How Do Fire Extinguishers Work?

By Author: Ken mar fire Extinguisher company
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A fire extinguisher works to put out a fire because it removes one or more of the 3 essential elements of fire.
Foam and Water extinguisherTo maintain a fire you need HEAT, OXYGEN and FUEL.
Remove any one of these, and the fire will go out.

So for example a CO2 extingusher will put out a fire because it displaces the oxygen. An air-water extinguisher works because it cools the fuel, ie no heat. Dry chemical fire extinguishers and foam extinguishers work by separating the fuel from the oxygen. They form a film that covers the fuel and stops access to the oxygen. The extinguisher usually only provides a temporary solution, it is still important to ensure the rogue heat source is completely removed or cooled to prevent re-ignition.

Why are there different types of extinguishers?
Because there is more than one way to put out a fire, and because there are different fuels, and even different types of heat, that need different approaches to ensure the safety of the person trying to put out the fire. If you use the wrong type of extinguisher on a fire, you could make it worse, and/or put yourself in ...
... danger.

Consider electrical fires for example. The most important thing to do to stop one, is to turn off the electricity, thereby removing the heat source. This is not always easy to do, as the power switch is often too close to the item on fire. If you try to put it out with a water, or foam extinguisher, you run the risk of getting electrocuted because water could conduct the current to the user. The ideal fire extinguisher to use is a CO2 extinguisher. Not only can it get in around difficult-to-reach objects, but it also leaves no residue. However once the CO2 clears, the fire will re-ignite unless the cause of the fire has been fixed.

Water or AFFF (Foam) extinguishers must not be used on deep seated cooking oil/fat fires, when the water hits the hot oil it will convert to steam, with a possible violent ejection of burning fuel from the container. The blast from a CO2 extinguisher on a fat, or a petroleum fire could cause hot burning fuel to be spread widely.

A wet chemical fire extinguisher is ideal for oil and fat fires because it sprays a mist over the oil which chemically reacts to form "soap", thus providing a barrier between the hot fat and oxygen. As soon as the flames stop you must turn off the heat. Don't move the oil/fat until it has cooled- if the soap layer is disturbed it may re-ignite.

Dry chemical or ABE extinguishers work on the widest variety of fires by spraying a powder over the fuel. They go by various names; DCP- dry chemical powder, and ABE- referring to the fire types it can be used upon. The powder is derived from bird droppings (!) and works because the heat of the fire causes it to melt and form a film/layer over the fuel, cutting off its access to oxygen.