Knowing the Difference between Foam and Powder Fire Extinguishers

Most people know the basics about fire extinguishers. For instance many people know that water-based extinguishers are best used for putting out fires involving solid combustibles like wood, paper and fabric and shouldn’t be utilised anywhere near electrics (unless they contain an additive). Similarly, most people also know that Carbon Dioxide extinguishers can be used to great effect on electrics as well as petrol, oil and solvents.

However, the area where people tend to get confused is with foam and powder extinguishers.

Hopefully, this brief outline of the various attributes and applications of foam and power extinguishers will help to clear up any confusion.

Foam extinguishers
Foam extinguishers are good to have in homes and offices as they are suitable for use on class A solid combustible fires (wood, paper, upholstery) and class B flammable liquid fires (petrol, liquefying plastic, paints). As a rule, foam extinguishers are not to be used on chip pan fires or gas fires.

These extinguishers work by forming a blanket of foam on the burning material, thereby starving a fire of fuel (oxygen). Indeed, the dispersed foam also penetrates deep into burning materials so that it can extinguish deep rooted embers. In addition, the water content of the foam evaporates in the heat and cools the fire down to prevent any risk of re-ignition.

Although dispersed foam presents no immediate risk regarding inhalation, it should be cleaned up as swiftly as possible after dispersal, as the AFFF foams are carcinogenic. Thankfully, the jets on foam extinguishers are able to target relatively small areas therefore most areas are usually quite easy to clean up after dispersal.

Powder extinguishers
Powder extinguishers are the most versatile extinguishers available. Indeed, as well as being suitable for use on class A and B class fires, powder extinguishers can also be used on class C fires (caused by combustion of gasses such as natural gas, propane, hydrogen) and on live electrical equipment. This versatility makes powder extinguishers well-suited to broad range of environments such as workshops, cars, boats and even some homes.

Powder fire extinguishers are more powerful than foam extinguishers; therefore, they are typically smaller than their foam counterparts. Instead of soaking into a burning material, however, powder extinguishers work by forming a crust-like blanket which is able to effectively starve a fire of fuel.

Dispersed powder can be inhaled and therefore care must be taken when it is sprayed. In addition, these types of extinguishers tend to leave a lot of residue behind so there is sometimes a degree of hesitation before powder extinguishers are used within buildings.

Fire Extinguishers Explained

Fire safety training will give you and your employees information about fire protection equipment and when it should be used. One of the most important things to understand are the different fire extinguishers that are available, as using the wrong one could create just as many problems as the fire itself.

There are five different classes of fire risks: A, B, C, D, F. Each class describes a different kind of fire and the fire extinguisher will be clearly labelled with the risk classes they are able to fight. If you are buying fire extinguishers for your property, but are unsure which one you need to install in which areas, then our extinguisher guide should provide you with everything you need to know. Our friendly staff will also be more than happy to help.

Class A: solids such as paper and wood
Class B: liquid fires such as burning petrol (not fat)
Class C: gas fires
Class D: burning metal such as magnesium
Class F: fat fires and deep fat fryer fires

The classes stated on the extinguisher also have a number next to them. The higher the number, the better the fire fighting capability of the extinguisher in this class.

Water extinguishers (colour coded red) are the most widely used and are used on solids such as paper, wood or fabrics. They should not be used on electrical equipment unless they contain an additive. Offices and reception areas are usually equipped with foam extinguishers (cream colour coding) and CO2 extinguishers (colour coded black). CO2 extinguishers will not damage the electrical equipment.

If your building has a kitchen, this will need a wet chemical or an ABF fire extinguisher to deal with fat fires. Other areas with greater fire hazards, such as laboratories, may require powder (coded blue), metal or CO2 fire extinguishers as appropriate depending on the risks involved. Powder extinguishers can be used on solids, flammable liquids or gases.