Introduction.
Before you need to use a fire extinguisher read the label to make
sure you fully understand the type of fire extinguisher it is. Also
the type of fires it is appropriate and safe to use on. Water and
foam based extinguishers should not be used on fires involving an
electrical hazard, unless the power supply has been isolated, this
is because the operator may receive a fatal electric shock. Before
you can operate most extinguishers you are required to remove the
safety pin, the only exceptions are hose reels, fire blankets and
fire buckets. With hose reels you may have open a water valve before
it can be used. Make sure before you tackle a fire you are between
the fire and exit or escape route.
Index
Water Extinguisher
 |
Red |
| Best For |
| Fires involving organic solid materials
such as wood, cloth, paper, plastics, Coal etc. |
| Danger |
| Do not use on burning fat or oil or on electrical appliances
|
| How to Use |
| Point the jet at the base of the flames and keep it moving
across the area of the fire. Ensure that all areas of the fire
are out. |
| How it Works |
| Water has a great effect on cooling the fuel surfaces and
thereby reducing the pyrolysis rate of the fuel |
return
Water Spray Extinguisher
|
 |
Red |
| Best For |
| Fires involving organic solid materials
such as wood, cloth, paper, plastics, Coal etc. Size for size,
it offers up to 300% more fire fighting capability than traditional
jet type water fire extinguishers. Available in 3 and 6 litres. |
| Danger |
| Do not use on burning fat or oil or on electrical appliances
|
| How to Use |
| Point the jet at the base of the flames and keep it moving
across the area of the fire. Ensure that all areas of the fire
are out. |
| How it Works |
Water has a great effect on cooling the fuel surfaces and
thereby reducing the pyrolysis rate of the fuel. Instead of
a jet nozzel a spray nozzel is used, with a higher pressure,
which creates a fine spray . This allows for a given quantity
of water to have a considerable increase in the surface area
presented to the fire. This makes extinguishing more efficient
by more rapid extraction of heat, formation of steam etc.
They can also contain surfactants which help the water penetrate
deep into the burning material which increase the effectiveness
of the extinguisher.
|
|
Dry Powder Extinguisher. (Multi-Purpose)
 |
Blue |
| Best For |
| Can be used on fires involving organic solids, liquids such
as grease, fats, oil, paint, petrol,etc
but not on chip or fat pan fires. |
| Danger |
| Safe on live electrical equipment, although does not penetrate
the spaces in equipment easily and the fire may re-ignite. This
type of extinguisher does not cool the fire very well and care
should be taken that the fire does not flare up again. Smoldering
material in deep seated fires such as upholstery or bedding
can cause the fire to start up again. Do not use on domestic
chip or fat pan fires. |
| How to Use |
| Point the jet or discharge horn at the base of the flames
and, with a rapid sweeping motion, drive the fire towards the
far edge until all the flames are out. If the extinguisher has
a shut-off control wait until the air clears and if you can
still see the flames, attack the fire again. |
| How it Works |
| Similarly to almost all extinguishing agents the powders acts
as a thermal ballast making the flames too cool for the chemical
reactions to continue. Some powders also provide a minor chemical
inhibition, although this effect is relatively weak. These powders
thus provide rapid knockdown of flame fronts, but may not keep
the fire suppressed. |
|
Dry Powder Extinguisher.(Standard)
|
Blue |
| Best For |
| Liquids such as grease, fats, oil, paint, petrol etc but not on domestic chip or fat pan fires. |
| Danger |
| Safe on live electrical equipment, although does not penetrate
the spaces in equipment easily and the fire may re-ignite. This
type of extinguisher does not cool the fire very well and care
should be taken that the fire does not re-ignite. Do not use
on domestic chip or fat pan fires. |
| How to Use |
| Point the jet or discharge horn at the base of the flames
and, with a rapid sweeping motion, drive the fire towards the
far edge until all the flames are out. If the extinguisher has
a shut-off control wait until the air clears and if you can
still see the flames, attack the fire again. |
| How it Works |
| Similarly to almost all extinguishing agents the powders acts
as a thermal ballast making the flames too cool for the chemical
reactions to continue. Some powders also provide a minor chemical
inhibition, although this effect is relatively weak. These powders
thus provide rapid knockdown of flame fronts, but may not keep
the fire suppressed. |
|
Dry Powder
Extinguisher.(Special Powders)
 |
Blue |
| Best For |
This specialist powder extinguishers are designed to tackle
fires involving combustible metals such as lithium, magnesium,
sodium or aluminium when in the form of swarf or powder.
There are three special powders based on graphite, copper
and sodium chloride.
|
| Danger |
| Do not allow water to come in contact with the
burning metal and the powder must be gently applied. Sodium
Chloride is not recommended for Lithium. |
| How to Use |
| The lance enables the user to tackle fire at a safe distance
and the low velocity applicator to reduce the energy of the
jet allowing the powder to gently smother the surface of the
burning material thus avoiding scattering of high temperature
particles and stimulating the formation of a crust. The method
of application is completely different from a standard extinguisher
and user training is required. They are not suitable for use
on live electrical fires. |
| How it Works |
| This extinguisher works by forming a crust which insulates
the metal to prevent access to other combustible material nearby
and smothering the fire to prevent oxygen from the atmosphere
reacting with the metal |
|
Foam Extinguisher. (AFFF)
 |
Cream (Aqueous film-forming foam) (multi-purpose) |
| Best For |
| Fires involving solids. Liquids such as grease, fats, oil,
paint, petrol,etc but not on domestic
chip or fat pan fires. Can be used on class A fires but
not recommended. |
| Danger |
| Do not use on domestic chip or fat pan fires. |
| How to Use |
| For fires involving solids, point the jet at the base of the
flames and keep it moving across the area of the fire. Ensure
that all areas of the fire are out. For fire involving liquids,
do not aim the jet straight into the liquid. Where the liquid
on fire is in a container, point the jet at the inside edge
of the container or on a nearby surface above the burning liquid.
Allow the foam to build up and flow across the liquid. |
| How it Works |
| They are mainly water based, with a foaming agent so that
the foam can float on top of the burning liquid and break the
interaction between the flames and the fuel surface. |
|
Foam Extinguisher.(Standard)
|
Cream |
| Best For |
| Fires involving solids. Liquids such as grease, fats, oil,
paint, petrol,etc but not on domestic
chip or fat pan fires. Can be used on class A fires but
not recommended. Less effective than AFFF foam |
| Danger |
| Check manufacturer's instructions for suitability of use
on other fires involving liquids. These extinguishers are generally
not recommended for home use. |
| How to Use |
| Do not aim jet straight into the liquid. Where the liquid
on fire is in a container, point the jet at the inside edge
of the container or on a nearby surface above the burning liquid.
Allow the foam to build up and flow across the liquid. |
| Howit Works |
| These are mainly water based, with a foaming agent so that
the foam can float on top of the burning liquid and break the
interaction between the flames and the fuel surface. |
|
Carbon Di-Oxide Extinguisher.
 |
BLACK
|
| Best For |
| Live electrical equipment when it is not possible to isolate
the electric supply and flammable liquids such as grease, fats,
oil paint, petrol etc. but not on domestic
chip or fat pan fires. |
| Danger |
| Do not use on domestic chip or fat pan fires. This type of
extinguisher does not cool the fire very well and you need to
watch that the fire does not start up again. Fumes from CO2
extinguishers can be harmful if used in confined spaces: ventilate
the area as soon as the fire has been controlled. |
| How to Use |
| The discharge horn should be directed at the base of the flames
and the jet kept moving across the area of the fire. |
| How it Works |
| Carbon dioxide extinguisher works on classes B and C and works
by suffocating the fire. Carbon dioxide will not burn and displaces
air. |
|
Wet Chemical
 |
Canary Yellow |
| Best For |
| The specialist wet chemical extinguishers are ideal for Class
F fires, involving cooking oils and fats, such as lard, olive
oil, sunflower oil, maize oil and butter. |
| Danger |
Check manufacturer's instructions for suitability of use.
These extinguishers are not recommended for class B fires
and home use.
|
| How to Use |
| Apply the wet chemical using the extended applicator in slow
circular movements, which give a gentle, yet highly effective
application. Apply the fine spray onto the burning fat until
the surface of the burning cooking oil changes into a soapy
like substance, this then prevents re-ignition. The gentle application
helps prevent hot oil splashing onto the user. |
| How it Works |
| Most class F extinguishers contain a solution of potassium
acetate, sometimes with some potassium citrate or potassium
bicarbonate. The extinguishers spray the agent out as a fine
mist. The mist acts to cool the flame front, while the potassium
salts saponify the surface of the burning cooking oil, producing
a layer of foam over the surface. This solution thus provides
a similar blanketing effect to a foam extinguisher, but with
a greater cooling effect. The saponification only works on animal
fats and vegetable oils, so class F extinguishers cannot be
used for class B fires. The misting also helps to prevent splashing
the blazing oil. Tests have established that a 6 litre extinguisher
is capable of extinguishing a fire in a 75 litre capacity deep
fat fryer. The extinguisher is easy to use producing a gentle
but highly effective spray. |
|
Fire Blanket
 |
Fire Blanket Fire blankets are made of fire resistant
materials. They are particularly useful for smothering flammable
liquid fires or for wrapping round a person whose clothing is
on fire. Fire blankets conforming to British Standard BS EN
1869 : 1997 are suitable for use in the home BS 7944 : 1999
is suitable for industrial use. These will be marked to show
whether they should be thrown away after use or used again after
cleaning in accordance with the manufacturers instructions.
|
| Best For |
| Fires involving both solids and liquids. Particularly good
for small fires in clothing and for domestic or commercial chip
and fat pan fires provided the blanket
completely covers the fire. |
| Danger |
| If the blanket does not completely cover the fire, it will
not be able to extinguished the fire. |
| How to Use |
| Place carefully over the fire. Keep your hands shielded from
the fire. Do not waft the fire towards you. |
| How it Works |
| Smothers the fireand prevent oxygen getting to the fire. |
|
Hose Reel
 |
Hose Reel |
| Best For |
| Fires involving organic solid materials
such as wood, cloth, paper, plastics, coal etc. |
| Danger |
| Do not use on burning fat or oil or on electrical appliances
before the electric supply has been isolated. |
| How to Use |
| Point the jet at the base of the flames and keep it moving
across the area of the fire. Ensure that all areas of the fire
are out. |
| How it Works |
| Water has a great effect on cooling the fuel surfaces and
thereby reducing the pyrolysis rate of the fuel |
|
Fire Buckets
 |
A simple bucket of water can be used on Class "A" type of
fires either to supplement a water extinguisher or as a first
attack if an extinguisher is not immediately available. It also
can be filled with dry sand and used as an absorbing agent or
to dam a flow of flammable liquid. They do have serious disadvantages
as they are often misused, left empty or allowed to be used
as a refuse container. |
| Best For |
| Wood, Cloth, Paper, Plastics, Coal etc.Fires involving solids
|
| Danger |
| Do not use on burning fat or oil or on electrical appliances
before the electric supply has been isolated. |
| How to Use |
| Throw at the base of the flames and keep it moving across
the area of the fire. Ensure that all areas of the fire are
out. |
| How it Works |
| Water has a great effect on cooling the fuel surfaces and
thereby reducing the pyrolysis rate of the fuel |
|
Extinguishing
Agents
Water
Water is the most common for class A fires and is quite effective
as one would imagine. Water has a great effect on cooling the fuel
surfaces and thereby reducing the pyrolysis rate of the fuel. The
gaseous effect is minor for these extinguishers, but water fog nozzles
used by fire brigades creates water droplets small enough to be
able to extinguish flaming gases as well. The smaller the droplets,
the greater the effect on flaming gases. With this in mind water
spray extinguishers have bee developed, one example is the Hydro
spray by Chubb. The Hydro spray Elite was developed in 1997 as a
direct response to customer needs. It was felt that the while traditional
9 litre water extinguishers are very effective on class A fires
made up of woods, solids or materials, a smaller, lighter version
would be much easier for some people to use. Chubb developed the
Hydro spray Elite. This 3 litre product is able to achieve the same
fire ratings as a 9 litre water extinguisher, in a size that makes
it easier for anyone to lift and manoeuvre.The unique nozzle that
separates the water particles making it safe (as per the 35kV test)
if it is accidentally used on an electrical fire.
In the past water based extinguishers also contain traces of other
chemicals to prevent the extinguisher rusting but are now lined
with plastic. Some also contain surfactants which help the water
penetrate deep into the burning material and cling better to steep
surfaces this is know as wet water.
Water may or may not help extinguishing class B fires it depends
on whether or not the liquid's molecules are polar molecules. If
the liquid that is burning has polar molecules, such as alcohol,
there won't be any problem. If the liquid is non polar, such as
large hydrocarbons, like petroleum, the water will sink through
the oil until it reaches the heat layer and then be immediately
converted to steam ejecting the burning contents in a violent eruption,
known as a boil over. Alternately as water being heavier than oil
it will sink to the bottom and replace the oil until the flaming
oil flows over the edge of the container thus spreading the fire;
this is known as a slop over. This is why you should never use water
on oil fires.
Similarly, water sprayed on an electrical fire will probably cause
the operator to receive an electric shock. However, if the power
can be reliably disconnected, clean water will actually cause less
damage to electrical equipment than will either foam or dry powders.
Special spray nozzles, equipped with tiny rotating devices called
spiracles will replace the continuous water jet with a succession
of droplets, greatly increasing the resistance of the jet. These
shall however be used by skilled personnel, since improper handling
of the nozzle may restore continuity of the water jet.
Foams
 Foams
are commonly used on class B fires, and are also effective on class
A fires. These are mainly water based, with a foaming agent so that
the foam can float on top of the burning liquid and break the interaction
between the flames and the fuel surface. Ordinary foams are designed
to work on non polar flammable liquids such as petrol, but may break
down too quickly in polar liquids such as alcohol or glycol. Facilities
which handle large amounts of flammable polar liquids use specialised
"alcohol resistant foam" instead. Alcohol foams must be
gently poured across the burning liquid. If the fire cannot be approached
closely enough to do this, they should be sprayed onto an adjacent
solid surface so that they run gently onto the burning liquid. Ordinary
foams work better if poured but it is not critical.
Protein foam was used for fire suppression in aviation crashes
until the 1960s development of "light water", also known
as "Aqueous Film-Forming Foam" (or AFFF). Carbon dioxide
(later sodium bicarbonate) extinguishers were used to knock down
the flames and foam used to prevent re-ignition of the fuel fumes.
"Foaming the runway" can reduce friction and sparks in
a crash landing, and protein foam continued to be used for that
purpose, although FAA regulations prohibited reliance upon its use
for suppression.
Dry Powder
Principally there are two types of dry powder extinguishers in use,
they are BC and ABC.
Class BC dry powder is either sodium bicarbonate or potassium bicarbonate,
finely powdered and propelled by carbon dioxide or nitrogen. Similarly
to almost all extinguishing agents the powder acts as a thermal
ballast and makes the flames too cool for the chemical reactions
to continue. Some powders also provide a minor chemical inhibition,
although this effect is relatively weak. These powders thus provide
rapid knockdown of flame fronts, but may not keep the fire suppressed.
Consequently, they are often used in conjunction with foam for attacking
large class B fires. BC Powder has a slight saponification effect
on cooking oils & fats due to its alkalinity and was used for
kitchens prior to the invention of Wet Chemical extinguishers. Where
an extremely fast knockdown is required potassium bicarbonate (Purple
K) extinguishers are used. A particular blend also containing urea
(Monnex) decrepitates upon exposure to heat increasing the surface
area of the powder particles and providing very rapid knockdown.
Sodium bicarbonate powders, unless specially treated, are not compatible
with Foams. Purple-K, Monnex and ABC Powders are generally less
damaging, and often are used with AFFF & FFFP, but compatibility
must be borne in mind where powder and foam are used together and
a higher application rate of foam allowed for.
Class ABC Powders are mixtures of ammonium phosphate and ammonium
sulphate, ground to selected particle sizes and treated with flow
promoting and moisture repellent additives. In addition to the particle
surface extinguishing effect, ABC powders have low melting/decomposition
points in the order of 150°C to 180°C. When these powders
are applied to hot and smouldering surfaces, the particles fuse
and swell to form a barrier which excludes oxygen and thereby completes
the extinguishing process and prevents re-ignition. They are acidic
in nature and are effective on Class A (flammable solids), Class
B (flammable liquid/liquefiable solids) and Class C (flammable gas)
fires. They are electrically non-conductive; however it is less
effective against three dimensional class A fires, or those with
a complex or porous structure. Foams or water are better in those
cases. Most dry powder extinguishers in service, except aerosols,
are ABC Powder. Different blends are available, the more ammonium
phosphate, the more effective it is. Powder, specifically ABC powder
is not permitted in or near aircraft as it can damage the metal
superstructure.
Dry powders can also be used on electrical fires, but provide a
significant cleanup and corrosion problem that is likely to make,
especially sensitive electronics and electrical equipment unsalvageable.
Although modern powders are non-toxic, the discharge of a powder
extinguisher in a confined space can cause a sudden reduction of
visibility which may temporarily jeopardize escape, rescue or other
emergency action. For this reason water-based extinguishers are
to be preferred in hospitals, old people's homes and hotels. Powder
extinguishers are prohibited to be used in PSV's and minibuses by
UK statute law for the above reason.
When used on class B fires, the powder must extinguish the whole
fire area in an uninterrupted application or flashback will occur,
unlike foam there is no physical barrier, it's all or nothing. The
lack of a securing blanket means there is a re-ignition risk. Also
powder has no cooling properties, one of the reasons it is ineffective
against class F fires, although it can extinguish the flame, the
heat of the fat will cause immediate flashback.
There were available powders designed for fires in flammable metals
and three main types in use were, Sodium Chloride for fires involving
alkali metals such as sodium and potassium, also zirconium, uranium
and powdered aluminium which extinguished metal fire by fusing to
form a crust. This excludes oxygen from the surface of the molten
metal and a carbonaceous rafting agent prevents the powder from
sinking into the surface of molten metal. A copper extinguishing
agent specially developed by the U.S. Navy for fighting lithium
and lithium alloy fires. The copper compound smothers the fire and
provides an excellent heat sink for dissipating heat. Copper powder
has been found to be superior to all other known fire extinguishing
agents for lithium. Finally Ternary Eutectic Chloride (TEC), developed
by UKAEA for uranium fires, which works similarly to Sodium Chloride
but it, is extremely toxic.
Wet potassium salts (Wet Chemical)
 Most
class F extinguishers contain a solution of potassium acetate, sometimes
with some potassium citrate or potassium bicarbonate. The extinguishers
spray the agent out as a fine mist. The mist acts to cool the flame
front, while the potassium salts saponify the surface of the burning
cooking oil, producing a layer of foam over the surface. This solution
thus provides a similar blanketing effect to a foam extinguisher,
but with a greater cooling effect. The saponification only works
on animal fats and vegetable oils, so class F extinguishers cannot
be used for class B fires. The misting also helps to prevent splashing
the blazing oil.
Note: Saponify is a chemistry term which means to become converted
into soap by being hydrolyzed into an acid and alcohol as a result
of oil or fat being treated with an alkali.
Carbon dioxide
 Carbon
dioxide extinguisher (CO2) works on classes
B and C and works by suffocating the fire. Carbon dioxide will not
burn and displaces air. Carbon dioxide can be used on electrical
fires because, being a gas, it does not leave residues which might
further harm the damaged equipment. Carbon dioxide can also be used
on class A fires when it is important to avoid water damage, but
in this application the gas concentration must usually be maintained
longer than is possible with a hand-held extinguisher. Carbon dioxide
has a discharge horn on the end of the hose which slows down the
jet of gas and prevents air being entrained. Due to the carbon dioxide
being expelled from an extinguisher, the horn becomes extreme cold
and should not be touched.
Halons
In the UK and Europe halon are illegal, except for certain specific
aircraft and law enforcement uses. This appears to be at least partially
in response to the Montreal Protocol and effort by the United Nations
Environment Programme (UNEP) to combat release of quantities of
harmful chemicals into the atmosphere.
Halon fire extinguishers are still legal in America and are very
versatile extinguishers. They will extinguish most types of fire
except class D & F and are highly effective even at quite low
concentrations (less than 5%). Halon is a poor extinguisher for
Class A fires, a nine pound Halon extinguisher only receives a 1-A
rating and tends to be easily deflected by the wind. They are the
only fire extinguishing agents that are quite suitable for discharge
in aircraft as other materials pose a corrosion hazard to the aircraft.
The major extinguishing effect is by disturbing the thermal balance
of the flame, and to a small extent by inhibiting the chemical reaction
of the fire. Halons are chlorofluorocarbons which cause damage to
the ozone layer and are being phased out for more environmentally-friendly
alternatives.
Halon extinguishers were used widely in vehicles and computer suites.
It is mildly toxic in confined spaces, but to a far less extent
than its predecessors such as carbon tetrachloride, chlorobromomethane
and methyl bromide.
Phosphorous tribromide
Like Halon, phosphorous tribromide interferes with the chemical
reaction of the flame, marketed under the brand name PhostrEx. PhostrEx
is a liquid which needs a propellant, such as compressed nitrogen
and/or helium, to disperse onto a fire. As a fire extinguisher PhostrEx
is much more potent than Halon making it particularly appealing
for aviation use as a lightweight substitute. Unlike Halon, PhostrEx
reacts quickly with atmospheric moisture to break down into phosphorus
acid and hydrogen bromide, neither of which harms the earth's ozone
layer. High concentrations of PhostrEx can cause skin blistering
and eye irritation, but since so little is needed to put out flames
this problem is not a significant risk, especially in applications
where dispersal is confined within an engine compartment. Any skin
or eye contact with PhostrEx should be rinsed with ordinary water
as soon as practical. PhostrEx is not especially corrosive to metals,
although it can tarnish some. The U.S. EPA and FAA both approved
PhostrEx, and the substance will find its first major use in Eclipse
Aviation's jet aircraft as an engine fire suppression system.
Fluorocarbons
Recently, DuPont has begun marketing several nearly saturated
fluorocarbons under the trademarks FE-13, FE-25, FE-36, FE-227,
and FE-241. These materials are claimed to have all the advantageous
properties of halon, but lower toxicity, and zero ozone depletion
potential. They require about 50% greater concentration for equivalent
fire quenching.
Specialised materials for Class D
Class D fires involve extremely high temperatures and highly reactive
fuels. For example, burning magnesium metal breaks water down to
hydrogen gas and causes explosions. It breaks halon down to toxic
phosgene and fluorophosgene and may cause a rapid phase transition
explosion. It continues to burn even when completely smothered by
nitrogen gas or carbon dioxide, in the latter case producing toxic
carbon monoxide. Consequently there is no one type of extinguisher
agent that is approved for all class D fires rather there are several
common types and a few rarer ones. Each must be compatibility approved
for the particular hazard being guarded. Additionally, there are
important differences in the way each one is operated, so the operators
must receive special training.
Some class D extinguishing agents include finely granulated sodium
chloride, copper and graphite applied by an extinguisher, shaker,
scoop or shovel. These extinguishing agents are suitable for sodium,
potassium, magnesium, titanium, aluminium, and most other metal
fires.
Finely powdered graphite, applied with a long handled scoop, is
preferred for fires in fine powders of reactive metals, where the
blast of pressure from an extinguisher may stir up the powder and
cause a dust explosion. Graphite both smothers the fire and conducts
away heat.
Finely powdered copper propelled by compressed argon is the currently
preferred method for lithium fires. It smothers the fire, dilutes
the fuel, and conducts away heat. It is capable of clinging to dripping
molten lithium on vertical surfaces. Graphite can also be used on
lithium fires but only on a level surface.
Other materials sometimes used include powdered sodium carbonate,
powdered dolomite and argon.
As a very poor last resort dry sand may be used to smother a metal
fire if nothing else is available. It should be applied with a long-handled
shovel to avoid the operator receiving flash burns. Sand is, however,
notorious for collecting moisture and even the smallest trace of
moisture may result in a steam explosion, spattering burning molten
metal around.
Return to Extinguishers
|
