Extinguishing Units: What You Need to Know About Fire Extinguisher Performance

Portable fire extinguishers are often the first line of defense in the event of a fire. However, their effectiveness is not determined simply by the weight of the extinguishing agent. This is where extinguishing units come into play. Extinguishing units are a standardized measurement that allows the performance of different fire extinguishers to be compared objectively and helps determine the required number for a building or facility. They are based on standardized testing according to European Standard EN 3 and are particularly important in Germany through the Technical Rules for Workplaces (ASR A2.2).

The Meaning of Extinguishing Units

An extinguishing unit is not a measurement of quantity, but a measure of how effectively a fire extinguisher can extinguish a defined test fire. Every fire extinguisher certified according to EN 3 receives a specific rating, consisting of a number and a letter (for example: 21A, 113B, 75F).

• The letter indicates the fire classification for which the extinguisher is suitable (A for solid combustibles, B for flammable liquids, F for cooking fats and oils, etc.).
• The number indicates the extinguisher’s performance within that fire class.
  • For Class A: the number represents the length, in decimeters, of a standardized wood stack that can be extinguished.
  • For Class B: the number represents the volume of flammable liquid, in liters, that can be extinguished.

Based on these ratings, each extinguisher is assigned a specific number of extinguishing units according to the allocation tables defined in German workplace safety regulations. For example, a fire extinguisher rated 21A / 113B typically corresponds to several extinguishing units for each fire class. It is important to note that you cannot add the extinguishing performance of extinguishers directly, but you can add their assigned extinguishing units to determine compliance with requirements.

Determining Requirements for Workplaces

The Technical Rules for Workplaces (ASR A2.2 “Measures Against Fires”) specify how many extinguishing units must be provided within a workplace. The required number depends on several factors:

• Size of the workplace: Larger areas require more extinguishing units.
• Level of fire risk: A distinction is made between normal, medium, and increased fire hazards. Higher fire risk requires more extinguishing units
• Type of combustible materials: The fire classes present (A, B, C, D, F) determine which extinguishers are needed.

As a general rule, each floor must have at least six extinguishing units, and the maximum distance to the nearest extinguisher should not exceed 20 meters. For precise calculations, the tables in ASR A2.2 must be consulted.

Practical Relevance for Building Operators

Understanding extinguishing units is essential for building owners and responsible persons. It ensures that fire extinguishers are not only present but also capable of extinguishing developing fires effectively.

Correct equipment based on extinguishing unit calculations significantly improves personal safety and helps prevent extensive property damage. When selecting and placing fire extinguishers, it is always advisable to rely on the expertise of fire protection professionals. The right number and type of extinguishers can make a decisive difference in an emergency.