Fire is fire, right? It’s hot, it burns, it has a pleasing yellow glow and it can be immensely destructive if let loose. There’s only one type of fire. Yes? Or no? As a matter of fact, no. Fire is a lot more complicated than that. There are different classes of fire, and each one requires a specific firefighting method.
It’s crucial to know about the different classes of fire and the types of fire extinguishers. If you ever need to use a fire extinguisher, grabbing the right one can mean the difference between putting out a small fire or turning it into a raging blaze. It can also mean the difference between life and death.
This blog will provide you with the information you need to know what types of fires there are and what fire extinguishers to use in an emergency.
What Are the Different Classes of Fire?
What class of fire you are dealing with will impact how fast it can spread, how hot it will burn and what the best way to suppress or extinguish it is. Understanding the type of fire you’re dealing with is important to fighting it. Depending on the fire’s class, some extinguishers will put it out while others will make it worse.
There are six classes of fire. The different classes of fire are categorised according to their fuel source:
- Class A – Combustible materials
- Class B – Flammable liquids
- Class C – Flammable gases
- Class D – Burning metals
- Class F – Cooking oils and fats
- Electrical fires
Let’s consider the difference between each of these.
Class A – Combustible Materials
Class A fires are caused when a naked flame or an object at a very high temperature comes into contact with any type of organic solid material, also known as combustible materials.
Combustible materials are anything that has a flash point greater than 37.8°C and below 93.3°C. These fires burn hot and fast.
Combustible materials are commonplace and found almost everywhere. They can include:
- Wood
- Plastic
- Paper
- Coal
- Cloth
- Straw
- Cardboard
A water extinguisher should be used to put out a Class A fire.
Class B – Flammable Liquids
A Class B fire is caused by the ignition of a flammable liquid. Flammable liquids are incredibly volatile and hazardous and need to be stored and handled correctly. Unlike combustible materials, the ignition source doesn’t need to directly touch flammable liquids. The vapours from flammable liquids can ignite from just being near a flame or a spark.
Flammable liquids include:
- Petrol
- Diesel
- Thinners
- Oil
- Wax
Foam or powder fire extinguishers should be used to put out Class B fires.
Class C – Flammable Gases
Class C fires involve the ignition of flammable gases. These gases are housed in sealed containers and should only be handled by trained personnel. Class C fires can spread quickly and often result in explosions.
The most common types of flammable gases involved in Class C fires are:
- Butane
- Propane
- Methane
- Natural gas
A dry powder extinguisher should be used to put out a Class C fire.
Class D – Burning Metals
Metal takes a lot of heat to burn, but it can happen. Not all metals are flammable and the ones that are can usually be found in specialised environments like laboratories, metal fabrication workshops or industrial warehouses. These fires spread quickly and can be highly destructive.
Flammable metals usually include:
- Sodium
- Potassium
- Uranium
- Lithium
- Plutonium
- Aluminium
- Titanium
Water extinguishers must not be used for Class D fires. Dry powder extinguishers are used to put out Class D fires.
Class F – Cooking Oils and Fats
Class F fires are common and can rage out of control quickly if they’re not dealt with properly. These fires involve the ignition of cooking oils, greases and fats.
Technically, a Class F fire is actually a sub-class of Class C, but they are allocated their own classification due to their high flash points. A Class F fire requires a temperature of close to 340°C to ignite. When they do start, Class F fires are fierce.
Class F fires normally start in kitchens or restaurants when cooking oil or grease falls onto an open flame, when pans are left unattended or when the oil isn’t changed in deep fryers.
Water extinguishers must not be used for Class D fires. Wet chemical extinguishers or fire blankets are used to put out Class D fires.
Electrical Fires
Electrical fires are something of an anomaly. They aren’t given their own classification because electricity itself doesn’t burn. The material around an electrical current can and will burn, however. So, there’s no Class E, technically.
Electrical fires can be caused by overloaded sockets, faulty appliances or damaged equipment, frayed cables or wiring or short circuits.
You should never use water or foam extinguishers to put out an electrical fire. Only ever use a CO2 gas or a dry powder fire extinguisher on an electrical fire.
Types of Fire Extinguishers
There are five main types of fire extinguishers with three subcategories. Each type of fire extinguisher has its own code and its colour designation:
- Water – Water Mist and Water Spray (Red Labels)
- Foam (Cream Labels)
- Dry Powder – Dry Powder Standard and Dry Powder Specialist (Blue Labels)
- Carbon Dioxide (CO2) (Black Labels)
- Wet Chemical (Yellow Labels)
How to Use a Fire Extinguisher
If you have to use a fire extinguisher, then you need to take extreme care and make sure you have an exit route. Stand well back from the flames and place your back to an exit route. Follow the PASS procedure:
- Pull – Pull out the safety pin to prep the fire extinguisher
- Aim – Aim at the base of the flames
- Squeeze – Squeeze the trigger firmly, evenly and slowly
- Sweep – Sweep the spray from side to side across the base of the flames
You should never attempt to use a fire extinguisher unless you have received the proper training.
It’s highly recommended to take a fire safety course so that you know exactly what to do if an emergency arises.
Why Fire Safety Training is Important
Fires can happen at any time, anywhere and to anyone. They can be incredibly destructive.
If you own or run a business, then you have a legal obligation to ensure that your people receive adequate fire training and that you have the proper firefighting equipment and signage. You may even need to have fire wardens on site.
Our Fire Safety Courses will ensure you comply with fire-related health and safety legislation and protect your business and your people.
You can take these courses online at your convenience. Topics include fire awareness, fire risk assessments, fire door training and fire extinguisher use, fire safety inspection procedures and fire warden training.
