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Understanding Fire Extinguishers and Their Uses

May 09, 2019

Whilst you probably don’t see them as you walk around, the truth is, Fire extinguishers are all around us. You just take little notice of them because in all likelihood, you have never had a need to use one, and never think you will.
And now we have you thinking about them, let us ask this: are you aware that there are actually different types of extinguishers and that there's no one-size-fits-all solution to putting out a specific fire? It may not seem a big thing, but lack of knowledge could be the difference between a small fire that could have been prevented, or a large scale catastrophic one that traps people and causes thousands or millions of dollars in damages.
For this reason alone, today’s blog focusses on why it is important understand which fire extinguisher is ideal for your home, office, warehouse, or industrial space, and which one works best to counteract a specific type of fire.

Learning about different types of fires

Whilst there are five main fire extinguisher types: water, foam, dry powder, CO2, and wet chemical to put out fires, there is no one-extinguisher type that works on all classes of blazes. In fact, some extinguishers will do more harm than good (feeding the fire or spreading it) if you use it incorrectly, so let’s take a look at the six classes of fire that determine the risk associated.

  • Class A fires – These are fires caused by basic combustible materials like wood, paper, and fabric.
  • Class B fires – These are the type triggered by flammable liquids such as petrol, turpentine or paint.
  • Class C fires – These are conflagrations initiated by flammable gases like hydrogen, butane, or methane.
  • Class D fires – These are fires caused by combustible metals and chemicals such as magnesium, aluminium, or potassium.
  • Electrical fires – As its name suggests, these are fires started by any electrical equipment found in the premises. Remember, once the electrical item is removed, the fire changes class.
  • Class F fires – Blazes under this class, which are typically considered pan-chip fires, are caused by cooking oils and the like.

Each fire type is characterised by different flame type, different temperatures, means of spreading and thus, control. To successfully respond to and contain a fire, you should learn how to identify the various fire extinguisher types designed for specific kinds of fires. Because there is a lot to remember for something which happens rarely, manufacturers have attached labelling and a colour coding to each bottle.

  • Water extinguishers. They are the most common fire extinguisher type for Class A fire risk in most premises and properties. They are BRIGHT RED in colour and used for organic materials such as paper, cardboard, fabrics and textiles, wood and coal.
    Do not use them for fires involving electrical equipment, kitchen fires, flammable gas and liquids. Doing so can spread the flames or conduct electricity which will kill someone.
  • Foam extinguishers. They are the most common type of fire extinguisher for Class B fires, but also work on Class A fires as they are water-based. They are CREAM in colour and used for organic materials such as; paper and cardboard, fabrics and textiles, wood and coal including flammable liquids like paint and petrol.
    Do not use them for kitchen fires, fires involving electrical equipment and flammable metals.
  • Dry Powder Extinguishers. Standard dry chemical fire extinguishers are also called ‘ABC’ extinguishers as they tackle class A, B and C fires. However, they are not recommended for use in enclosed spaces because the powder can be easily inhaled; also the residue is very difficult to clean up after. These extinguishers can also be used on some electrical fires while specialist dry powder extinguishers are also used for flammable metals. They are BLUE in colour and used for organic materials—paper and cardboard, fabrics and textiles, wood and coal—flammable liquids (paint and petrol), flammable gases (liquid petroleum gas or LPG), and acetylene, as well as fires involving electrical equipment up to 1000v.

Specialist dry powder extinguishers are ONLY used on flammable metals, such as titanium and magnesium. Do not use them for fires involving cooking oil, fires involving electrical equipment over 1000v or in enclosed spaces, such as offices or residential properties.

  • Carbon Dioxide (CO2) Extinguishers. CO2 extinguishers are predominantly the fire extinguisher for electrical fire risks and are the main extinguisher type provided in offices or computer server rooms. BLACK in colour, they also put out Class B fires (flammable liquids, such as paint, paraffin or petroleum). Carbon dioxide extinguishers do not leave any residue, unlike a foam extinguisher. Do not use them for kitchen fires (especially chip-pan fires), combustible materials (paper, wood, textiles) or flammable metals.
  • Wet Chemical Extinguishers. Wet chemical extinguishers are suitable for use on Class F fires involving cooking oils and fats, such as lard, olive oil, sunflower oil, maize oil and butter.  They are YELLOW in colour and extremely effective when used correctly.  The wet chemical rapidly knocks the flames out, cools the burning oil and chemically reacts to form a soap-like solution, sealing the surface and preventing re-ignition.  

Although primarily designed for use on Class F fires, cooking oils and deep fat fryers, they can also be used on Class A fires (wood, paper and fabrics) and Class B fires (flammable liquids). Do not use them for flammable liquid or gas fires, electrical fires and flammable metals.

How to use a fire extinguisher

Fire extinguishers should not be used by people who have not been trained (unless there is no alternative or other person around), not only on how to use an extinguisher properly, but also how to accurately assess a situation and determine when evacuation is the safest course of action. Before tackling a fire, make sure you or someone else has sounded the fire alarm and that you have a safe evacuation route. Using the correct type of extinguisher for the fire, use the four-step PASS technique, which is approved and used by councils and agencies across the world.

  • Pull: Pull the pin located at the top of the extinguisher. Doing so will break the tamper seal.
  • Aim: Aim low, pointing the nozzle or hose at the base of the fire. Do not touch the horn on a CO2 extinguisher as it gets very cold and can damage the skin.
  • Squeeze: Squeeze the handle to release the extinguishing agent.
  • Sweep: Sweep from side to side at the base of the fire (the fuel source) until the fire is out.

If there is the slightest doubt or uncertainty about tackling the fire, evacuate the building immediately.
Also, ensure to refer to the Australian Standard 2444 (AS 2444) Portable Fire Extinguishers and Fire Blankets for more information about government-approved fire safety equipment and processes.
Above all, stay safe!

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