, with records retained for the authority.