Issue 1 Jan 03
INTERNATIONAL FIRE TRAINING CENTRE
FIREFIGHTER INITIAL
FIRE EXTINGUISHING MEDIA – WATER
Throughout this note he means he/she and his means his/hers.
Areas considered to be of prime importance are in bold type
INTRODUCTION
Water is the most efficient, cheapest and most readily available media for extinguishing fires of a
general nature. It is used by the Fire Service in one form or another in the majority of situations. It is
essential that the firefighter selects water as an extinguishing agent in the right circumstances and
applies it correctly.
AIM
The aim of this training note is to make students aware of why, when and how water is used by the
Fire Service at incidents.
OBJECTIVES
After participating in the theoretical and practical sessions dealing with this subject and with careful
study of this training note you will be able to;
•
•
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State the reasons why water is used extensively by the Fire Service
Explain the circumstances in which it should and should not be used
Describe the methods of application
With any extinguishing media, an understanding of its uses, limitations and associated hazards can
be gained by considering its advantages and disadvantages. These can help us to select the
appropriate media to suit a set of circumstances and, where there is choice, make an informed
judgement as to which is best.
ADVANTAGES
•
Easily Moved
Water is relatively easy to move in large quantities from one place to another. In the
circumstances of an operational incident, water can be transported quickly in vehicle
tanks to the area where it is urgently required. It can then be put to work more precisely
making use of pumps, fire-hose, branches and the skill and knowledge of the firefighter.
•
Readily Available
Water can be found in plentiful supply in the vicinity of most incidents. It falls to us to
have an operational plan to move it from its source to exactly where it is needed. These
supplies of water can be in the form of;
i) First Aid Firefighting Equipment
ii) Water On Vehicles
iii) Hydrant Systems
Issue 1 Jan 03
iv) EWS Tanks
v) Natural Supplies
NOTE: An explanation of each of these is described further on within this training note.
Used at the majority of fires
Water is the most frequently used extinguishing agent and is used at the majority of incidents
in one form or another. It is sometimes used directly to cool Class A materials and sometimes
indirectly e.g., as the base of a foam blanket.
Can protect the firefighter
If a hand controlled spray branch is used and the diffuser nozzle set for a wide spray pattern,
protection can be gained by putting this between the firefighter and the fire.
Excellent cooling properties
As water changes from its liquid state into a vapour (steam) it is capable of absorbing vast
amounts of heat. This means that if it is applied correctly it can reduce the temperature of fuel
to the point that the fuel is not giving off enough vapour for the combustion process to
continue. It can also be used to great benefit to cool and so protect things that are close to a
fire and in danger of becoming involved.
Low hazard
Clean water as a substance can be viewed as non-toxic and therefore minimally hazardous to
the firefighter. Caution must however, be exercised because water used in the wrong
circumstances can be extremely dangerous.
DISADVANTAGES
Conductor of electricity
Water is a very good conductor of electricity which means it must not be used where ‘live’
electrical equipment is involved. The use of jets near to overhead power cables can be
particularly dangerous especially at night when the cables may not be easily visible.
Heavier and non-miscible with aviation fuels
In the Airport Fire Service the main risk is aviation fuel. Water, being heavier and non-miscible
with aviation fuel, could worsen the situation at an aircraft accident. Water, if applied to a fuel
spillage, would sink causing fuel to float on the surface possibly spreading the fuel to a wider
area or carrying it into drainage systems.
Can cause extensive damage
If more water is applied than is actually required to contain and extinguish the fire, the surplus
will drain off and may cause more damage than the fire itself. It should always be the aim of
firefighters to use only the minimum amount of water to prevent un-necessary damage and
conserve supplies.
Issue 1 Jan 03
Can react violently
The use of water in the wrong circumstances or incorrect application techniques can lead to
dangerous and violent reactions. It is now widely known that to use water on most liquid fuels
may lead to sudden fire development. The use of water on fires involving combustible metals
can also lead to very violent reactions with molten metal being projected in all directions with
explosive force.
WATER SUPPLIES AT INCIDENTS
First aid firefighting equipment
Although this type of equipment is designed to be used by anybody with minimal training on
small Class A fires, they should not be overlooked because of their portability, immediate
availability and ability to deal with small fires with little mess.
Water on vehicles
Airport fire vehicles are required to carry set minimum quantities of water for producing foam.
Although these amounts may sound a lot, with the output capabilities of modern monitors,
even the largest tanks could be emptied within three minutes.
Hydrant systems
Hydrant systems vary from airport to airport. Some have hydrants in easily accessible
positions around runways and taxiways. Others may have fewer hydrants in more remote
positions. The output from hydrants can change at different times of day according to local
demand. In some cases the pressure in hydrant mains can be increased on request to the
supplying authority.
Ews (emergency water supply) tanks
At some airports the water available in vehicle tanks can be supplemented from EWS tanks.
These tanks can normally be found at the ends of, and around halfway along, the runway.
Natural supplies
These can be rivers, lakes or the sea. They can give an excellent inexhaustible supply of water
but can be subject to seasonal or tidal change.
Water supplies at airports is an important issue. The objective is always to provide a
continuous water supply as soon as possible to wherever an incident occurs on, or in, the
vicinity of the airport. Each airport will have its own unique set of circumstances but will also
have a well-tested plan for achieving its objective.
AREAS OF APPLICATION
Class A materials
As previously mentioned, water is an ideal extinguishing media for dealing with Class A materials. In
a fire, Class A materials first need to be turned into a vapour. This requires heat. Because water can
absorb vast amounts of heat it is capable, if applied correctly, of reducing the temperature of the fuel
to the extent that it is no longer producing enough vapour for the combustion process to continue.
As a base for foam
Water is used as the base for most firefighting foams. Around 95% of any foam solution is in fact
water. In many cases the foam concentrate that is added to water has no firefighting properties, it
simply changes the characteristics of water to allow it to float on the surface of fuel rather than
sinking. This, in turn, smothers the fire.
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Spray for cooling
We have already mentioned the excellent cooling ability of water. An example of where this is
particularly beneficial is when areas of an aircraft have been exposed to radiated heat from a fire.
The application of water can cool these areas to limit damage and prevent further involvement in the
fire.
Curtain for protection
As well as having the ability to cool already heated structures, water can prevent heating in the first
place. This can be done either by wetting areas down or by discharging the water in a wide spray
pattern and using the spray as a protective curtain.
Decontamination
In most cases, decontamination is carried out by washing personnel and equipment down with clean
water and then disposing of the contaminated water correctly.
METHODS OF APPLICATION
Spray
When water is applied as a spray it produces its most efficient cooling action. Water, in the form of a
spray, can also be used to drive smoke or gas. An example of this would be using spray to drive
smoke from an aircraft fuselage. This requires an action similar to a syringe where a water spray from
one end of the fuselage moves towards the other. For this to work there must be a smoke exit point
at the opposite end of the fuselage to the spray.
Jet
We do not often use jets for firefighting. The main reason for this is, as previously stated, water
produces its most efficient cooling action when applied as a spray. Each droplet of the spray absorbs
heat and removes it from the area of the fire. When applied as a jet, most of the water passes
through the affected area with little benefit to the firefighting operation.
Pulse
A method for extinguishing fires inside compartments is to apply water in a pulsed spray by quickly
opening and closing the branch. If water were to be applied into a hot compartment continuously for
two minutes, around 1000 litres or one tonne of water would have been used and up to 17,000 m3 of
steam created. The pulse method can be just as effective as continuous application, however there is
a danger of burst hoses due to water hammer caused by the rapid closing of the branch.
HAZARDS TO PERSONNEL
The main hazards presented by water, to personnel, are as follows:
Electrocution
Ice
Steam
Jet Power
Contaminated Water
Caused by water contacting ‘live’ electrical equipment.
Water running off a fire on a cold day can turn quickly to ice causing
slip hazards.
This is a particular hazard in enclosed spaces or where a lot of metal is
present
Due to the speed that water is ejected by a monitor or branch, there is a
danger that anyone struck by this could be seriously injured.
Water used at fires comes from a multitude of sources and is not
always clean. This can pose a health risk if accidentally swallowed or
good hygiene is not observed.
Issue 1 Jan 03
SUMMARY
Water is the most efficient, cheapest and most readily available media for extinguishing fires of a
general nature. Having an understanding of the advantages and disadvantages of its use will help the
firefighter to select it as an appropriate extinguishing agent in the right circumstances. They will also
be capable of making an informed judgement on how it should be applied and the hazards associated
with the use of water at incidents.