Author Topic: Fire Extinguisher Class Rating and Information  (Read 5153 times)


  • Hero Member
  • ****
  • Posts: 782
  • PA Jeeps-Vice President
    • View Profile
Fire Extinguisher Class Rating and Information
« on: September 20, 2006, 07:14:52 pm »
                    Fire Extinguisher Information
 Please take a few minutes to read this information and become familiar with the extinguishers in your home and/or rig. Also note that your typical multi-class powder type extinguisher are usually good for six years, the powder settles and becomes caked at the base rendering it less effective. Please keep your equipment up to date.
Fire Extinguisher specifics and class ratings.
  Class "A" fires: Paper, wood, trash, rubber and some plastics.
  Class "B" fires: Flammable liquids such as gasoline, oil, diesel fuel, paint thinners etc.
  Class "C" fires: Energized electrical fires.
  Class "D" fires: Flammable metals such as magnesium and titanium.
Fire extinguishers can be rated class specific or multi-class. Only use extinguishers on fires that the extinguisher is rated for!
  Class "A" extinguishers are normally pressurized water and should only be used on class "A" material. If applied to burning liquid (class B) or energized electrical (class C) serious injury and a larger fire can occur. Class "D" material probably won't be extinguished.
  Class "B" extinguishers may contain a powder, foam or gas (co2 or halon). Do not use class "B" foam on electrical fires.
  Class "C" extinguishers may contain powder or gas (co2 or halon).
  Class "D" extinguishers may be metal specific, different metals may require a different extinguishing agent.
Multi-Class extinguishers
  Class B, C may contain powder or gas (co2 or halon) and can obviously be used on flammable liquids and electrically energized fires.
  Class A, B, C may contain powder or gas (co2 or halon). Self explanatory.
Numerical ratings:
  Class "A" and class "B" Extinguishers will also have a numerical rating associated with them. Class "C" and "D" does not.
  Class "A" numbers are relevant to the amount of water the extinguisher holds. A rating of 40A holds a much larger volume of agent than a 1A.
  Class "B" numbers refer to the square footage of fire that can be extinguished. A rating of 10B will extinguished twice as much area as a 5B.
 In closing, please be aware that powder type extinguishers are very corrosive to electrical wiring, connections, circuit boards, computers etc. To avoid this problem co2 and halon gas extinguishers are recommended. Co2 extinguishers are a little costly and should be purchased in 5lb and up sizes. Halon is also expensive and can be purchased in a 2.5 lb and up. A 2.5lb halon is usually a 1A,5B,C. The reason for wanting a larger co2 or halon extinguisher is the fact that they are a gaseous agent that starves the fire of oxygen while cooling the air and does not smother it like powder or foam. Gas agents are easily displaced by wind.
Thanks for your time,

Charlie Stevens

« Last Edit: January 31, 2012, 11:36:12 am by Rick_Bear »
Charlie "The Tuna" Stevens
2004 Wrangler Sport-4 1/2" BDS Suspension, 1 1/4" JKS Body Lift with 35" BFG's