There are three things that must be present in adequate quantities for a fire to burn. First, you need a fuel source, for example, paper, wood, fabric, plastic, paint thinr or grease. Secondly, oxygen must be present in sufficient quantity to support the combustion process. And third, a heat source is required to raise the temperature of the material to the point where it will ignite. And by removing one of these three combustion “ingredients,” you can put out the fire.
There are a variety of portable extinguishers that work in different ways to extinguish a small fire. A portable type fire extinguisher is a container filled with water and pressurized with compressed air. The water is discharged onto the fire, which in turn cools the combustion material below its ignition temperature. Water extinguishers work well in Class A fires involving ordinary fuels such as paper, wood, fabric, and many plastics, but should never be used in flammable liquid fires or Class B fuels. This is because the oil and water do not mix, so the water actually “carries” the liquid on fire and causes it to spread. And you should never spray water in a class C fire involving energized electrical equipment, for obvious reasons.
Fire extinguishers filled with carbon dioxide (CO2) gas work by flooding the fire area with the gas, which displaces the oxygen the fire needs to burn. These type extinguishers work well in class B fires involving flammable liquids and fuels, but caution should be exercised if used in small, tightly enclosed spaces, as they could also displace the oxygen you need to breathe. Fire extinguishers filled with a fine inert powder pressurized with nitrogen, often called “Dry Chemicals” extinguishers, work by “suffocating” the fire, just as throwing a blanket over a small fire can also quell it. These “combination” extinguishers are typically classified for Class A and B fires, as well as Class C electrical fires, and are the type most often seen in workplaces. While these are just three of the various portable type extinguishers available to extinguish small fires, they are some of the most widely used.
All portable fire extinguishers are labeled to let you know exactly what kind, or classes, of fire are suitable for extinguishing. So take some time to look at the labels of portable fire extinguishers located in your work areas, as well as the ones you may have in your homes, to make sure you’re familiar with the type of fires that should, and shouldn’t, be used to extinguish. And if there are any questions about the types of fire extinguishers available in your workspace, contact your safety manager or supervisor for additional guidance. Does anyone have any questions or comments about the types of portable extinguishers that are best suited to extinguish different types of fires.
courtesy of www.oshatraining.com.