Fire is a constant danger when you're using flammable materials in any workshop. Your safety depends on whether you can
Identify the cause of the fire.
Identify the correct extinguisher to use on different fires.
Correctly operate the fire extinguisher.
Elements of fire
Fuel, heat and oxygen must be present before there can be a fire:
Fuel is anything combustible: any solid, liquid or gas that can burn, for example, wood, paper, oil, solvents and so on.
Heat can come from flames, sparks, friction, electrical sources, hot pipes and equipment.
Oxygen comes mainly from the air but also from some chemicals.
To put out a fire, remove one of the three elements by:
Removing fuel to starve the fire.
Removing oxygen to smother the fire.
Cooling the heat by using water.
Types of fire
The fuel that is burning dictates the kind
of extinguisher you use to fight the fire. To help you understand this
concept, you need to know how fires are classified and which fire
extinguishers are suitable for each class. We will look at the following
classes of fire A, B, E, and D.
Class A Fires
Class A fires start when materials such as paper, rubbish, wood, cloth or other carbon-based materials ignite.
Class B Fires
Class B fires involve flammable liquids such
as paints, oil and petrol. With these materials, its the vapours or
fumes that burn rather than the liquid. Because the vapours are lighter
than the air, they can drift away from the seat of the fire, and then
ignite, causing what's called a flash off. This instantaneously
increases the size of the fire and is very dangerous.
Class D Fires
Class D fires are fires involving
combustible metals such as sodium, magnesium, lithium and potassium.
Specialised dry powders are available to control these fires.
Class E Fires
Class E fires are electrical fires. They
usually start because of short circuit or arching in loose connections,
or because wiring becomes overheated. You must be very careful here
because there is the added risk of electrical shock as well as the
threat from the fire. Switch off the power if you can safely.
Types Of Fire Extinguisher
Fire Extinguisher Types NZ
There are five types of fire extinguisher found throughout the working environment, they are
Carbon Dioxide
Dry Powder
Foam
Water
Wet Chemical
The type of fire extinguisher you can use for each class of fire is as follows Class A Fires:
Water, dry powder, foam, co2 and wet chemical extinguishers are
suitable for this kind of fire. Your best plan of attack is to locate
the nearest fire hose. This will give you a constant stream of cold
water. The temperature at the base of the fire will cool to a point
below that needed for combustion to take place. Class B Fires:
these fires can be put out using foam, dry powder or co2 extinguishers.
These starve the fire of the oxygen it requires for burning. Water is
useless in these situations because it will only spread the fuel around
and increase the base of the fire. Class D Fires: these
fires require specialised powders and are usually designed for a
specific metal such as lithium, sodium, magnesium, etc. Sand can also be
used to smother the fire. Using water would produce hydrogen (H2) and
cause an explosion. Class E Fires: use dry powder or co2
extinguishers to fight electrical fires. Neither of these conducts
electricity, and both starve the fire of the oxygen it requires for
burning.
You must never use water on an electrical fire. Water and
electricity do not mix. Water is a good conductor and will suck the
electricity to the source of the water.
Fire extinguishers are
colour coded to help you identify the contents and which kind of fire
they should be used on. They have easy to follow operating instructions.
Make sure that you read these instructions before you have to use an
extinguisher. This will save you time in a real emergency situation and
help you feel more confident.
Fire Hose Reels
Fire
hose reels should be located to provide a reasonably accessible and
controlled supply of water to combat potential fire risks. The length of
a fully extended fire hose is normally between 18 to 36 metres. Hose
diameters are usually 13 or 19 millimetres ( internal measurement).
Fire
hose reels usually deliver a minimum of 14 litres of water per minute.
However, some hose reels have flows of up to 75 litres per minute. A
control nozzle attached to the end of the hose enables the operator to
control the direction and flow of the water.
Dry Powder Fire Extinguishers Dry Powder Fire Extinguishers are the most common fire extinguishers in New Zealand. Often referred to as Dry Powder, Dry Chemical or ABE Fire Extinguishers, they contain a dry chemical powder as the extinguishing agent. How to Identify A Dry Powder Fire Extinguisher Dry Powder Fire Extinguishers are a red cylinder with a white band running all around the top. Older, outdated models were an entire white cylinder. You can often see the words Dry Chemical printed on the front. Where To Use A Dry Powder Fire Extinguisher Due to their versatility, dry chemical fire extinguishers can be used in many different settings. They are suited for around the home, in the office, large factories and many other types of businesses. There are two kinds of dry chemical fire extinguishers on the market. ABE Fire Extinguishers As the name suggests, ABE fire extinguishers can be used to fight fires of class A, B, and E. This covers a wide range of hazards, including...
Classes Of Fire The fuel burning dictates the type of extinguisher you use to fight the fire. To help you understand this concept you need to know how fires are classified and which fire extinguishers are suitable for each class. Class A Fires Class A fires start when materials such as paper, rubbish, wood, or other carbon-based materials ignite. Dry powder, foam and water extinguishers are suitable for this class of fire. Your best plan of attack would is to locate the nearest fire hose. This will give you a constant stream of water. The temperature at the base of the fire will cool to a point below that needed for combustion to take place. Class B Fires Class B fires involve flammable liquids such as paints, oil, and petrol. With these materials, its the vapours of fumes that burn rather than the liquid. Because the vapours a lighter than air, they can drift away from the seat of the fire, and then ignite, causing what’s called a flash-off. This class of fire...
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