Fire Extinguishers: What you need to know

October 28, 2021

Fire Safety Month is coming to a close and we’d be remiss if we didn’t address fire extinguishers. If your first line of defense at fire prevention is a fire alarm then your second line is a portable fire extinguisher.

Catching a fire before it spreads can be the difference between things going from bad to worse. We’re offering a way to keep it simple by using our blog as your guide for all things fire extinguishers.


Fire Classifications

Deciding which fire extinguisher(s) to have in your home and/or business is determined by the type of fire that can potentially occur in any given location. Or, said another way, the type or “class” of fire determines which fire extinguisher should be used.

Class of Fire

  • Class A Fires
    • Fires in ordinary combustible materials, such as wood, cloth, paper, rubber, and many plastics.
  • Class B Fires
    • Fires in flammable liquids, combustible liquids, petroleum greases, tars, oils, oil-based paints, solvents, lacquers, alcohols, and flammable gases.
  • Class C Fires
    • Fires that involve energized electrical equipment.
  • Class D Fires
    • Fires in combustible metals, such as magnesium, titanium, zirconium, sodium, lithium, and potassium.
  • Class K Fires
    • Fires in cooking appliances that involve combustible cooking media (vegetable or animal oils and fats).


Extinguishing Agents

The extinguishing agent (the material inside the extinguisher that is sprayed onto the fire) is what differentiates one fire extinguisher from another. Below are the types of extinguishing agents.

Water – used in operating rooms, museums, and libraries. Not suitable for freezing temps unless antifreeze is used

Film-Forming Foam Types (AFFF and FFFP) – Rated for Class A & B fires. Not suitable for freezing temps.

Carbon Dioxide (CO2) – Rated for Class B & C fires. Best for areas with a lot of electronic equipment, food preparation, labs, and printing areas.

Halogenated Agent Types

Halon – Rated for Class A, B, and C fires (select larger models). Similar to CO2 (bromochlorodifluoromethane (Halon 1211))but can be used in cold weather. Phased out due to environmental damage to the ozone.

Halon Alternative Clean Agents – Rated for A, B, and C fires (larger models) with twice the range of CO2. Not detrimental to the ozone layer.

Dry Chemical Types

Ordinary Dry Chemical – Rated for Class B & C fires. Using powders such as sodium bicarbonate or potassium bicarbonate.

Multipurpose Dry Chemical – Rated for Class A fires and uses an ammonium phosphate bae agent. Not ideal for deep-seated fires.

Wet Chemical – Rated for Class A and K fires. water and potassium acetate, potassium carbonate, potassium citrate, or a combination of these chemicals (which are conductors of electricity).

Dry Powder Types – Rated for Class D fires and specific metals. This agent can also be applied using a hand-propelled fire extinguisher (scoop and shovel).


Fire Inspections

Keep your extinguishers reliable and effective with regular fire inspections. We provide complete fire extinguisher inspections as required by NFPA 10*: monthly inspections, annual maintenance, twelve-year hydrostatic tests (where required), and six-year maintenance. Most necessary fire extinguisher recharges or repairs can be done right on-site by one of our certified professionals. We make recommendations to ensure your facility is protected with the appropriate sizes and types.

Minimum Inspection Procedures:

  • Make sure it is located in its designated place
  • Make sure the extinguisher is visible or that there is signage indicating where the extinguisher is located
  • Make sure you can easily access the extinguisher
  • Ensure the pressure gauge is in the operable range or position
  • Make sure it is full, this can be done by just lifting the extinguisher or you can weigh it
  • For wheeled extinguishers, make sure the condition of tires, wheels, carriage, hose, and nozzle are acceptable
  • For non-rechargeable extinguishers, operate the push-to-test pressure indicators

As your trusted consultant, we also offer you and your staff fire extinguisher safety and proper use training. It’s our hope that your fire extinguishers will never be needed, but it’s our job to ensure you are fully prepared for all scenarios.

*NFPA 10 provides requirements to ensure that portable fire extinguishers will work as intended to provide your first line of defense against fires of limited size.


Business Fire Extinguisher Placement

Brian O’Connor, who writes for the National Fire Protection Agency (NFPA) states, “In my humble opinion portable fire extinguisher distribution and placement is the trickiest part of the installation. There is a balance between efficiency and practicality that truly makes a difference in the event of an emergency.” He also references the NFPA 10 which addresses “maximum travel distance to the extinguisher,” as indicated in the table below.

NFPA Travel Distance Chart

For detailed measurement information, visit

The NFPA has a detailed fire extinguisher placement guide, however, Per Mar can alleviate this task for you. It’s a delicate balance between how they should be distributed and where placement is allowed. You also want to ensure you purchase enough extinguishers to be conveniently placed but not so many to break the bank (both in cost and maintenance).

Always place your fire extinguishers along the normal path of travel (think accessible during evacuation) but also away from any potential obstructions. Depending on your extinguisher size, it’ll either be 4 in. to 5 ft. off the ground (<40 lbs) or 4 in. to 3.5 ft. off the ground (>40 lbs). They can be installed on intentional hangers or brackets and in cabinets.


Home Fire Extinguisher Types, Size & Placement

Class A, B, and C fires are most common residentially so a home fire extinguisher may be a combo of all three (A:B:C fights all three types of fires: ordinary combustibles, flammable liquids, and electrical). Residential fire extinguishers should be placed on each floor of your house.

Abbreviated sizing guide:

  • 10 pounds – garage, workshop
  • 5 pounds – kitchen or laundry room
  • 2 pound – car
  • Stove-top – range hood

How to use a fire extinguisher:

Remember the acronym PASS.





Pull the safety pin, aim at the source of the flames (rather than just the flames), squeeze and hold the trigger, and sweep the source until the extinguisher runs dry.

Lastly, don’t skip your family or workplace fire planning and practicing! There is a lot going on during this life-threatening event so having a practiced routine in place is imperative.

As always, please contact us for more information or for help inspecting or placing your fire extinguishers!