Fire extinguishers are categorised based on the types of fires they are intended to handle. Various types are available, and choosing the correct one is crucial for effective fire protection. This guide explains the types and fire classification systems to help you select the right extinguisher in the event of a fire, whether at home, work, or construction sites.
Six Fire Classes
Before we get into the fire extinguishers in detail, it’s important to look at what materials are present in the area to be protected from fire. These can be divided into six fire classes involving different substances:
- Class A: Combustible carbon-based solids such as paper, wood, and textiles.
- Class B: Flammable liquids like paraffin, petrol, diesel, or oil (excluding cooking oil).
- Class C: Flammable gases such as butane, propane, or methane.
- Class D: Burning materials like aluminium, lithium, or magnesium.
- Class F: Fats and cooking oils.
Note: Class E is not used in fires involving electrical equipment; instead, the symbol of an electric spark is displayed. This is because electricity serves more as an ignition source than a fuel. Electrical fires often result from faulty wiring, frayed cables, broken appliances/tools, short circuits, overloading multi-adaptor plug sockets, hairdryers, extension leads, and similar issues.
Five Fire Extinguisher Types
There are six main types of fire extinguishers. Each is categorised into five classes based on the type of fuel involved, represented by a letter of the alphabet for easy identification (as mentioned above).
1. Water fire extinguishers
Water fire extinguishers are used on Class A fires. As the name suggests, these extinguishers use water as an extinguishing agent. Water has a cooling effect; when directed at the flames, it lowers the overall temperature and prevents the fire from burning further. They feature a white label or ID sign on their body marked “WATER” for easy identification.
2. Foam fire extinguishers
Foam fire extinguishers are suitable for both Class A and Class B fires. They can also be used on electrical fires, provided the extinguisher has passed the 35kV conductivity test. This test is an additional safety measure designed to protect users from potential electric shock if a foam extinguisher is accidentally used on an electrical fire.
To identify a foam fire extinguisher, look for a cream-coloured label on the body marked “FOAM.” There should also be an extinguisher ID sign nearby labelled "Foam Extinguisher.”
3. Dry powder fire extinguishers
Dry powder fire extinguishers are multi-purpose and can be used on Class A, B, and C fires, including those involving live electrical equipment. They work by coating the fuel with a thin layer of powder, which separates the fuel from the oxygen in the air. Moreover, the powder interrupts the chemical reaction that sustains the fire.
These extinguishers feature a blue label marked “POWDER” and an ID sign that reads “Powder Extinguisher.”
4. Carbon Dioxide (CO2) fire extinguishers
CO2 fire extinguishers are used for electrical fires and are often paired with foam extinguishers. Carbon dioxide is stored as a liquid in the extinguisher and turns into gas under pressure when the handle is squeezed. Unlike water and foam extinguishers, they don’t cool the fire, making them ineffective for fires involving flammable solids. Instead, they work by displacing the oxygen around the flames with carbon dioxide to suffocate the fire.
This type is identified by a black label marked “CO2” and an ID sign that reads “CO2 Extinguisher.” The nozzle ends also feature a distinctive black horn design.
5. Wet chemical fire extinguishers
Wet chemical fire extinguishers are used for Class A and F fires. They contain potassium, which creates a fine mist when sprayed. This mist reacts to form a soapy layer on the fire’s surface, cooling it and smothering the flames without spreading the burning oil.
For identification, these extinguishers have a yellow label marked “WET CHEMICAL” and an ID sign that reads “WET CHEMICAL EXTINGUISHER.” The hose is longer than that of other extinguishers and includes a lance attachment.
Choosing the correct type of fire extinguisher for each class of fire can be a matter of life and death. We hope this guide helps you make informed decisions and choose the appropriate extinguisher for any situation.
Explore our dependable Blaizgard fire protection products, including synergy alarms and evacuation alarms. For inquiries, contact us at hello@s-pgroup.com or call +44 (028) 9442 8611. SP Group is a construction supplier in the UK and Ireland.