You may have seen letters marked on the side of a foam fire extinguisher or dry chemical extinguisher, but not known what these are for. Generally, fire extinguishers come in several different types, depending on the fires they're capable of addressing.

Some fires can actually be spread or made worse by the methods used to put other types out. For instance, you should never pour water on a grease fire, as it can actually move the burning oil to another location. Don't get electrical fires wet, because there's a risk of electrocution. Many foam fire extinguishers are certified for type A fires (combustibles like paper, wood, coal, and other normal fires), and type B fires (liquids like oil, spirits, or petrol, but not cooking oils). Most are not certified for type C fires (flammable gases) or for electrical fires. Use wet chemical extinguishers certified for type K fires on cooking oil and other kitchen fires.

Foam fire extinguishers, by comparison, contain a foam that forms a film rapidly. This knocks down flames and works like a fire blanket to smother the fire. The film on top of the foam seals in vapours and prevents the fire from getting oxygen, so that it can't reignite. All foam fire extinguishers are a good solution for situations where both class A and class B fires. They are less useful for type C fires, because they can't encapsulate burning gases as well.

The majority of ABC fire extinguishers are dry chemical types. The most common of these contains ammonium phosphate. Be careful using this type of extinguisher - it's potentially abrasive and corrosive. That means that the dry chemicals inside can damage some metals, like aluminium. In fact, the aluminium phosphate used in them sometimes undergoes hydrolysis, forming phosphoric acid and damaging materials it strikes. This is why this type of extinguisher isn't used on aircraft, and why you shouldn't use it on electronic devices unless there are no other extinguishers available.

When you use a fire extinguisher of any kind, the first step is to make sure that others are aware of the fire. Let people in the same building know, or call the fire department, before you attempt to tackle the fire on your own. Be certain that your head is clear of smoke and fumes, the cause of up to seventy percent of fire related deaths. Also, be absolutely sure you know how to use the extinguisher before attempting to put out the fire. Check the type of extinguisher you have to make certain that it's appropriate for the fire at hand. Never let the fire get between you and the exit from the room.

Once you know that everyone has been alerted, and you're safe, you can use the extinguisher. Only try to put out small fires that are just getting started. Larger ones are unsafe. Release the foam or ABC fire extinguisher's trigger by pulling the plastic tag out, and take firm hold of the hose. Lay a blanket of powder or foam on top of the area where the fire is to smother it. Remember that you can always leave the area if the extinguisher is exhausted or you're not sure about attempting to put the fire out on your own. Don't be tempted to walk or stand in an area where you've extinguished a fire, since it may reignite.

Using the right type of fire extinguisher is very important when you have to deal with a fire. Decide what sort of fire you have to put out, and use a foam fire extinguisher, ABC fire extinguisher, CO2 fire extinguisher or other model to help you deal with the fire. Always follow the safety and use instructions printed on the outside of the container. These types of extinguisher may be found in garages, factories, workplaces, and just about anywhere you might encounter a fire. Regular maintenance is important to make sure that your extinguisher functions properly. Always be as safe as possible around a fire. That means using the right extinguisher, making sure it's charged properly, and using it safely.