Understanding Fire Classes and Fire Extinguishers
Fires can be extremely dangerous and cause immense damage if not addressed quickly and properly.
That’s why it’s crucial to understand the different types or classes of fires, and how to select the right fire extinguisher for each situation.
This comprehensive guide breaks down the various fire classes, the most common fuels and materials in each class, and the appropriate fire extinguishers to use for maximum safety and effectiveness.
The 5 Fire Classes
Fires are categorized into the following classes based on the type of fuel:
Class A Fires
Class A fires involve ordinary combustible materials such as:
- Wood
- Paper
- Cloth
- Trash
- Plastics
Class A fuels are extremely common. This is why having ABC fire extinguishers on hand is so important, as they can combat this widespread class of fire.
Class B Fires
Class B fires involve flammable or combustible liquids/gasses such as:
- Gasoline
- Alcohol
- Oil and grease products
- Paint
- Solvents
- Propane
- Kerosene
Class C Fires
Class C fires involve energized electrical equipment such as:
- Wiring
- Fuse boxes
- Circuit breakers
- Machinery
- Appliances
- Outlets
Class D Fires
Class D fires involve combustible metals such as:
- Magnesium
- Titanium
- Potassium
- Sodium
These types of fires rarely occur outside industrial settings. Dry powder extinguishers are typically required for Class D fires.
Class K Fires
Class K fires involve cooking oils and greases such as:
- Vegetable oils
- Animal fat
These fires most commonly occur in restaurant and catering kitchens. Wet chemical fire extinguishers are specially designed for Class K fires.
Selecting the Right Fire Extinguisher
It’s extremely important to use the correct type of fire extinguisher for the specific class of fire. Using the wrong extinguisher can make the fire worse and spread rapidly.
The chart below summarizes the right types of fire extinguishers for each class:
| Fire Class | Type of Fire Extinguisher |
|---|---|
| Class A | Water, Foam, Dry Chemical, Wet Chemical |
| Class B | Foam, CO2, Dry Chemical, Clean Agents |
| Class C | CO2, Dry Chemical, Clean Agents |
| Class D | Dry Powder |
| Class K | Wet Chemical, Dry Chemical |
Here is more detail on the most common extinguisher types:
Water Extinguishers
(Type A) are suitable for Class A fires only. They should not be used on grease or electrical fires.
Foam Extinguishers
(Type AFFF) can be used safely on Class A and B fires. They coat the fuel with a blanket of foam to remove oxygen.
CO2 Extinguishers
(Type BC) are effective on Class B and C fires. The carbon dioxide displaces oxygen and smothers the fire.
Dry Chemical Extinguishers
(Type ABC) are multipurpose extinguishers that can be used on Class A, B and C fires. The powder interrupts the chemical reaction and extinguishes the fire.
Wet Chemical Extinguishers
(Type K) are designed for commercial kitchens and specifically used for Class K fires involving vegetable oils and animal fats
Clean Agent Extinguishers
These extinguishers contain pressurized gas that won’t damage delicate electronics. Used for Class C and Class B fires.
Dry Powder Extinguishers
(Type D) are specially formulated to extinguish combustible metals in Class D fires.
Key Extinguisher Features
When selecting a fire extinguisher, there are certain features and ratings to look for:
UL Rating
Verify the extinguisher meets quality and reliability standards.
Type Rating
Indicates the types of fires the extinguisher can be used on (Class A, B, C, D, K).
Operation
Models include pull pin, squeeze lever, push button, or cartridge operated. Select the type that will be most intuitive for employees to operate.
Pressure Gauge
Gauges indicate if the extinguisher is sufficiently pressurized and functional. It’s important to replace faulty extinguishers.
Range
The range refers to the distance the extinguishing agent can be thrown effectively, typically 15 feet. Consider the size and layout of your facility when determining needed range.
Size
Typical sizes are 1A:10B:C, 2A:10B:C, 3A:40B:C etc. The number before “A” is the extinguishing capacity for Class A fires. Higher numbers mean more extinguishing power. Each number represents 1 ¼ gallons of water. For instance,2A means the extinguisher is just as effective as 2 ½ gallons of water. 4A is equivalent to 5 gallons of water. The Class B size rating indicates the square footage the extinguisher can cover, so “10-B” would equal approximately 10 square feet of surface area.
Following proper selection, usage, and maintenance guidelines will help ensure fire extinguishers are ready to safely put out fires when needed.
Proper Use of Fire Extinguishers
Simply having fire extinguishers on site is not enough. Employees should be trained on how to properly operate them in an emergency.
To use a fire extinguisher, follow the PASS technique:
Pull The Pin
This will allow you to discharge the extinguisher.
Aim at the Base of the Fire
Get close enough for an effective shot, but not so close that you inhale smoke or vapors (6-8 feet away).
Squeeze the Handle
This releases the extinguishing agent. Releasing the handle will stop the discharge.
Sweep Side to Side
Sweep right to left or left to right (NO UP AND DOWN). Start at the front edge of the fire and sweep across it until it’s fully extinguished. Watch for reignition.
It’s also critical to know when not to attempt putting out a fire, such as:
- The fire is spreading rapidly beyond the point of control.
- You don’t have the appropriate type/size of extinguisher.
- The fire blocks your exit path.
- You have any doubt in your ability to successfully extinguish it.
In these cases, evacuate immediately and call emergency services 911.
Fire Extinguisher Training
All American Fire Protection provides comprehensive hands-on fire extinguisher training classes in Fayetteville, NC.
Our qualified instructors cover:
Fire triangle theory
Fire extinguisher parts and operation
PASS extinguishment technique
Fire classes and types of extinguishers
Employees will gain confidence in using extinguishers through live fire scenarios with non-toxic smoke machines and propane simulator props. (We do not offer live fire training).
We accommodate groups of any size, from 5 employees to over 100. Contact us today to schedule fire extinguisher training at your location.
Fire Extinguisher Maintenance
Fire extinguishers require routine inspections and maintenance to remain fully functional. The National Fire Protection Association (NFPA) outlines the following intervals:
Monthly
- Visually inspect extinguishers to check for damage, low pressure, and obstructions.
- Confirm gauges show adequate pressure.
- Verify pull pin and tamper seals are intact.
- Check that the extinguisher is in its designated location.
Annually
- Conduct a more thorough examination of extinguisher mechanical parts, extinguishing agent, and expulsion method.
- Inspect the hose and nozzle for damage or blockages.
- Check the manufacturer’s recommended pressure.
- Clean extinguishers up.
- Replace components or entire extinguishers that fail examination.
Every 6 Years
- Perform maintenance procedures for the internal inspection.
- Recharge the extinguisher and verify performance. Replace unrepairable units.
When Used
- Immediately recharge extinguishers after any use.
When Purchased
- Record the date of purchase on the extinguisher.
Following this comprehensive maintenance routine will keep fire extinguishers in optimal operating condition. Contact All American Fire Protection in Fayetteville, NC to handle all of your fire extinguisher inspection, testing, recharging, and maintenance needs. We service all types and brands.
Rely on our expert technicians to help protect your business and employees. Call today at (910) 496-0600 for your free quote on our complete fire protection services.
Frequently Asked Questions About Fire Extinguishers
What types of extinguishers do you inspect?
We inspect all types of portable and wheeled fire extinguishers including water, foam, dry chemical, CO2, clean agent, and wet chemical extinguishers. No matter what brand or size, we can perform maintenance services.
What chemicals are used in a fire extinguisher?
Different chemicals are used for each different type of fire. Dry chemical extinguishers use a powder-based agent which prevents chemical reactions involving heat, oxygen and fuel, this extinguishes the fire. The substances used for this are Monoammonium phosphate, sodium bicarbonate, potassium bicarbonate, potassium chloride and sodium bicarbonate based dry chemical (Foam compatible).
Foam extinguishers use an aqueous film-forming foam, alcohol-resistant foams, film-forming fluoroprotein and a compressed air foam system. These smother the fires and prevent oxygen from fuelling it.
Water extinguishers use water to cool the burning material. This can be pump type water, air pressurized water and water mist.
Wet chemical and water additives extinguish a fire by forming a soapy foam blanket over burning oil and cooling the oil down below its ignition temperature. They use wetting agents, antifreeze and a loaded stream (an alkali metal salt solution which when added to water lowers its freezing point).
Carbon Dioxide extinguishers put out fires by displacing oxygen and removing heat from the combustion zone. They use halocarbon replacements, CO2, novec 1230, potassium aerosol and E-36 cryotec.
Watermist – there are no chemicals in the water mist extinguisher, it does, however, contain de-ionized water. The fine spray from the unique misting nozzle provides safety from electrical shock, greatly enhances the cooling and soaking characteristics of the agent and reduces scattering of burning materials.making them the best extinguishers for protection of hospital environments, telecommunication facilities and “clean room” manufacturing facilities.
My tags are expired; what do I do now?
It’s important to get expired fire extinguishers inspected and recharged immediately. We recommend replacing extinguishers over 6 years old. Contact us to schedule an inspection ASAP to help get your fire extinguishers compliant.
What happens if you use the wrong fire extinguisher?
Using the wrong extinguisher could make matters worse; water on an oil/electric fire would cause the fire to get bigger. It’s safer to make sure you use the correct extinguisher.
Where should I place my fire extinguisher?
Fire extinguishers should be visible, accessible, and near exit routes. They are best mounted to a wall bracket at a height between 3-5 feet above the floor. Avoid placing extinguishers behind furniture or equipment that could block access.
How often should I inspect my fire extinguisher?
Fire extinguishers should be inspected monthly to verify they are pressurized, undamaged, unobstructed, and operable. Professional annual inspections are also required.
What type of fire extinguisher do I need?
The type of extinguisher needed depends on the classes of fire you need protection from. For example, offices and homes will typically require a multi-purpose ABC extinguisher for solid combustibles, liquids, and electrical fires. Commercial kitchens need Class K wet chemical extinguishers designed specifically for grease fires.
When should I hydrotest my fire extinguisher?
Hydrostatic testing is recommended every 5-12 years depending on the type, to check for leaks and ensure the cylinder integrity is sound. CO2 extinguishers require testing every 5 years. We can perform hydrotesting to NFPA standards at our shop.
How do I properly dispose of old fire extinguishers?
Don’t throw old fire extinguishers in the trash. The pressurized contents require special handling. Contact us for guidance on proper disposal – we will safely decommission and recycle expired units. This also applies to any partially or fully discharged extinguishers.
Do you sell new fire extinguishers?
Yes, we offer a full range of new UL-rated fire extinguishers for commercial, industrial, and residential needs. We carry popular brands and types like Ansul Sentry dry chemical extinguishers, Badger wet chemical and CO2 models, and Amerex clean agent extinguishers.
Do you refill CO2 tanks?
Yes, we can handle CO2 tank refills for a variety of applications including paintball tanks, personal CO2 cylinders, sodastream cylinders, kegerator CO2 tanks, and high capacity CO2 tanks. Our trained technicians will safely inspect, test, and refill your tank.
Do you inspect fire extinguishers at your office? Can I bring my fire extinguishers to you to be inspected or recharged?
Absolutely – we have a shop at our office in Fayetteville, NC where we perform inspections, maintenance, recharging, hydrostatic testing, and other services for all types of fire extinguishers. Customers are welcome to drop off their extinguishers with us for reliable service and quick turnaround.
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Within 24 hours we will setup an appointment for your free on-site safety survey to see how we can help protect your business.