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Fire safety: understanding fire classes and extinguishers


With the fire season already affecting some regions, and warm, dry weather conditions likely to continue, authorities are urging all Australians to be fire ready. For business owners and facility managers, fire preparation should include conducting a thorough risk assessment to ensure the right suppression equipment is in place, and in proper working order.

There are six main types of fire extinguisher available in Australia – water, foam, dry powder, carbon dioxide (CO2) or wet chemical and vaporising liquid – with each identifiable by a coloured band denoting the contents.

Knowing which equipment is best suited for your workplace is important in order to meet regulations, and protect the lives of workers.

However, being equipped to prevent flames from engulfing your business premises first requires an understanding of the different fire types, and how each should be treated, remembering that not all fires, or extinguishers, are the same.

What are fire classes?

Fires are divided into six classes, according to what fuelled the fire. Categorising fuels in this way can help to identify the type of extinguisher required.

Class A: Wood, Paper & Plastic

Class A is the most common type of fire encountered by firefighters and may involve clothing, rubbish bins or a pallet of cardboard. Most suppression types are effective for Class A fires, except for extinguishers that use carbon dioxide.

Class B: Flammable & Combustible Liquids

Fires that involve flammable, combustible liquids such as petrol, kerosene, oil, tar, paint, wax, cleaning spirits or alcohol are known as Class B. Dry powder extinguishers are the most suitable for this fire class, and it is also possible to use foam or carbon dioxide. Importantly, it is dangerous to use water to suppress this class of fire – especially a grease fire.

Class C: Flammable Gases

This class of fire involves combustible gases such as LPG (liquefied petroleum gas), butane, propane; or LNG (liquefied natural gas, acetylene). Extinguishing a gas fire should not be attempted unless the gas supply has been first shut down, and only a dry powder extinguisher should be used.

Class F: Cooking Oils & Fats

Most Class F fires start in kitchens and involve vegetable or olive oil, lard, butter or dripping used in cooking. There are different ways to treat this type of fire but it’s important to be aware that you should never use water because it can spread the flames. A wet chemical extinguisher should be used.


Different fire extinguisher types

The right fire equipment can be the first line of defence against a fire hazard. With proper use a portable fire extinguisher can reduce or eliminate the degree of injury, damage and cost to business in the event of a small fire, however, it is essential to understand which extinguisher type should be used.

The coloured band around the extinguisher identifies the type of suppression used:

  • Red (water) only suitable for Class A and not safe on other classes of fire
  • Blue (foam) only suitable for Class A and B fires
  • White (dry powder) suitable for Class B, electrical fires (E) and also suitable on Class A fires (ABE)
  • Black (carbon dioxide) suitable for (E) and Class B fires. This extinguisher has a noisy and cold discharge, and users should beware of discharge pressure.
  • Yellow (vaporising liquids) suitable for (E), Class A fires
  • Oatmeal (wet chemical) suitable for Class A and F fires.

Safety tips for fire extinguisher use

Storage: ensure fire extinguishers are stored in an easy to reach location in the event of a fire emergency, yet stored away from areas likely to catch fire.

Service: regular maintenance of your extinguisher is crucial. This includes monitoring the pressure gauge, shaking the extinguisher occasionally to prevent the powder from settling and having a six monthly or an annual check by a fire protection professional. When it comes to replacing an old extinguisher, contact Wormald for information on disposal options.

Using your extinguisher: Wormald recommends Fire Extinguisher Training to ensure all staff, not just fire wardens, feel fully prepared to act in a fire emergency. An important safety rule is to ONLY use a fire extinguisher if:

  • you know that the extinguisher is suitable for use on the flammable materials involved in the fire;
  • you have checked whether electricity is possibly involved and, if so, that the available extinguishing agent is non-conducting;
  • you can extinguish the fire quickly;
  • you are not putting your safety at risk by staying in the vicinity of the fire; and
  • all other persons have been evacuated from the area. Read more about fire evacuation plans.

Remember to always choose a fire extinguisher that has been approved as meeting Australian Standards and ensure you read the operating instructions well before a fire hazard occurs.

Wormald offers a range of portable fire equipment and fire extinguishers to suit all types of fire class. For further information contact our team on 133 166.