What type of Fire Extinguisher do I need?

September 4th, 2017

In this modern world we still don’t have a fire extinguisher that can put out every type of fire. For many of you reading this the idea that there are different types of fire is a new concept – isn’t fire just fire? No its not, it’s a little more complicated than that. This article helps to explain the type of fire extinguishers that you will need for your workplace.

The Fire Triangle

Before we get into the details about the fire types we need to understand the basic chemistry of fire. Fire will only occur if there are 3 elements co existing, they are a fuel source, oxygen and an ignition source (which can be a spark or sufficient heat to cause ignition). This is commonly called the fire triangle.

 

 

Classification of Fire

A fire is classified by what the fuel source is. To make this easy letters of the alphabet are used, A through to F. The different types of fires are also represented on the front of the fire extinguishers with a pictogram. Class D fire is a metal fire which is not found in most workplaces.
class cut 2

Types of Fire Extinguishers

There are 5 main types of fire extinguishers:
Water
Foam
Carbon Dioxide gas (CO2)
Dry Powder. Dry Powder are further divided into ABE Dry Powder, BE Dry Powder and specialist Powders for metal fires.
Some of these fire extinguishers are used on more than one classification of fire. To assist you determine which fire extinguisher you should have refer to the figure below that outlines which type of fire extinguisher can extinguish which class of fire.

Precautions
While using a fire extinguisher on a fire that it is not designed for may have only minimal impact there are a few exceptions
Air Water fire extinguishers are not suitable for use on electrical (class E) fires. Water conducts electricity, you are holding a steel cylinder full of water with a water stream onto a source of electricity – you may be electrocuted.
Don’t use Air Water fire extinguishers on a petrol (class B) or fat (class F) fire. When the water lands on the fire it is immediately turned into steam. This steam carries small fuel particles into the air which subsequently ignite into a large fire ball. Refer to the video of water being poured onto a cooking fat fire.

Don’t use a CO2 fire extinguisher in a confined space. Oxygen will be displaced by the CO2 gas, if this occurs in a small space, such as a toilet then the oxygen levels may become below tenable levels.
It is also worth noting that some fire extinguishers, such as Air Water and CO2 are considered clean while others are dirty. A clean fire extinguisher means that the contents of the fire extinguisher will dissipate over time, water will evaporate etc. While the dirty fire extinguisher will leave a mess to be cleaned up. This mess is substantially less than the mess caused by a fire!
So Which Fire Extinguisher Do I Need?
To determine what type of fire extinguishers you need your first task is to identify what fuel sources you have in your building. Some of these will be isolated to one location, such as Fats (class F) in a kitchen, while others may be distributed about the whole buildings, such an Electrical hazards (class E) in an office.
From this information you can determine what type of fire extinguishers to use, to help here are a few examples.
In an office there are electrical (class E) and wood / paper (class A) fuel sources. Therefore an ABE Dry Powder fire extinguisher could be used or a pair of CO2 and Air Water fire extinguishers if a more clean extinguishing agent is preferred.
In a restaurant there is cooking fat (class F) fuel sources in the kitchen and electrical (class E), wood and paper (class A) throughout the whole building. Therefore a Wet Chemical fire extinguisher would be used in the kitchen and an ABE Dry Power or CO2 and Air Water pairs of fire extinguishers for the whole of the building.

How Many fire extinguishers Do I Need?
Now that you have determined what type of fire extinguishers you’re going to use you need to lay them out around the building.
Depending upon your reason for installing the extinguishers there are two standards to use, they are:
National Construction Code (Building Code Of Australia). This Code must be complied with when a building is constructed. Clause E1.6 Portable Fire Extinguishers and Table E1.6 Requirements For Extinguishers outlines the number and location of fire extinguishers in a building. The National Construction Code (Building Code of Australia) is available on line for free
Work Health and Safety Legislation (in South Australia) does not specify the standard to use, however it is considered that compliance with Australian Standard AS 2444-2001 ‘Portable Fire Extinguishers And Fire Blankets – Selection And Location’ will ensure compliance with Work Health and Safety Legislation and the National Construction Code. This standard can be down loaded (for a small cost from SAI Global)
The interpretation of both of these standards can be difficult. Our recommendation is to engage a fire protection contractor, Such as Fire and Emergency Services SA to review your site and provide you with recommendations of what fire extinguisher to install at what location. Many of these contractors will undertake this service for free as part of providing a quote to supply and install the fire equipment.
One thing to remember is it is better to have too many fire extinguishers than not enough. The cost of the fire extinguishers is relatively low compared to the cost of rebuilding a property, business or a life.
Where to go for more information
The staff at Fire and Emergency Services SA are always available to help you, just give us a call!