Class A Fires, they’re like the common cold of the fire world. Even as other modern fire risks take hold, like those posed by Lithium-ion Batteries, Class A just doesn’t go away. I’ll go into more detail soon, but for now I’ll tell you it includes wood, paper and rubber. That probably gives you an idea of what we’re dealing with.
But, naturally, being the most common type of fire, there are also the most ways to fight them. Water comes to mind, which is fair enough, as it is the most traditional method of extinguishing fires. We’ve used water for centuries, since long before fire extinguishers were invented, but it is only suitable for a limited range of fire types. Since then, we’ve come a long way.
What Exactly Are Class A Fires?
The general term for the fuel of a Class A Fire is Combustible Solids. That last word is pivotal; the solid state of matter is the primary attribute of Class As. This means there will always be a solid fuel source involved, the direct cooling of which is key to controlling them.
It can be said that a rule of Class A fires is that they produce ash. But the main cause is usually the material reaching a certain temperature, or coming into contact with a spark. These things can both cause ignition, and the materials they can ignite are what we call ‘ordinary combustibles’.
I’ve already implied the abundance of Class A fuel sources in our lives, but now to give you a sense of scale. Pretty much any solid that burns easily is an ordinary combustible, so homes and businesses are rife with them. As well as the examples above, general rubbish, plastics and straw also come under this category. That should give you a better sense of how common these materials are and, thus, Class A fires themselves.
Class A Fire Prevention Tips
Before we move on to extinguishers specifically, I want to run through some tips for avoiding Class A fires. You should be able to follow these at all times in the home:
- Install smoke detectors in key areas such as the kitchen, bedrooms and hallways, and test them on a monthly basis (*remember that these only give warning to the early stages of a fire, they don’t actually stop one from happening)
- Keep ordinary combustibles away from candles, stoves, and other high-heat appliances
- Do not leave cooking or candles unattended
- Dispose of cigarettes in a non-flammable container and keep matches and lighters out of reach from children
- Check wiring and cords for damage or fraying
- Avoid overloading sockets and extension leads, and turn off appliances when not in use
- And, of course, keep a Class A fire extinguisher easily accessible
And next, I’ve got a few pointers that are specific to the workplace:
- Follow standard procedure with smoke alarms*
- Keep extinguishers visible, accessible, and regularly inspected
- Conduct regular drills and safety training
- Keep appliances on non-flammable surfaces and turn them off when not in use
- Empty bins regularly and store paper, cardboard and fabrics away from high-heat equipment
- Keep storage areas clean and free from clutter
- Make sure electrical panels are unobstructed and replace damaged cords and equipment as soon as possible
Obviously, there’s some crossover between the two lists, and you should try and exercise as many points from each of them as possible, no matter where you are. So while it might seem like a lot, if you care about fire safety, you’d do well to treat most of this as gospel.
How Different Extinguisher Types Put Out Class A Fires (and the One that Can’t)
Powder, foam, and water, of course. These are the types of fire extinguishers you should be thinking about with Class A fires. There’s really only one common type of extinguisher you should avoid here: Carbon Dioxide. Not that CO2 extinguishers don’t have a throne of their own. They are the only type rated for use on electrical fires after all, which is part of the reason why they are also the perfect companion to your designated Class A extinguisher. CO2 puts out fires by displacing the oxygen that feeds the fire, but Class A fires burn within the structure of the material. This means that the fire is likely to survive until oxygen finds its way back to it.
In terms of what works, though, let’s start with water, the old reliable. Fires exist in a triangle of components: heat, fuel, and oxygen. Water extinguishers take the direct approach of removing heat from this equation. To get real ‘sciency’ for a moment: they do this by forcing the flame to try vaporising the water instead of the fuel. If the fire is doing this, it loses the energy it would spend on heating the fuel, and eventually dissipates.
Powder now. Perhaps the most versatile extinguishant there is (especially if we’re talking about ABC powder). Powder extinguishers suffocate the fires by creating a barrier between the fuel and oxygen. You can imagine how this works for Class As: the substance is covered in powder, so it’s not touching air.
And then, finally, foam. While foam extinguishers are primarily used for Class B fires, their impressive versatility allows for As and Cs as well. Functionally, it’s like a hybrid of water and powder. It smothers to fuel source, creating a barrier like how powder does. But the foam is also a cooling agent, removing heat from the fuel source directly, much like water.
Water Extinguishers, the Best for Class A Fires (but nothing else)
If you’re thinking that you can use water on any kind of fire… don’t, just don’t. Film, TV, and the News might have taught you that it would make sense to. After all, firefighters spray water all over those burning buildings, or over those forest fires. Those are big fires, and getting a lot of water is easier than getting a lot of most other things. But if you try spraying water onto a petrol fire, you’re just going to spread all of that fuel around and then you will have a big fire on your hands.
But let’s be more forgiving to water extinguishers for a moment. You may wonder, as I have, what makes water better than any other extinguishant. They definitely seem quite limited, using a simple substance that is only really suitable for one fire classification. And that’s true, but they are genuinely better at dealing with Class A fires than other types. Firstly, it’s fair to commend water for its straightforwardness. Water extinguishers are simple, decisive, no-nonsense Class A fire killers and sometimes, simple is best. If you want a more reasoned case for water extinguishers though, I can do that too.
We’ve already talked about how water diverts the fire’s energy toward trying to vaporise it, which creates steam. This means that the water is absorbing the thermal energy, and it does so very quickly. The water penetrates the burning material, eventually providing complete and total cooling of the fuel substance. Other extinguishants, like foam and powder, either penetrate the material less, or not at all. This means they can leave hot spots, leaving a chance, however small, of reignition that water simply doesn’t.
The Roundup
So, to tie it all together: Class A fires are fires involving carbon-based solids like wood and textiles. You can use water, foam, and powder extinguishers on Class A fires, but NOT CO2 extinguishers. Water is particularly good against them because it soaks through the fuel source, removing heat from the fire triangle.
Hopefully you now have an idea of the abundance of Class A fires, how to prevent them, and the best ways to tackle them if they do occur. If you have a need to secure yourself or your property against Class A fires then feel free to browse our wide range of fire extinguishers here, or focus your search a bit more onto our water extinguishers specifically here.
And in the meantime, if you want a more thorough explanation of our Water Fire Extinguishers, then check out this helpful video:
