Fire Extinguishers: Understanding Types and Fire Classes

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.Extinguishers suitable for Class A fires include water, foam, dry chemical, and wet chemical extinguishers.

Class B Fires

Class B fires involve flammable or combustible liquids/gasses such as:

Gasoline
Alcohol
Oil and grease products
Paint
Solvents
Propane
Kerosene

These fires can spread quickly and pose a significant risk. To effectively extinguish Class B fires, use foam, CO2, dry chemical, or clean agent fire extinguishers. These extinguishers work by smothering the fire, removing oxygen, or interrupting the chemical reaction.

Class C Fires

Class C fires involve energized electrical equipment such as:

Wiring
Fuse boxes
Circuit breakers
Machinery
Appliances
Outlets

These fires can be particularly hazardous due to the risk of electric shock, making it crucial to use non-conductive extinguishing agents.

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

Living Areas and Bedrooms: Install multipurpose dry chemical extinguishers (rated for Class A, B, and C fires) in easily accessible locations, such as near exits or in high-traffic areas.

Kitchen: Use a wet chemical extinguisher (Class K) specifically designed for cooking oil and grease fires. Avoid using water or regular dry chemical extinguishers, as they can splatter the burning oil and spread the fire.

Garage and Workshops: Choose a larger multipurpose dry chemical extinguisher (Class A, B, and C) to handle potential fires involving flammable liquids, solvents, or electrical equipment commonly found in these areas.

Consider additional extinguishers for other high-risk areas, such as near fireplaces, heating appliances, or electrical panels. Ensure that all family members know the location of the extinguishers and how to use them properly.

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

Suitable for Class A fires only. They should not be used on grease fires or electrical fires, as water can spread the fire or cause electrocution.

Foam Extinguishers

(Type AFFF) Effective on Class A and B fires. They coat the fuel with a foam blanket, removing oxygen and extinguishing the fire.

CO2 Extinguishers

Designed for Class B and C fires. The carbon dioxide displaces oxygen, smothering the fire without leaving a residue. However, they are not suitable for confined spaces due to the risk of asphyxiation.

Dry Chemical Extinguishers

Multipurpose extinguishers that can handle Class A, B, and C fires. The powder interrupts the chemical reaction, extinguishing the fire quickly. However, the residue can cause damage to electrical equipment.

Wet Chemical Extinguishers

Specifically designed for Class K fires involving cooking oils and fats. They work by forming a soapy foam that cools the fire and prevents re-ignition.

Clean Agent Extinguishers

Suitable for Class B and C fires, particularly in areas with sensitive electronic equipment. They use pressurized gas to extinguish fires without leaving a residue or damaging electronics.

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:

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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.

Schedule A Training

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.

How often should I replace my fire extinguishers?

Fire extinguishers should be replaced every 5-15 years, depending on the type and manufacturer’s recommendations. Disposable extinguishers should be replaced after each use, while rechargeable ones can be serviced and reused if in good condition. Check the pressure gauge monthly and have the extinguisher professionally inspected annually to ensure it is in proper working order.

Can I use any type of fire extinguisher on an electrical fire?

No, it is crucial to use the correct type of fire extinguisher for electrical fires (Class C). CO2, dry chemical, and clean agent extinguishers are suitable for extinguishing fires involving energized electrical equipment. Never use water or foam extinguishers on electrical fires, as they can cause electrocution and worsen the fire.

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.

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.

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.

Get Your Free Safety Survey

Within 24 hours we will setup an appointment for your free on-site safety survey to see how we can help protect your business.

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