Now when people think about fire extinguishers it is virtually always the water based models that come to mind. This is because it is such a good extinguishing agent and has been used to tackle fires for thousands of years. In fact since mankind first discovered fire it has been water that is the primary fire fighting medium. I bet when that first human discovered how to start a fire he or she quickly worked out how to put it out fast. I can just picture them in a cave thinking oops, this fire thingy is a bit out of control and finding the nearest hollowed out piece of wood with water in to pour over it.
The drawback of a water extinguisher these days is the fact they can only be used on a Class A fire involving materials such as paper, fabric or wood. In today's modern world with electrical equipment, flammable liquids, oils and a full host of other combustible materials it makes their usage quite limited. Saying this though, they are still one of the most commonly seen and sold models on the market worldwide.
Water extinguishers are a solid red colour so easily identifiable when it comes to recognising one in an emergency. Other types such as CO2 or powder have coloured panels to clearly mark what type they are.
One reason water is still so commonly used in offices and homes is the fact that they are simple to operate and completely harmless to the environment. So a good option is going green is a concern for you. If you accidently set off a powder or foam model you know you will be in for a complete mess, but with water all you get is your own mini pond on the floor. A quick mop-up and its all cleaned up. This is probably why they are so commonly seen in schools and colleges where the odd naughty student may set one off for a laugh.
As we stated earlier, you can only use water on Class A fires. This is because they can be dangerous to use on other types of fire. Water is conductive so spray it on an electrical fire and it may not be the fire that actually kills you. Also, just imagine what would happen if you sprayed one on a cooking fat fire such as in a deep fat fryer. The fire would explode and that's not a good thing. On other classes such as Class B or D the water would spread the burning materials around and thus cause the fire to spread quickly and become a serious hazard to property and life. This is why they are often paired with CO2 or other models so as to provide effective coverage in any situation.
Now how exactly does a water extinguisher work? Well it's simple really. There are two basic elements to its operation as a fire fighting medium. The water helps to cool the fire as it evaporates on contact and also soaks the materials preventing them from burning. As is well known, water is not exactly the type of material to burn. They normally come in 9 litre variants and as such are quite heavy in comparison to say a 6 litre foam model. The standard fire rating on a water extinguisher is 13A with some coming in at 21A.
You can also get them in what's called water additive models but we will explain those in another fact guide.
