Simply having fire extinguishers in a building is only half the job. What truly matters is whether they provide the appropriate performance for the specific fire risks present. This is where extinguishing units come into play. Together with the fire class, they make it possible to select the correct extinguisher—one capable of effectively tackling the potential fire hazard at its intended location.
Understanding the Label on a Fire Extinguisher
Every fire extinguisher tested according to European Standard EN 3 carries a performance rating consisting of a number and a letter—for example, 21A, 113B, or 75F.
- The Letter: The letter indicates the fire class for which the extinguisher is suitable:
- Class A: Solid, glowing materials (wood, paper, textiles)
- Class B: Flammable liquids or melting materials (petrol, oils, paints)
- Class C: Flammable gases (propane, natural gas)
- Class D: Combustible metals (magnesium, lithium — requires special extinguishers)
- Class F: Cooking fats and oils (typically deep-fat fryer fires). If multiple letters appear (e.g., AB or ABC), the extinguisher is suitable for several fire classes.
- The Number: The number quantifies the extinguisher’s performance within that fire class:
- For Class A, the number indicates the length (in decimeters) of a standardized wood stack that can be extinguished.
- For Class B, the number represents the quantity (in liters) of flammable liquid that can be extinguished.
These performance ratings determine the assigned extinguishing units, which are used to calculate the required fire protection equipment according to workplace safety regulations. For example: A 6-kg powder extinguisher for A, B, and C fires may correspond to 9 extinguishing units. A 6-liter foam extinguisher for A and B fires typically provides 6 extinguishing units. These values make direct performance comparisons possible.
How to Choose the Right Fire Extinguisher: A Practical Guide
Selecting the correct extinguisher is not only a regulatory requirement but also a matter of assessing fire risks at the specific location.
- Analyse the Fire Hazard Identify the primary fire risks: Predominantly solid combustibles (office, paper storage), flammable liquids (workshops, chemical facilities) or cooking fats and oils (commercial kitchens). The fire class you need depends on these risks.
- Select the Appropriate Extinguishing Agent
- Water extinguishers: Suitable for Class A fires. Minimal secondary damage
- Foam extinguishers: Suitable for Class A and B fires. Effective and low secondary damage. Ideal for offices, homes, hotels
- Powder extinguishers: Suitable for Class A, B, and C fires. Very high extinguishing performance. Significant secondary damage due to fine powder. Best for outdoor areas, garages, technical rooms.
- Carbon dioxide extinguishers. Suitable for Class B and C fires. Leave no residue. Use with caution in enclosed spaces (risk of suffocation). Ideal for server rooms, laboratories, or technical areas
- Wet chemical extinguishers (for fat fires). Designed specifically for Class F fires. Form a protective layer preventing re-ignition. Essential in commercial kitchens.
- Determine the Required Extinguishing Performance: Workplace regulations define: The number of extinguishing units required per floor area and risk category and the maximum travel distance to the next extinguisher (20 metres). Ensure that the total extinguishing units of the extinguishers you install meet or exceed these requirements.
- Correct Placement and Signage Fire extinguishers must be: Easily accessible, clearly visible, correctly marked and regularly inspected by trained personnel.
Choosing the right fire extinguisher—based on fire class and extinguishing performance—is a critical component of any fire safety plan. It ensures that in an emergency, the right equipment is available to tackle the fire effectively. Proper selection, placement, and maintenance significantly increase safety and can prevent serious property damage.
