types of fire extinguisher, which extinguisher is used for electrical fires

How to Choose The Right Fire Extinguisher

Fire extinguishers are the first line of defense against a potentially devastating fire. But with a vast array of extinguisher types and classifications, navigating this crucial line of defense can feel like deciphering a foreign language. 

This guide will help you to confidently navigate the types of fire extinguishers by demystifying fire classifications, exploring extinguisher functionalities, and providing valuable insights into choosing the right extinguisher for your specific needs.

By understanding the types of fires you might encounter and the extinguishers designed to combat them, you can be one step closer to safeguarding your surroundings and empower yourself to take control in an emergency situation.

Imagine your home – a haven of warmth, comfort, and cherished memories. Now imagine a fire erupting within its walls, and with your loved ones present. Maybe even a child or two. 

The right fire extinguisher, strategically placed and understood by household members, can make all the difference in containing a small blaze before it spirals into devastating chaos. 

The same principle applies to workplaces, businesses, and industrial settings. Equipping yourself with fire extinguisher knowledge empowers you to respond effectively in those critical moments, safeguarding lives, property, and business continuity.

In this guide, we will be looking at:

  • What type of fire extinguisher do you need?
  • What are the 4 types of fire extinguisher?
  • What’s inside a fire extinguisher?
  • How does a fire extinguisher work?
  • Do fire extinguishers expire?
  • How to inspect a fire extinguisher?
  • How to recharge a fire extinguisher?
  • How to dispose of old fire extinguishers?
  • What does the number on a fire extinguisher mean?
  • Which extinguisher is used for electrical fires?
  • How to extinguish a grease fire?

At Indiana Alarm, We’re #InThisTogether. We repair, service and inspect fire extinguishers. Contact us today for a free quote

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Understanding Fire Classes: What Type Of Fire Extinguisher Do Your Fire Need?

Fire extinguishers are classified based on the type of fire they are designed to combat. Knowing the fire classes is paramount to selecting the appropriate extinguisher:

  • Class A Fires: Ordinary combustibles, such as wood, paper, and textiles. These fires are the most common type and can be ignited by a heat source like a lit match or electrical spark. They burn readily, releasing heat and producing smoke and ash as byproducts.
  • Class B Fires: Flammable liquids and gases, including gasoline, oil, propane, and alcohol. These fires can be dangerous because they spread rapidly and can be reignited easily if not extinguished properly. Flammable liquids can produce vapors that travel to an ignition source and cause a flashback fire, creating a sudden and dangerous burst of flames.
  • Class C Fires: Electrical fires involving energized equipment. Electrical wiring, overloaded circuits, and faulty appliances can all spark electrical fires. These fires pose a significant danger because they can also cause electrical shock. It’s important to remember never to use water on an electrical fire, as this can conduct electricity and worsen the situation. There you have your answer on which extinguisher is used for electrical fires.
  • Class D Fires: Combustible metals, like magnesium, lithium, potassium, and sodium. These fires can be particularly challenging to extinguish because they burn at very high temperatures, sometimes exceeding 1,500 degrees Fahrenheit (816 degrees Celsius). They can also react violently with water, making it an unsuitable extinguishing agent. Special fire extinguishers containing dry powder are designed to smother these fires and prevent the spread of flames.
  • Class K Fires: Kitchen fires fueled by cooking oils and fats. If you ever wondered how to extinguish a grease fire, this is the answer you’ve been looking for. These fires present unique challenges because water can spread burning grease and oil, potentially causing the fire to worsen. Wet chemical fire extinguishers are designed to saponify (convert to soap) the burning fats, extinguishing the fire and preventing re-ignition. Kitchen extinguishers are typically rated Class K only, but some may also have a Class B rating for use on small spills of flammable liquids.

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Multi-Purpose Extinguishers: Broadening Your Fire Defense

While some fire extinguishers are designed for specific fire classes, others offer broader protection, giving you more flexibility in extinguisher selection. Here’s a breakdown of some common multi-purpose extinguishers:

  • ABC Extinguishers: These versatile extinguishers tackle Class A (ordinary combustibles), Class B (flammable liquids and gases), and Class C (electrical fires). Ideal for environments with mixed fire risks, ABC extinguishers provide a one-stop solution for common fire hazards. Homes, offices, and retail spaces can benefit from having an ABC extinguisher readily available. They are the most common type of fire extinguisher found in residential and light commercial settings.
  • BC Extinguishers:  These extinguishers cover Class B (flammable liquids and gases) and Class C (electrical fires). They are a good choice for workshops, garages, and areas where flammable liquids are used or stored, such as automotive repair shops, marinas, and manufacturing facilities.
  • AC Extinguishers: Effective against Class A (ordinary combustibles) and Class C (electrical fires), AC extinguishers are suitable for office environments and data centers where electrical equipment is a primary concern, but there is minimal risk of flammable liquids.  They are not recommended for use on Class B fires.

Demystifying the Numbers:

The numbers on a fire extinguisher label typically come in two parts, separated by a colon (“:”). Let’s explore what each part signifies:

  • Number(s) before the colon (e.g., 2A, 10B): These numbers represent the extinguisher’s effectiveness against specific fire classes. They don’t indicate a physical quantity of extinguishing agent, but rather a rating system based on how well the extinguisher can extinguish a standardized test fire.
    • Class A Fires: For Class A fires, each number roughly translates to 1 ¼ gallons of water in extinguishing power.  For instance, a 2A extinguisher is roughly as effective as 2 ½ gallons of water on a Class A fire.  A higher number signifies greater effectiveness in tackling Class A fires. Imagine a wastebasket overflowing with paper and cardboard – a 2A extinguisher would be sufficient to extinguish a fire of that size. But if you’re facing a blazing armchair, a 4A or higher rating would be more appropriate.
    • Class B Fires: Here, the number indicates the approximate square footage of burning flammable liquid the extinguisher can extinguish.  A 10B extinguisher can effectively control a fire involving flammable liquids spread over roughly 10 square feet, while a 20B extinguisher can handle a larger area, around 20 square feet. Picture a small paint spill fire – a 10B extinguisher could potentially handle it. But for a larger gasoline spill, a 20B or higher rating would be recommended.
  • Letter(s) after the colon (e.g., :B, :BC): These letters represent the fire class(es) the extinguisher is designed for.
    • A: Effective against Class A fires (ordinary combustibles).
    • B: Effective against Class B fires (flammable liquids and gases).
    • C: Effective against Class C fires (electrical fires).

Putting it All Together:

Here are some examples to illustrate how the numbers and letters work together:

  • 2A:10B:C: This extinguisher is a versatile choice, tackling Class A fires (ordinary combustibles) as effectively as 2 ½ gallons of water, Class B fires (flammable liquids) burning over an area of about 10 square feet, and Class C fires (electrical hazards). It’s a great all-around extinguisher for homes and offices where you might encounter ordinary combustibles, flammable liquids in small quantities, and potential electrical hazards.
  • 40A: This extinguisher excels at combating Class A fires (ordinary combustibles), offering extinguishing power equivalent to roughly 50 gallons of water. It’s ideal for environments with a high risk of fires involving ordinary combustibles, such as wood workshops or areas with a lot of paper and fabric. However, it’s not rated for Class B or C fires, so it wouldn’t be suitable for flammable liquids or electrical hazards.
  • CO2: This simple label indicates a Carbon Dioxide extinguisher, effective against Class B (flammable liquids and gases) and Class C (electrical fires) due to its oxygen-displacing properties. However, it has no rating for Class A fires (ordinary combustibles). CO2 extinguishers are a good choice for offices with electrical equipment or server rooms, but not for areas with a high risk of common fires involving paper, wood, or textiles.

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At Indiana Alarm, We’re #InThisTogether. We repair, service and inspect fire extinguishers. Contact us today for a free quote

Unveiling the Arsenal: A Closer Look at Fire Extinguisher Types

Now that you’re familiar with fire classifications, let’s explore the different fire extinguisher types and their unique properties:

  1. Water-Based Fire Extinguishers (Class A):
    • Mechanism: Water extinguishers cool and smother fires involving ordinary combustibles. The discharged water leaves minimal residue.
    • Applications: Homes, offices, and environments with ordinary combustibles are prime candidates for water-based extinguishers.
    • Limitations: Ineffective against flammable liquids and electrical fires. Water can also damage electrical equipment.
  2. Foam Fire Extinguishers (Class A & B):
    • Mechanism: Foam extinguishers blanket the fire, creating a barrier that suffocates the flames and prevents re-ignition. They are particularly effective against flammable liquid fires by separating the fuel from oxygen.
    • Applications: Laboratories, garages, and industrial settings that handle flammable liquids can benefit from foam extinguishers.
    • Limitations: Unsuitable for electrical fires.
  3. Dry Chemical Fire Extinguishers (Class A, B, C):
    • Mechanism: Dry chemical extinguishers release a fine powder that disrupts the chemical reaction of the fire, effectively extinguishing Class A (ordinary combustibles), Class B (flammable liquids and gases), and Class C (electrical fires).
    • Applications: Due to their versatility, dry chemical extinguishers are ideal for environments with mixed fire hazards, such as workshops, garages, and industrial settings.
    • Considerations: The discharged powder can leave a messy residue that might obstruct vision in confined spaces.
  4. CO2 Fire Extinguishers (Class B & C):
    • Mechanism: CO2 extinguishers displace oxygen in the fire zone, suffocating the flames. They leave no residue, making them perfect for use on sensitive electronic equipment.
    • Applications: CO2 extinguishers are well-suited for offices, server rooms, and areas with valuable electrical equipment.
    • Precautions: CO2 extinguishers are ineffective against Class A fires involving ordinary combustibles. Use with caution in small spaces, as CO2 displacement can cause oxygen deprivation.
  5. Wet Chemical Fire Extinguishers (Class K):
    • Mechanism: Wet chemical extinguishers are specifically designed for kitchen environments. They create a cooling effect and form a barrier on the surface of burning cooking oils and fats, preventing re-ignition.
    • Applications: Wet chemical extinguishers excel in commercial kitchens where fires involving cooking oils and fats are a significant risk.
  6. Clean Agent Fire Extinguishers (Class B & C):
    • Mechanism: Clean agent extinguishers utilize gases like halotron to interrupt the chemical reaction of the fire without leaving residue. This makes them ideal for protecting sensitive materials and electronics.
    • Applications: Clean agent extinguishers are well-suited for data centers, laboratories, and offices where valuable equipment and documents are present. Some clean agent extinguishers are also rated for Class A fires, depending on the specific agent and extinguisher size.
  7. Water Mist Fire Extinguishers (Class A & C):
    • Mechanism: Water mist extinguishers employ microscopic water droplets to cool the fire and displace oxygen. They are safe for use on electrical fires due to the minimal water used.
    • Applications: Originally designed for MRI rooms due to their safety around delicate equipment, water mist extinguishers are now finding use in various environments.

What’s inside a fire extinguisher?


The fire extinguisher’s internal components depend on the type of extinguisher, but here’s a breakdown of the common elements and how they work together:

  1. Pressurized Shell:
  • This is the sturdy metal container that holds all the fire-fighting ingredients under high pressure. It’s designed to withstand the internal pressure and the rigors of use.
  1. Extinguishing Agent:
  • This is the star of the show! It’s the material that’s expelled to extinguish the fire. The type of agent depends on the fire class the extinguisher is designed for. Here are some common ones:
    • Water: Used in Class A extinguishers for ordinary combustibles (wood, paper). It cools and smothers the fire.
    • Foam: Effective in Class A and B fires (flammable liquids). It forms a blanket that suffocates the flames and prevents reignition.
    • Dry Chemical Powder: A versatile option for Class A, B, and C fires (electrical). This powder disrupts the chemical reaction of the fire, extinguishing it.
    • CO2 (Carbon Dioxide): Used in Class B and C fires. CO2 displaces oxygen, suffocating the flames. It leaves no residue, making it ideal for electronics.
    • Wet Chemical Agent: Designed specifically for Class K fires (kitchen grease). It saponifies (turns to soap) the burning fats, extinguishing the fire.
    • Clean Agent: Utilizes gases like halotron to interrupt the chemical reaction in Class B and C fires. It leaves no residue, protecting sensitive equipment.
  1. Propellant Gas:
  • This gas (often nitrogen) keeps the extinguishing agent under pressure. When you squeeze the handle, this gas forces the agent out of the extinguisher through a nozzle.
  1. Discharge Mechanism:
  • This is the trigger or handle you squeeze to release the extinguishing agent. It activates a valve that allows the pressurized gas to propel the agent out of the extinguisher.
  1. Pressure Gauge (Optional):
  • This gauge indicates the internal pressure of the extinguisher. It’s crucial to ensure the extinguisher is properly charged and ready for use.

Remember: Different fire extinguisher types may have variations in these components. Always refer to the owner’s manual for specific details on your extinguisher.

How does a fire extinguisher work?

Fire extinguishers are like portable firefighters, each containing a specific agent designed to disrupt the fire triangle – the three elements (heat, oxygen, and fuel) needed for a fire to exist. Here’s a breakdown of how a fire extinguisher works, considering the common types:

  1. The Trigger and Release:

Imagine a fire erupting! In that critical moment, you grab the fire extinguisher and firmly squeeze the discharge lever (often a handle or trigger on top). This action activates a valve inside the extinguisher, allowing the pressurized gas to surge into action.

  1. Pressurized for Action:

Most fire extinguishers contain a pressurized gas, typically nitrogen. This gas sits above the fire extinguishing agent in the extinguisher’s sturdy metal shell. Squeezing the lever releases the pressurized gas, transforming it from a stored source of potential energy into a forceful propellant.

  1. Agent on the Move:

The pressurized gas acts like a firefighter’s hose, pushing down on the extinguishing agent. This creates a forceful stream or cloud of the agent that gets expelled through the nozzle at the end of the extinguisher. The nozzle is designed to focus the agent in a specific direction, ensuring accurate targeting of the flames.

  1. Targeting the Flames:

You aim the extinguisher nozzle at the base of the fire, where the fuel is strongest. Discharging the agent disrupts the fire triangle in one of two ways, depending on the extinguisher type:

  • Cooling:  Water and water mist extinguishers extinguish flames by absorbing heat. The water cools the fuel and surrounding area, preventing the fire from reaching the critical ignition temperature. Water mist extinguishers work similarly but use a much finer water spray to absorb heat and suppress the fire.
  • Smothering: Foam, dry chemical powder, and CO2 extinguishers extinguish flames by displacing oxygen. They create a barrier between the fuel and oxygen, essentially suffocating the fire. Wet chemical extinguishers for kitchen fires also have a smothering effect while saponifying (turning to soap) the burning fats.
  1. Putting it Out:

As you discharge the agent and keep aiming at the base of the fire, the flames will sputter and eventually die out. Remember, it’s crucial to continue discharging the extinguisher until the fire is completely extinguished to prevent re-ignition.

Here’s a quick tip:  Remember the acronym PASS to remember the fire extinguisher operation sequence: Pull the pin, Aim at the base of the fire, Squeeze the lever, and Sweep the nozzle across the fire.

Important Considerations:

  • Different fire extinguisher types use different agents, so their effectiveness varies depending on the fire class (ordinary combustibles, flammable liquids, electrical fires, etc.).  Always choose the right extinguisher for the type of fire you might encounter.
  • Fire extinguishers are designed for small fires. If the fire is large or spreading rapidly, evacuate immediately and call the fire department.
  • Regularly inspect and maintain your fire extinguisher to ensure it’s properly charged and ready for use in an emergency.

Do Fire Extinguishers Expire?

Fire extinguishers might not have a traditional “expiration date” like a carton of milk, but they do have a limited lifespan and require regular maintenance to function properly. Here’s a breakdown of key points to keep your fire extinguisher in top shape:

Limited Lifespan, Not Expiration:

  • Unlike food or medicine, fire extinguishers don’t have a set “use by” date. However, the pressure within the extinguisher and the integrity of the internal components can degrade over time, affecting their effectiveness.
  • Most manufacturers estimate a lifespan of 10-12 years for disposable extinguishers and 5-15 years for rechargeable ones, depending on the type and usage. Factors like extreme temperatures, exposure to harsh elements, or even just jostling around can accelerate wear and tear. Regular maintenance helps mitigate these risks and ensures your extinguisher is ready to perform when you need it most.

mc ing lue fire inspection

Inspection is Key:

  • Regular inspection is crucial to ensure your fire extinguisher is ready when you need it most. Here’s a basic inspection routine you can perform monthly:
    1. Visual Inspection: Look for any physical damage to the extinguisher shell, pressure gauge, hose, and nozzle. Check for signs of rust, corrosion, leaks, or dents.
    2. Tamper Seal: Ensure the tamper seal is intact, indicating nobody has tampered with the extinguisher.
    3. Pressure Gauge: The pressure gauge should be in the green zone, indicating the extinguisher agent is properly charged. Refer to the owner’s manual for the specific pressure range for your extinguisher.

Professional Maintenance Matters:

  • While monthly inspections are essential, professional maintenance is recommended every 6-12 years (depending on the extinguisher type and manufacturer’s recommendations). A qualified technician will perform a more comprehensive inspection, including:
    • Discharging a small amount of agent to check internal pressure and functionality of the pressurized propellant gas.
    • Cleaning and lubricating internal components to ensure smooth operation and prevent corrosion.
    • Replacing any worn or defective parts, such as hoses, seals, or nozzles, to maintain optimal performance.
    • Refilling the extinguisher with fresh agent and propellant gas (for rechargeable extinguishers) to ensure they have the power to extinguish a fire.

Recharging vs Replacing:

  • Disposable extinguishers:  These extinguishers, typically used for Class A fires (ordinary combustibles), are designed for single use. Once discharged, even partially, they cannot be refilled and need to be replaced with a new extinguisher.
  • Rechargeable extinguishers: These extinguishers, designed for multiple fire classes (like Class A, B, and C), can be refilled and serviced by a qualified technician after use or reaching their service interval.  Refilling a rechargeable extinguisher is generally more cost-effective and environmentally friendly compared to replacing a disposable one.

Responsible Disposal:

  • When a disposable extinguisher reaches its lifespan or a rechargeable one is no longer serviceable, proper disposal is crucial.  Fire extinguisher disposal regulations can vary by location. Here are some steps to take:

Contact your local fire department or waste management agency.

  1. They can advise on proper disposal procedures  in your area. Some fire departments or extinguisher service companies may even offer collection programs for old extinguishers.
  2. Never attempt to puncture or incinerate a fire extinguisher. This can be dangerous and release harmful chemicals. Even if an extinguisher seems inactive, it may still contain residual pressure or hazardous materials that require proper handling.

By understanding these points and following a regular inspection and maintenance routine, you can ensure your fire extinguisher is a reliable ally in your fight against fire emergencies. Remember, a functional fire extinguisher can make a critical difference in containing a small fire before it grows out of control.


By understanding the fire classifications and the meaning behind the numbers on the extinguisher label, you can make an informed decision when selecting the right extinguisher for your needs. Always choose an extinguisher with a rating for the type of fire most likely to occur in your environment.

At Indiana Alarm, We’re #InThisTogether. We repair, service and inspect fire extinguishers. Contact us today for a free quote

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