A fire extinguisher can stop a small fire from becoming a disaster. In the first minute, a fire may be no bigger than a waste paper bin. A few minutes later, it can fill a room with smoke and spread beyond control.

But an extinguisher is only useful in the hands of someone who knows which one to use, when it is safe to use it, and how to use it properly. The wrong extinguisher, or the right one used badly, can make a fire worse and put lives at risk.

This course gives you that knowledge.

This course is designed for fire wardens, fire marshals and anyone who may be expected to use a fire extinguisher at work. It is also useful for anyone who wants to understand fire extinguishers and use them safely.

It covers the knowledge you need. Your employer should also give you hands-on practice with real extinguishers, so that you know how they feel and sound when they are discharged.

Remember: nobody is ever required to put themselves in danger to fight a fire. Your safety always comes first.

By the end of this course you will be able to:

• Explain the fire triangle, and the classes of fire.
• Identify the different types of fire extinguisher, and the fires each one is used on.
• Decide whether it is safe to tackle a fire.
• Use fire extinguishers and fire blankets safely and effectively.
• Know what to do if a fire cannot be put out.

In this module you will learn about:

• Why fire extinguisher training matters.
• The fire triangle.
• The classes of fire.
• The types of fire extinguisher, and their colour codes.
• How many extinguishers a workplace needs, and where they go.

Many people have never used a fire extinguisher. In a real fire, with noise, smoke and panic, they may:

• Pick up the wrong extinguisher, for example water for an electrical fire.
• Stand too close, or aim at the flames instead of the base of the fire.
• Carry on too long, and become trapped as the fire spreads.
• Delay raising the alarm while they try to deal with the fire alone.

The Safety, Health and Welfare at Work Act 2005 requires employers to appoint and train people to carry out fire fighting and evacuation.

Fires wreak havoc in Ireland every year, leaving businesses in ruins whatever their size or location. Every year, thousands of fires break out in Irish workplaces and other non-residential buildings, causing deaths, burns and smoke injuries, many of them in industry, retail and food premises. Beyond the damage to buildings and the harm to people, a fire can interrupt operations, destroy valuable assets and erode the trust of clients, and many businesses find it very hard to recover.

Knowing how to use an extinguisher prepares you for an emergency and makes you a first line of defence for the people around you and for the business that employs you.

Every fire needs three things: heat, fuel and oxygen. Together they are called the fire triangle.

Fire extinguishers work by removing one side of the triangle:

• Water cools the burning material, removing the heat.
• Foam and wet chemical form a layer over the fuel, cutting off the oxygen and stopping vapour escaping.
• Carbon dioxide pushes away the oxygen around the fire.
• Powder interrupts the chemical reaction of the fire, and smothers it.

You hope never to use an extinguisher, but you need to understand what makes a fire. Ignition is any source of heat that can start one. Common examples are open flames, overheated surfaces, faulty or overheating equipment, blocked ventilation, static electricity, carelessly discarded smoking materials and equipment that produces friction. Fuel is anything that can burn and keep the fire going, such as paper, cardboard, plastics, timber, textiles, rubber, foam, flammable liquids and gases, and some chemicals.

Oxygen is the third element. The most obvious source is the surrounding air, but oxidising chemicals and stored oxygen cylinders can supply it too. Take away any one of the three and the fire will go out, which is exactly how every type of extinguisher works.

Fires are grouped into classes by the fuel that is burning:

• Class A: solid materials, such as paper, wood, textiles and many plastics.
• Class B: flammable liquids, such as petrol, oil, paints and solvents.
• Class C: flammable gases, such as propane, butane and natural gas.
• Class D: burning metals, such as magnesium, aluminium and lithium.
• Class F: cooking oils and fats.

Electrical fires are not a class of their own, because electricity is a source of ignition, not a fuel. But live electrical equipment needs an extinguisher that will not conduct electricity.

Choosing the right extinguisher starts with knowing the class of fire. Class A fires burn ordinary solid or organic materials, for example wood in furniture or construction, plastics, paper products, and fabrics such as curtains and upholstery. Class B fires are fuelled by flammable liquids. Common examples are cleaning solutions, alcohol, petrol and diesel, and paints and lacquers. Class C fires are fuelled by flammable gases, including propane, butane, methane and some aerosols.

Class C fires carry particularly high risk because gas can explode, so you should never try to put out a gas fire unless the supply has been shut off. Each class needs a suitable extinguisher, and using the wrong one can make the fire much worse.

Three further types of fire need special care. Class D fires involve combustible metals such as magnesium, lithium, sodium, titanium and aluminium, including the shavings known as swarf. The wrong method can make the blaze worse or scatter burning fragments. Electrical fires involve live equipment, such as overloaded sockets, short-circuited devices, overheating machinery and damaged cables. They are not a formal class, because electricity is a source of ignition and not a fuel, but it helps to think of them as an unofficial Class E when choosing an extinguisher.

Class F fires are caused by cooking oils and fats, including vegetable, sunflower and olive oil and animal fats such as lard and butter. They burn at such high temperatures that they are difficult to control without the correct extinguisher.

All fire extinguishers have a red body. A coloured band or label shows the type:

• Red: water.
• White: water mist.
• Cream: foam.
• Black: carbon dioxide, also called CO2.
• Blue: dry powder.
• Yellow: wet chemical.

The label also shows, in pictures and words, which classes of fire the extinguisher can be used on, and any it must not be used on. Always read it before use.

• Water extinguishers are for Class A fires only: paper, wood, textiles and other solids. They cool the burning material. Never use them on burning liquids, cooking oil or live electrical equipment.
• Some water extinguishers contain additives that make them more effective, but the same limits apply.
• Water mist extinguishers spray very fine droplets. Depending on the model, they can be used on Class A, B and F fires, and on electrical equipment up to a stated voltage. They leave little mess. Always check the label, because models differ.

There are two kinds of water extinguisher. A standard water extinguisher releases water at high pressure, which cools the flames. Some hydrospray models cover a wider area, and some contain chemical additives that make them more effective. They are meant for Class A fires involving wood, paper and fabrics, and must never be used on any other class. A water mist extinguisher is more versatile. It turns water into microscopic dry particles that cool the flames and deprive them of oxygen.

The mist forms a protective barrier between you and the fire, deflecting some of the heat, and it leaves no residue behind. It is suitable for Class A, F and electrical fires. Some models are also rated for Class B fires, so always check the label, because models differ.

• Foam extinguishers are for Class A and Class B fires. They form a blanket over burning liquids, smothering the fire and stopping it re-igniting. Do not use them on live electrical equipment unless the label says they have been tested for this.
• Carbon dioxide extinguishers are mainly for fires involving electrical equipment, and are also effective on small Class B fires. They leave no residue, so they do not damage equipment. But the gas disperses quickly, so the fire can re-ignite, and they are not effective on Class A fires such as burning paper.

A foam extinguisher is mainly water with a foaming agent added, which makes it effective against fires fuelled by flammable liquids. It works by smothering the flames and laying a seal over the liquid vapours, which prevents the fire from reigniting. It is suited to Class A ordinary combustibles and Class B flammable liquids, and it is particularly efficient on petrol and diesel fires, because the foam forms a barrier that locks the vapours in.

There are important limits. Do not use foam on electrical fires. The water content means electricity can pass along the discharged liquid and give you an electric shock. Foam is also not recommended for Class F fires involving cooking oils and fats, or for metal fires.

Carbon dioxide extinguishers put out a fire by replacing the oxygen around it with CO2, which starves the flames. Their great advantage is that they leave no residue, which makes them ideal where there is a lot of electrical equipment, such as offices, server rooms and workshops, and wherever cleanliness and avoiding contamination matter. They are suitable for Class B flammable liquid fires and for fires involving electrical equipment.

There are two warnings. CO2 is not recommended for Class F fires, because the powerful jet can splash burning oil or fat and spread the fire. And CO2 does not cool the burning material very much, so there is a risk of reignition if the source of ignition has not been removed.

• ABC dry powder extinguishers can be used on Class A, B and C fires, and on electrical equipment. But the powder cloud makes it hard to see and breathe, so they should not normally be used indoors in small rooms. They are common in vehicles, forecourts and outdoor areas.
• Specialist powder extinguishers, such as M28 and L2, are made for Class D metal fires. L2 powder is used on lithium. They are only provided where metals that burn are used.
• Wet chemical extinguishers are for Class F fires in deep fat fryers and cooking oils. They cool the oil and form a soapy layer that seals the surface.

ABC extinguishers contain a specialised powder that interrupts the chemical reaction of the fire and smothers it, and they are rated for Class A ordinary combustibles, Class B flammable liquids and Class C flammable gases. Their main drawback is the residue. The powder is difficult to clean up and can damage surfaces and devices. Although it can deal with an electrical fire, it is not advisable to use it on electrical apparatus, because the leftover powder may ruin the equipment.

It must also not be used on Class F fires involving cooking oils and fats. The powder cloud makes it hard to see and breathe, so ABC extinguishers are not suitable for small enclosed rooms. In a small room, choose an extinguisher that suits both the class of fire and the surroundings.

M28 and L2 extinguishers are designed for Class D fires fuelled by combustible metals, particularly metal swarf and powders. Burning swarf is dangerous because a puff of wind can scatter it, so these extinguishers are built to release their powder gently. A distinctive hose tells them apart from ABC extinguishers, so always check the text, the symbols and the shape of the nozzle before you use one. The L2 type can deal with every kind of metal fire, including those started by lithium.

The M28 type also deals with all metal fires, except those involving lithium. Never use either extinguisher on any fire other than Class D, and never use any other type of extinguisher on burning metal swarf.

Wet chemical extinguishers are made for Class F fires, particularly those caused by heated cooking oils and fats. The chemicals inside reduce the flames, bring down the temperature of the hot oil, and form a detergent-like layer over the surface that prevents the fire from starting again. Like the M28 and L2 types, a wet chemical extinguisher has a distinctive hose that releases its contents as a controlled mist, so the hot fat or oil is not scattered.

Wet chemical extinguishers could be used on some other classes of fire, but it is advisable to choose a more suitable extinguisher for those. For anything other than a cooking fire, look for the extinguisher whose label matches the fuel.

The number and type of extinguishers is decided by the fire risk assessment. As a general rule:

• Most buildings need at least two Class A extinguishers on every floor, unless the floor is very small.
• Extra extinguishers are provided for special risks, such as carbon dioxide near electrical equipment and wet chemical in kitchens.
• Extinguishers are placed on escape routes, near exits and beside the hazard, so that you never have to go past a fire to reach one.
• They are mounted on brackets or stands, with a sign above, so they are easy to see and reach.
• Selection, siting and maintenance follow the Irish Standard IS 291.

In most workplaces there should be at least two extinguishers on every floor of up to 400 square metres, with a combined rating of at least 26A. The types required depend on the size of the premises and the activities carried out there, and a risk assessment is used to decide this. A restaurant with deep fat fryers, for instance, faces the risk of Class F fires and needs wet chemical extinguishers.

Hands-on training is normally given only for the types of extinguisher that are actually in your workplace. Even so, understanding all the types is valuable, because it helps you decide which to use and, just as importantly, which to avoid in any fire situation you may meet at work.