You Asked and We Heard! Here’s more on Types of Fire Extinguishers.
We’ve received quite a few requests to delve deeper into the types of fire extinguishers. If you missed our previous post, you should check out, “Choosing the Right Fire Extinguisher,” for an overview of the basic extinguisher types. We will feature specifics of each time monthly, until we run out of content or you tell us to stop.
Summarizing Foam Extinguishers
Foam extinguishers come in 2 forms: aqueous film-forming foam (AFFF) and film-forming fluoroprotein foam (FFFP). AFFF and FFFP are appropriate choices for class A and B fires. Don’t forget, class A is for regular combustibles like paper and class B is for flammable liquids like gasoline.
When Will I Use a Foam Extinguisher?
In class A fires, the foam works as a coolant to reduce the temperatures below the ignition level. Foam extinguishers work especially well for class B fires where there are horizontal flammable liquid situations such as oil on water. The agent will float on top of the liquid, suffocating the flames and preventing reignition.
Word of Caution
Keep in mind, foam extinguishers are not suitable to use on pressurized fuel fires or cooking grease fires. Additionally, only some grades of foam extinguishers protect against water-soluble flammable liquids like alcohol. The nameplates on the extinguishers will provide more specific information.
Foam type extinguishers should not be used in freezing temperatures. NFPA 10 forbids mixing antifreeze with the foam agents, so a compliant foam extinguisher will not work in -40 degree weather. The exception to this rule is if the manufacturer provides special measures to prevent the agent from freezing.
AFFF and FFFP foam fire extinguisher present a shock hazard if used on fires involving energized electrical equipment.
Visit the NFPA website here for even more specifics. The content in this post was taken directly from NFPA 10.
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