Types of fire extinguisher

1. OSHA Office of Training and Education 1
Exit Routes, Emergency Action
Plans, Fire Prevention Plans,
and Fire Protection

2. Fire Extinguisher
• A fire extinguisher is an active fire protection device
used to extinguish or control small fires, often in
emergency situations.
• Prevention is based on eliminating or minimizing one
of the components of the “Fire Triangle”.
OSHA Office of Training and Education 2

3. OSHA Office of Training and Education 3
Portable Fire Extinguishers
If portable fire extinguishers
are provided for employee
use, the employer must
mount, locate and identify
them so workers can access
them without subjecting
themselves to possible injury.
Blocked extinguisher

4. • Three things must be present at the same time to
produce fire:
• 1. Enough OXYGEN to sustain combustion
• 2. Enough HEAT to reach ignition temperature
• 3. Some FUEL or combustible material
• Together, they produce the CHEMICAL REACTION
that is fire.
• Take away any of these things and the fire will be
extinguished.
4

5. Fire Classifications
• Fires are classified according to the type of fuel that
is burning.
• If one use the wrong type of fire extinguisher on the
wrong class of fire, one might make matters worse.
• Its very important to understand the five different fire
(fuel) classifications...
OSHA Office of Training and Education 5

6. Fire Classifications
• Class A Fires: Ordinary combustibles such as wood
and paper.
• Class B Fires: Flammable and combustible liquids
and gases.
• Class C Fires: Energized electrical equipment.
• Class D Fires: Combustible metals.
• Class K Fires: Cooking Oils and Fats, Kitchen.
OSHA Office of Training and Education 6

7. OSHA Office of Training and Education 7
Extinguisher Classification
• Class A – ordinary combustibles (wood, cloth, paper)
• Class B – flammable liquids, gases, greases
• Class C – energized electrical equipment
• Class D – combustible metals
Letter classification given an extinguisher to designate
the class or classes of fire on which it will be effective.
A B C D
Ordinary
Combustibles
Combustible
Metals
Flammable
Liquids
Electrical
Equipment

8. Fire extinguishers
• There are two main types of fire extinguishers:
stored-pressure and cartridge-operated
• In stored pressure units, the expellant is stored in the
same chamber as the firefighting agent itself.
Depending on the agent used, different propellants
are used like nitrogen, air. Stored pressure fire
extinguishers are the most common type.
• Cartridge-operated extinguishers contain the
expellant gas in a separate cartridge that is
punctured prior to discharge, exposing the propellant
to the extinguishing agent. This type is not common.
OSHA Office of Training and Education 8

9. Types of fire extinguishers
• Different types of fire extinguishers are designed to
fight different classes of fire.
• The 3 most common types of fire extinguishers are:
1. Water (Air Pressurized Water)
2. Carbon Dioxide (CO2)
3. Dry Chemical (ABC, BC, DC)
4. Wet Chemical
OSHA Office of Training and Education 9

10. Water (Air Pressurized Water)
• Filled with ordinary tap water and pressurized air, they are
essentially large squirt guns.
• APW’s extinguish fire by taking away the “heat” element of
the Fire Triangle.
• APW’s are designed for Class A fires only: Wood, paper, cloth.
• It has the advantage of being inexpensive, harmless, and
relatively easy to clean up.
• Disadvantage: Freezes at 32°F (0°C).
• Load-stream extinguishers, wetting agents, or water mist can
be used. 10

11. Carbon Dioxide Fire Extinguishers
• CO2 cylinders are red. They range in size from 5 lbs
to 100 lbs or larger. On larger sizes, the horn will
be at the end of a long, flexible hose.
• The pressure in a CO2 extinguisher is so great, bits of dry ice
may shoot out of the horn!
• CO2’s are designed for Class B and C (Flammable Liquids
and Electrical Sources) fires only!
• Carbon dioxide is a non-flammable gas that takes away the
oxygen element of the fire triangle. Without oxygen, there is no
fire.
• CO2 is very cold as it comes out of the extinguisher, so it
cools the fuel as well.
11

12. • A CO2 may be ineffective in extinguishing a Class A
fire as it may not be able to displace enough oxygen
to successfully put the fire out or the high-pressure
cloud of gas can scatter burning materials.
• CO2 is not suitable for use on fires containing their
own oxygen source, metals or cooking media.
Although it can be rather successful on a person on
fire, its use should be avoided where possible as it
can cause frostbite and suffocation.
• Class A materials may also have tendency to re-
ignite.
OSHA Office of Training and Education 12

13. Dry Chemical (ABC) Fire
Extinguishers
• Dry chemical extinguishers put out fire by coating the fuel
with a thin layer of dust. This separates the fuel from the
oxygen in the air.
• The powder also works to interrupt the chemical reaction of
fire. These extinguishers are very effective at putting out fire.
• “ABC” fire extinguishers are filled with a fine yellow powder.
The greatest portion of this powder is composed of mono
ammonium phosphate. The extinguishers are pressurized
with nitrogen.
13

14. Dry chemical extinguishers
come in a variety of types...
• DC (for “Dry Chemical”)
• ABC (can be used on Class A, B, or C fires)
• BC (designed for use on Class B and C fires)
• Disadvantage: Chemicals are corrosive.
• Primary compounds:
• Sodium bicarbonate
• Potassium bicarbonate
• Urea-based potassium carbonate
• Potassium chloride
• Ammonium phosphate
OSHA Office of Training and Education 14

15. Wet Chemical
• Used for Class A, C,K fires.
• Extinguishes by cooling and forming a foam blanket
to prevent re-ignition.
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16. OSHA Office of Training and Education 16
Maintaining Portable Fire Extinguishers
• Must maintain in a fully charged and
operable condition
• Must keep in their designated places
at all times except during use
• Must conduct an annual maintenance
check
• Must record the annual maintenance
date and retain this record for one year
after the last entry or the life of the
shell, whichever is less

17. OSHA Office of Training and Education 17
Portable Fire Extinguisher
Training and Education
• Where portable fire extinguishers
have been provided for employee
use in the workplace, employees
must be provided with an
educational program on the:
 General principles of fire
extinguisher use
 Hazards of incipient
(beginning) stage fire fighting
• Employees designated to use
extinguishers must receive
instruction and hands-on practice
in the operation of equipment

18. OSHA Office of Training and Education 18
Summary
• There must be enough exits in the proper
arrangement for quick escape
• Exit routes must be marked, lighted, free of
obstructions, and locks must not be used to impede
or prevent escape
• An emergency action plan and a fire prevention plan
must be in place
• Fire extinguisher classes and numerical ratings help
a user understand its capabilities
• Fire extinguishers must be inspected, maintained
and employees must be trained in how to use them