User Manual
Siemens Switzerland Ltd 27
Building Technologies Division
4.4.2. Fire extinguishers
Fire extinguishers are mobile or portable manual devices designed for preventing incipient stage fires from
getting out of control. The extinguishing agent is expelled under pressure. In some types of extinguisher the
agent is kept under constant pressure, while in others the pressure is generated by releasing a propellant gas at
the time that the extinguisher is activated.
Extinguishing agents include water, foam, carbon dioxide and powder. These substances function in different
ways and are suitable for different types of fires. Fires are categorized into five main fire classes A, B, C, D and F.
EN fire class Description
A
Solid materials
Solid materials subject to thermal decomposition which normally for
members.
Examples: wood, paper, leather, textiles and coal
B
Liquids
Liquids or materials which melt under heat and only create flames.
Examples: alcohol, oil, wax, resin, paraffin, petrol, paints, tar and acetone
C
Gases
Gaseous materials which are often stored under pressure.
Examples: hydrogen, natural gas, acetylene, methane, ethane, propane
and butane
D
Metals
Strongly ember-forming, combustible metals.
Examples: aluminum, magnesium, potassium, sodium, beryllium, lithium
and barium
F
Cooking oils
Combustible cooking oils and fats commonly found in commercial
kitchens.
Figure 4.3.3-1 Material fire classes
Notes:
1. In the European norms electrical fires are not considered to constitute a fire class on their own, as
electricity is a source of ignition that will feed the fire until removed.
2. The above table reflects the European classification system. Definitions used by regulatory bodies in
other parts of the world may show some minor differences. For example in the USA:
Cooking materials: Class K / Liquids + Gases: Class B / Electrical equipment: Class C
Extinguisher
types
Class of Fire
A B C D F
Solids Liquids Gases Metal Cooking oils
Water Yes No No No No
Foam Yes Yes No No No
ABC Powder Yes Yes Yes No No
Dry powder
(Metal Fires)
No No No Yes No
CO2 No Yes No No No
Wet chemical No No No No Yes
Figure 4.3.3-2 Fire extinguisher applications