What Is A Class B Fire Extinguisher Used For: Features, Tips, and How To Use

In a world where fires can ignite with a flicker and rage with a vengeance, the need for effective firefighting tools becomes paramount. 

Among these indispensable tools stands the mighty Class B fire extinguisher, a sentinel of safety against flammable liquids and gases. 

What is a class B extinguisher used for? A Class B fire extinguisher is used for extinguishing fires involving flammable liquids and gases, such as gasoline, oil, solvents, and propane. The extinguisher works by smothering the flames and cutting off the oxygen supply.

Let’s dive into the remarkable world of the Class B fire extinguisher and unlock its life-saving secrets.

What Is A Class B Fire Extinguisher Used For

Features of Class B Extinguisher 

Designed to swiftly suppress these potentially hazardous fires, these extinguishers offer a potent combination of rapid action and versatile application. Here are the key features of Class B fire extinguishers:

Dry Chemical Agent: Class B fire extinguishers use dry chemical agents, such as monoammonium phosphate, sodium bicarbonate, or potassium bicarbonate, as their extinguishing agents.

Designed for Flammable Liquids and Gases: Class B fire extinguishers are specifically designed to tackle fires involving flammable liquids like gasoline, oil, alcohol, and flammable gases like propane and butane.

Effective Smothering Action: The dry chemical agent works by smothering the flames, creating a barrier between the fuel and the oxygen, which is essential for fire combustion.

Multipurpose Capabilities: Some Class B extinguishers may also be effective against Class C fires (involving electrical equipment), making them versatile in certain situations.

Rapid Fire Suppression: The dry chemical agent discharges rapidly, enabling quick suppression of the fire and preventing its spread.

Suitable for Outdoor and Indoor Use: Class B fire extinguishers are appropriate for various environments, including garages, kitchens, laboratories, and industrial settings.

Wide Range of Sizes and Capacities: These extinguishers are available in different sizes and capacities, ranging from portable handheld units to larger wheeled extinguishers for industrial use.

No Conductive Properties: The dry chemical agent in Class B extinguishers is non-conductive, meaning it can be used on small electrical fires (Class C) without posing an electrical shock hazard.

Different Types of Class B Fire Extinguishers

Now, let’s take a closer look at the various types of Class B fire and see which one is more suitable for you:

Class B Fire ExtinguishersExtinguishing AgentSuitable forUse Case
Dry Chemical Fire ExtinguishersMonoammonium phosphate, sodium bicarbonate, or potassium bicarbonateFlammable liquid and gas firesEffective for various flammable liquid and gas fires, versatile applications.
Carbon Dioxide (CO2) Fire ExtinguishersCarbon Dioxide (CO2) gasFlammable liquid and electrical fires (Class C)Ideal for electrical fires as they do not leave residue or damage equipment.
Foam Fire ExtinguishersAqueous film-forming foam (AFFF) or Alcohol-resistant aqueous film-forming foam (AR-AFFF)Flammable liquid firesSuitable for use on spills or pools of flammable liquids. The foam creates a barrier, preventing re-ignition.
Clean Agent (Halotron) Fire ExtinguishersHalotron agentFlammable liquid and gas firesEffective for sensitive electronic equipment and areas where cleanup after extinguishing is a concern.
Wet Chemical Fire ExtinguishersPotassium acetate-based solutionFlammable liquid and kitchen fires (Class K)Designed for kitchen fires involving cooking oils and fats. Creates a soapy layer to prevent re-flash.

How to Use a Class B Fire Extinguisher?

To use a Class B fire extinguisher effectively, follow these steps:

Assess the Situation: Ensure the extinguisher is appropriate for the type of fire (flammable liquid or gas) and that it’s in working condition.

Remember PASS: Pull the pin, Aim low at the base of the fire, Squeeze the handle to discharge the agent, and Sweep side-to-side.

Maintain Safe Distance: Stand 6 to 8 feet away from the flames to avoid heat and splattering liquids.

Watch for Re-Ignition: Stay vigilant even after extinguishing, as some fires may reignite.

Evacuate if Necessary: If the fire becomes uncontrollable or you are unsure, evacuate and call for professional help.

Seek Training: Obtain proper training on fire extinguisher usage to enhance your readiness in emergencies.

Can a Class B Fire Extinguisher also be used for Class C fires?

Class B fire extinguishers are designed to combat fires caused by flammable liquids and gases. However, they should not be used for Class C fires, which involve energized electrical equipment. Class C fires require extinguishers specifically designed for them to avoid the risk of electrical shock. This highlights the significance of class C fire extinguishers in ensuring the safety of both the individuals extinguishing the fire and the surrounding environment.

Tips for Using Class B Fire Extinguisher

Here are some important safety tips to keep in mind when handling a Type B fire extinguisher:

Know the Fire Extinguisher Type: Familiarize yourself with the Class B fire extinguisher’s type and the specific extinguishing agent it contains. 

Maintain Adequate Distance: When using a fire extinguisher, maintain a safe distance from the fire. Stand at a distance of about 6 to 8 feet away from the flames.

Aim at the Base of the Fire: Point the nozzle of the extinguisher at the base of the flames, not the top. This directs the extinguishing agent where it can effectively interrupt the fire’s fuel source.

Sweeping Motion: Use a side-to-side sweeping motion while discharging the extinguisher. This technique ensures the extinguishing agent covers the entire fire area evenly.

Back-Up Plan: Always have an escape route and ensure you are not trapping yourself between the fire and an exit. If the fire becomes too intense or out of control, evacuate immediately and call for professional help.

Watch for Re-Ignition: Even after extinguishing the fire, keep an eye on the area for potential re-ignition. Some flammable liquids may reignite after cooling down, so remain cautious.

Proper Ventilation: Use Class B extinguishers in well-ventilated areas to prevent the accumulation of flammable vapors.


Class B fire extinguishers serve as indispensable tools in the battle against fires involving flammable liquids and gases. 

With their rapid and effective action, these extinguishers play a vital role in safeguarding lives and property.