Yesterday, we wrote part 1 in our blog post explaining the different kinds of fire and how to extinguish them. Today, we’d like to follow it up with the last two kinds of fire and a little reminder of the three components of a fire triangle, which we covered in more detail in our dedicated Fire Triangle blog post. In part 1, we covered the following kinds of fires, all characterised by the kind of fuel they burn:
- Ordinary combustion fires – Class A
- Flammable liquids – Class B
- Flammable gases – Class C
- Metal fires – Class D
Cooking Oil Fires (Class F)
Cooking oil fires are very common in homes and in commercial kitchens. The cooking oil fuel in a class F fire is extremely difficult to extinguish because it reaches very high temperatures. One of the worst things you can do is use water or a water-based fire extinguisher to try and fight the flames. The water is more likely to scatter the oil, causing the fire to spread even faster. Adding water will also cause the burning oil to splatter in all directions, potentially injuring anyone close by.
Specialist wet chemical extinguishers have been developed to help fight cooking oil fires. The wet chemical extinguishers have a special formula that cools down the cooking oil and also emulsifies so that the surface of the cooking oil is sealed, stopping oxygen from getting at it, thus preventing reignition.
All businesses that use cooking oil on a regular basis should ensure that they have wet chemical extinguishers on their premises, and that their staff members know how to use them.
Although electrical fires don’t count as a specific class of fire, they are still worth discussing here, as extinguishing them can be difficult and very dangerous if you don’t know what you’re doing. The reason why electrical fires don’t count as a specific class of fire is because electric does not burn, so it is not actually the fuel that feeds the fire. Instead, electricity is the source of the ignition when it heats up or produces sparks.
Before you even think about extinguishing an electrical fire, it is important to turn off the source of electricity to the fire. Because water- and foam-based fire extinguishers conduct electricity, it is important that you do not use them to fight an electrical fire – even once the electricity source has been cut off. Instead, try using dry powder and carbon dioxide fire extinguishers as they will starve the fire of oxygen without running the risk of conducting electricity.
The Fire Triangle in Relation to Different Kinds of Fire
All of the different kinds of fire work in the same way, with three different components: fuel, heat, and oxygen. The only thing that changes the class of fire you’re dealing with is the fuel that’s burning. Understanding the basic fire theory could help you keep your workplace safe from fire.
Have a look around your workplace and assess what kind of materials are in the greatest abundance. Understanding this could help you spot potential fuel sources before a fire is ignited. This way, you can either prepare for that specific class of fire or separate and make safe the potential fuel. If you work in an office, for example, it is likely that there will be a lot of paper and wooden desks packed closely together, as well as many computers and electrical equipment. This means that the most likely fires to occur are Class A (ordinary combustion fires) and electrical fires. Make sure you have the right fire extinguishers for employees to fire electrical as well as Class A fires and that your staff know how to use them. It’s also a good idea to encourage staff to remove all paper from their desks and turn off all electrical appliances at the plug socket at the end of each working day. Doing this will remove the potential ignition source (the electricity) and a lot of the fast-burning fuel (the paper).
As with all workplaces, it’s important to carry out a risk assessment to work out if there are any potential fire hazards. If you identify potential ignition sources (usually sources of heat) and areas with a lot of highly combustible fuel, then you can take steps to make your workplace safer and to buy the right fire extinguishers for the job. With all kinds of fire, it’s a good idea to consider installing specialist fire-safety systems, such as our fire curtains or fire shutters. These barriers help slow down the spread of fire, saving lives and preventing damage to property by isolating the fire to a smaller area.