How to Determine Fire Extinguisher Sizes

Brad Chacos

Portable fire extinguishers can mean the difference between an embarrassing, easily handled flare-up and the complete loss of your home. Fires spring up unexpectedly -- from cooking grease, dropped cigarettes, faulty wiring and many other sources -- and different types of fire extinguishers put out fires from different sources. An "A"-rated fire extinguisher puts out ordinary combustible materials, "B"-rated extinguishers combat flammable liquids and "C"-class extinguishers fight electrical fire. Larger rooms or rooms with a significant chance of a fire need either a larger or more potent fire extinguisher. All the information you need to purchase a fire extinguisher can be found on its label.

Select an ABC-rated extinguisher for home use.
  1. Examine your home and decide your fire extinguisher needs. "This Old House" recommends keeping a 2-pound extinguisher in cars, a 5-pound extinguisher in kitchen or laundry rooms, and a full 10-pound extinguisher in garages and workshops.

  2. Check out the fire extinguishers at a home supply store. Inspect the label on the outside of the fire extinguisher to determine the weight of the fire extinguisher when full. Lift the extinguisher to determine whether the extinguisher is too heavy for you to use effectively.

  3. Look for the number next to the extinguisher's A and B ratings. A higher number means that extinguisher is more effective against that type of fire. If you feel that a 5-pound or 10-pound extinguisher is too heavy for you to use effectively, select a smaller extinguisher with more potent firefighting materials.

  4. Weigh carbon-dioxide extinguishers to determine how much of the gas remains inside after using it. Carbon-dioxide extinguishers can't use a pressure gauge like other types of extinguishers due to the nature of the chemical, so they stamp the weight of the empty container on the outside of the extinguisher. Weigh the extinguisher and subtract the weight of the container to determine how much carbon dioxide remains inside.