Portable Fire Extinguisher
History & Basics
The information provided here is intended to be a general overview of portable fire
extinguishers. Specific or detailed information should be acquired from other sources.
History:
Water has always been used as an extinguishing agent and arguably vessels used to
carry water were the original portable fire extinguishers. The fire bucket at the
right is a late 1800’S or early 1900’s version. Prior to metal buckets wood and
leather was commonly used. Fire buckets such as the one in the picture had round
bottoms so they would not sit properly and therefore would not be taken and used
for other purposes.
Over the years numerous agents have been developed for fire extinguishing as well as several
different means to deploy them. An early agent was sodium bicarbonate (baking soda) and it
is still used today. In the late 1800’s metal tubes filled with sodium bicarbonate were common
portable fire extinguishers. They usually hung on a post or the wall with the ring on the cap
(lid). With the cap removed the sodium bicarbonate was sprinkled onto the fire. This
obviously required the user to be very close to the fire and therefore it was only suitable for
small fires. The red portion at the bottom of the label on the extinguisher pictured to the left
indicates it sold for $3 – a lot of money at that time.
The soda-acid extinguisher (pictured to the right) was invented in the late 1800’s. It
contained a sodium bicarbonate solution and a separate small container of acid. When the
extinguisher was inverted the acid and sodium bicarbonate solution mixed producing
carbon dioxide (CO2) gas that built pressure in the container and acted as the propellant gas.
A chemical foam extinguisher was invented in the early 1900’s in Russia. It looked and
worked like a soda-acid extinguisher but the design was slightly different. Like a soda-acid
extinguisher the main tank contained a solution of sodium bicarbonate in water. The inner
container - larger than that found in a soda-acid extinguisher - contained a solution of
Aluminum Sulphate. When the solutions were mixed by inverting the extinguisher, the two
liquids reacted to create foam and carbon dioxide gas. The gas was the propellant for the
foam. Liquorice-root extracts and similar compounds were used as additives to stabilize the
foam (the bubble-walls).
The Pyrene Manufacturing Company developed an extinguisher using carbontetrachloride (CTC) in the early 1900’s. CTC primarily worked by creating a dense,
oxygen-excluding blanket of fumes when exposed to fire. The extinguisher was a brass
container with a hand pump (picture to the right). It could be refilled after use through
a filling plug.
Carbon tetrachloride was also used in glass ball extinguishers
(picture to the left). These glass spheres filled with CTC were to
be thrown into a fire. Some were designed with a spring loaded
hammer that released and broke the glass when exposed to heat
– the first automatic extinguishing system. Carbon tetrachloride
was suitable for liquid and electrical fires and was commonly
used in commercial vehicles.
Carbon-tetrachloride was a very common extinguishing agent for many years but its
use stopped in the 1950’s because of its toxicity. Worse, when exposed to flame it
converts to phosgene gas - a chemical weapon used during WWI.
The carbon dioxide extinguisher was invented in the 1920’s for Bell Telephone. Bell
needed an extinguishing agent that was electrically non-conductive to be used for
extinguishing fires in telephone switchboards. The extinguisher developed (picture to
the right) was a steel cylinder with a wheel to open the valve at the top, a woven brass
discharge hose covered with cotton, and a cone shaped nozzle. It also had a wooden
grip area at the base of the nozzle to protect the operator’s hand from the cold
expanding CO2.
Carbon dioxide extinguishes fire by displacing oxygen. Though the carbon dioxide is
cold when discharged and freezes moisture in the air the cooling effect on most fires is
negligible.
In the 1920’s a dry chemical extinguisher was developed using sodium bicarbonate. It was a copper cylinder
containing the sodium bicarbonate and an internal CO2 cartridge. A wheel valve on the top was used to
puncture the CO2 cartridge. This was the first cartridge pressure dry chemical extinguisher available and was
primary used in industrial facilities. In the 1950’s small dry chemical fire extinguishers for home use were
introduced.
Multi-purpose (A, B, C) dry chemical became available in the 1950’s followed by Super-K in the
early 1960’s and Purple-K in the late 1960’s.
In the 1970’s, Halon 1211 and Halon 1301 became common primarily for use in electronics and
computer facilities. Both work by inhibiting the chain reaction of the fire. Halon is no longer
common in Canada because of concerns about the impact it has on the environment, in
particular on the ozone layer of our atmosphere.
A modern portable fire extinguisher such as the one pictured to the left is a device to be used
to extinguish or control small fires in emergency situations. It is not intended for use on a fire
that requires expertise or training to safely fight. Typically, a fire extinguisher is a hand-held
vessel containing an agent which can be discharged to extinguish the fire.
There are two main types of portable fire extinguishers - stored pressure and cartridge-pressure operated.
Stored pressure fire extinguishers have the propellant – the pressurized gas that
forces the agent out when the trigger is activated - stored in the same chamber as the
extinguishing agent itself. Depending on the agent used, different propellants are
used. Dry chemical extinguishers typically use nitrogen as a propellant; water and
foam extinguishers typically use air. Stored pressure fire extinguishers are the most
common type.
Stored pressure extinguishers are easily identified by the pressure
gauge found on the handle / trigger assembly at the top.
Cartridge-operated extinguishers contain the propellant gas in a separate cartridge
that is punctured prior to discharge, exposing the propellant to the extinguishing
agent. This type is not as common and is used primarily in high risk areas such as
industrial facilities.
These extinguishers generally use compressed carbon dioxide rather than nitrogen
as the propellant. Cartridge operated extinguishers are available in dry chemical
and dry powder types primarily.
Discharge Hose
Gas Cartridge
Portable fire extinguishers are also available in two styles dependant on
the their size and weight - handheld and cart-mounted more commonly
referred to as wheeled extinguishers. Handheld extinguishers typically
weigh from 0.5 to 14kgs (1 to 30lbs.). Cart-mounted units typically weigh
23kgs (50lbs.) or more. These wheeled models are most commonly found
at construction sites, airports runways, heliports, as well as docks and
marinas.
Fire Extinguisher Appearance:
It is difficult to recognize what extinguishing agent is used in a portable fire extinguisher by
appearance with two exceptions;
 CO2 fire extinguishers can be recognized by the cone shape discharge nozzle and the
heavy steel cylinder
 pressure water extinguishers are very commonly stainless steal or chrome vessels.
By comparison dry chemical extinguishers
 may or may not have a discharge hose
 may be stored pressure or cartridge pressure
 may have the discharge valve at the top of the extinguisher or
end of the discharge hose
 the carrying handle may be part of the discharge valve assembly
at the top of the extinguisher or may be on the side
 the extinguisher may be chrome or painted - there is no
standard or specified color though red and white are common.
Fire Extinguisher Rating / Classification:
Portable fire extinguishers are rated and classified by the type of fire (fuel) they are suitable for and the size of
the fire.
Class ‘A’ – the fire fuel is an ordinary combustible material such as wood, paper, cloth, rubber products,
plastics and similar materials.
Class ‘B’ – the fire fuel is a flammable or combustible liquid or gas such as gasoline, alcohol, diesel fuel, motor
oil, benzene, liquefied petroleum gas and similar products.
Class ‘C’ – the fire fuel is energized with electricity. The material actually burning will be a Class A, B and/or D
fuel energized with electricity. For example, in a transformer fire it is the oil in the transformer that is burning
but the transformer is energized with electricity.
Class ‘D’ – the fire fuel is a combustible metal such as magnesium.
The classification of the extinguisher will be displayed on the label using the letters and very often with
symbols.
A triangle is the symbol for Class ‘A’ fuels.
A square is the symbol for Class ‘B’ fuels.
A circle is the symbol for fuels energized with
electricity.
A star shape is the symbol for Class ‘D’ fuels.
Colours are also used on some labels as illustrated above.
In addition modern fire extinguishers may use pictographs to show the class of fire an extinguisher is suitable
for use on.
Class A
Class B
Class C
A typical found on a portable fire extinguisher is illustrated to the right.
This example indicates the extinguisher is suitable for use on Class A
ordinary combustible fuels but NOT suitable for Class B fuel fires
or Class C fires – those energized with electricity.
Note: in recent years cooking oil/fat fuelled fires have been designated with the letter ‘K’. Agents specifically
designed for kitchen fires have been developed.
Chemical Extinguishing Agents:
Some chemical fire extinguishing agents developed are distributed under product names specific to the
manufacturer and in some cases these names have become commonly applied to all similar products
produced by different manufacturers – similar heavy rescue tools being referred to as ‘Jaws of Life’ or snow
mobiles generally referred to as ‘Ski-Dos’.
Sodium bicarbonate,
 suitable for class B and C fires -it was the first of the dry chemical agents developed
 interrupts the fire's chemical reaction
 was very common in commercial kitchens fixed extinguishing systems before the development of wet
chemical agents - it is much less effective than new wet chemical agents for class K fires
 less effective than Purple-K for class B fires
 is ineffective on class A fires
 white or blue color.
Mono-ammonium phosphate
 commonly referred to as "multipurpose" or "A, B. C" dry chemical
 suitable for class A, B, and C fires
 class A rating from the agent's ability to melt and flow at 177 °C (350 °F) to smother the fire
 more corrosive than other dry chemical agents and not recommended for electronics or computers
 yellow in color.
Potassium bicarbonate
 commonly referred to as Purple-K
 suitable for class B and C fires
 approximately two times more effective on class B fires than sodium bicarbonate
 violet in color.
Potassium bicarbonate & Urea Complex
 also known as Monnex or Powerex
 suitable for Class B and C fires.
 more effective than all other powders
 grey in color.
Potassium Chloride,
 also known as Super-K
 suitable for Class B and C fires
 developed to create a high efficiency, protein-foam compatible with dry chemical.
 quite corrosive
 white in color.
Fire Extinguisher Maintenance:
The Ontario Fire Code requires that fire extinguishers in all buildings excluding private homes be serviced and
inspected by a qualified service company annually. In addition the fire extinguisher is to be inspected at least
once a month. This is often done by building staff. At the time of annual service, a tag is placed on the
extinguisher to indicate the type of service perform (annual service, recharge, hydrostatic testing, new fire
extinguisher) and date of service. The tag is often designed with spaces to record monthly inspections.