Fire Extinguisher Class
Class A fire extinguisher is used for ordinary combustibles,
such as wood, paper, some plastics and textiles. This class
of fire requires the heat-absorbing effects of water or the
coating effects of certain dry chemicals.
Class B fire extinguisher is used for flammable liquid and
gas fires such as oil, gasoline, etc. These fire extinguishers
deprive the fire of oxygen and interrupt the fire chain by
inhibiting the release of combustible vapors.
Class C fire extinguisher is used on fires that involve live
electrical equipment which require the use of electrically
nonconductive extinguishing agents. (Once the electrical
equipment is deenergized, extinguishers for Class A or B
fires may be used.)
A Class D fire extinguisher is used on combustible metals
such as magnesium, titanium, sodium, etc., which require
an extinguishing medium that does not react with the
burning metal.
A Class K fire extinguisher is used on fires involving
cooking media (fats, grease, and oils) in commercial
cooking such as restaurants. These fire extinguishers
work on the principal of saponification. Saponification
takes place when alkaline mixtures such as potassium
acetate, potassium citrate or potassium carbonate are
applied to burning cooking oil or fat. The alkaline mixture
combined with the fatty acid create a soapy foam on the
surface which holds in the vapors and steam and
extinguishes the fire.
A Trash-Wood-Paper
B Liquids
C Electrical Equip
D Metals
K Cooking Media
Indicate Extinguisher Suitability
According to Class of Fire

per NFPA 10 Annex B
FIGURE B.1.1
2007 EDITION