Not all extinguishers work the same way. Carbon dioxide (CO2) fire extinguishers are designed for fires involving flammable liquids and electrical equipment. 

They don’t leave behind foam or powder, which makes them a great choice for places with sensitive electronics, like offices or server rooms. CO2 works by pushing out oxygen and cooling the flames, which quickly stops the fire. But they can’t be used on every fire type, so knowing when to use them is key.

This guide covers what CO2 fire extinguishers are used for, how they work, how to use them properly, and more. 

What Are Carbon Dioxide Fire Extinguishers Used For?

Carbon dioxide fire extinguishers are used for Class B and Class C fires. This means they work best on flammable liquids and electrical fires. CO2 puts out flames by taking away oxygen and cooling the material that’s burning. Since it leaves no mess or residue, it’s great for places with sensitive electronics like computers, server rooms, or control panels. You’ll also find them in workshops or areas with flammable liquids. Let’s take a look at what they’re used for below:

Class B Fires: Flammable Liquids and Gases

Class B fires involve flammable liquids or gases like gasoline, paint thinner, oil, alcohol, and propane. They can occur in homes, workplaces, or industrial settings. For instance, spilled gasoline in an attached garage or spray paint fumes near a heat source can lead to Class B fires.

Once ignited, Class B fires spread fast and produce toxic fumes. Using water to extinguish a Class B fire is a bad idea because it makes things worse. However, CO2 fire extinguishers are highly effective. They suffocate the flames by removing oxygen without causing damage or contamination.

Class C Fires: Electrical Equipment

Class C fires are caused by live electrical equipment, such as computers, generators, or overloaded outlets. They can spread quickly, especially if wiring is hidden in walls. Malfunctioning appliances, like toasters or space heaters, can also start Class C fires.

CO2 extinguishers are the go-to for Class C fires because they don’t conduct electricity and don’t leave residue. As a result, they don’t damage sensitive electronics.  

What Are Carbon Dioxide Fire Extinguishers Not Used For?

Carbon dioxide fire extinguishers are handy in certain situations, but they’re not the right choice for every type of fire. Knowing when not to use them is just as important as knowing when to grab one.

First off, CO2 extinguishers should never be used on Class A fires. These are fires involving wood, paper, cloth, or other everyday combustibles. The problem is that CO2 doesn’t cool the material enough to stop it from reigniting. A foam or water extinguisher works better here.

They’re also useless against Class D fires, which involve flammable metals like magnesium or sodium. These metals can produce their own oxygen when they burn, making CO2 ineffective. For these, you’ll need a Class D extinguisher.

Another big no-go is Class K fires, which are kitchen fires that start due to cooking oils and fats. These fires are common in restaurants, home kitchens, and food trucks. However, CO2 just won’t cut it. A wet chemical extinguisher is the safer option. Find out more about how to put out a grease fire here. 

Aside from fire classes, CO2 extinguishers can also be dangerous in the wrong setting. Using one in a confined space is risky because the gas pushes out oxygen. That might put out the fire, but it can also make it hard for people to breathe. Similarly, they’re not great in windy outdoor conditions. The gas can blow away too quickly and leave the flames untouched.

It’s also worth noting that fires involving flammable metals or self-oxidizing materials shouldn’t be tackled with CO2, since they can keep burning even without outside oxygen. On top of that, the CO2 horn gets extremely cold during use and can cause frostbite if you touch it. The sudden cold discharge can also create moisture in the air, which could damage certain environments.

How Does a CO2 Extinguisher Work?

A CO2 fire extinguisher works by attacking a fire in two key ways: it takes away the oxygen and cools down the burning material. Since fires need oxygen to keep going, the carbon dioxide gas smothers the flames by pushing the oxygen out of the way. At the same time, the gas is released at an extremely cold temperature, which helps cool the fuel and lowers the chance of the fire starting back up.

The CO2 is stored as a liquid under high pressure. When you press the handle, it shoots out through the nozzle and turns into a white, fog-like cloud that blankets the flames. This makes it especially effective for Class B fires (flammable liquids) and Class C fires (electrical equipment).

One of the biggest advantages is that CO2 leaves no residue. That’s why it’s often used around electronics, server rooms, or other valuable equipment. There’s no messy cleanup or damage to wires and circuits. Plus, because it’s a non-conductive gas, it’s safe to use around energized electrical devices.

That said, there are safety points to keep in mind. The nozzle, or horn, gets extremely cold when the CO2 is discharged and can cause frostbite if touched. Plus, using it in a small or enclosed area without proper ventilation can be risky since the gas pushes oxygen out of the air. So, always make sure the space is safe before and after use.

Carbon Dioxide Fire Extinguishers Are Designed for Which Types of Fuels?

Carbon dioxide fire extinguishers are designed to put out fires fueled by electrical equipment, flammable liquids, and flammable gases. The fuels they work on include gasoline, oil, alcohol, solvents, diesel, kerosene, propane, butane, and natural gas. They’re useful in places where fuels like these are stored or used, such as garages, workshops, or laboratories.

In particular, carbon dioxide fire extinguishers smother the flames by removing oxygen and cooling the fuel at the same time. Plus, it doesn’t leave behind messy residue, so it’s safe to use around electronics. However, it’s not suitable for solid fuels like wood, paper, or cloth, because those materials can keep burning underneath and reignite. It’s also not meant for cooking oils or fats, since the strong discharge can spread the flames.

CO2 Fire Extinguisher Alternatives

While carbon dioxide fire extinguishers help a lot, they can be expensive, heavy, and difficult to store. They might also leave a mess that’s hard to clean up. 

A fire spray is an easy-to-use, lightweight, and affordable alternative to  CO2 fire extinguishers. Prepared Hero’s fire spray is also biodegradable and non-toxic. Unlike a fire extinguisher, you can safely use it around your family and pets. 

Here’s a table summarizing the differences between Prepared Hero’s fire spray and a regular carbon dioxide fire extinguisher:

Another alternative is a fire blanket, which depletes the fire’s oxygen supply. By doing this, it puts out small fires in seconds. It also doesn’t leave a mess because it simply covers the fire.

Unlike carbon dioxide fire extinguishers, Prepared Hero’s fire blanket doesn’t expire. You can reuse it as many times as you want as long as it’s not damaged. Plus, you can use it to save someone from fire. 

Here’s a table summarizing the differences between Prepared Hero’s fire blanket and a regular CO2 fire extinguisher:

Do you want reliable, easy-to-use, and affordable tools to put out small fires before they become raging infernos? Check out Prepared Hero’s fire prevention tools here, and get up to 51% off on certain items. 

Which Fire Extinguisher Is Used for Fuel?

The fire extinguisher used for fuel like gasoline and diesel is a Class B fire extinguisher. They’re made to handle flammable liquids and gases such as propane, oil, diesel, and vapors from cleaning agents or solvents. Using water on these fires is dangerous because it can spread the liquid and make the flames worse, so a Class B extinguisher is the safe option.

You can easily spot one by checking the label. Look for a red square with the letter “B” on it. That symbol tells you it’s designed for fuel-related fires.

Class B extinguishers can work in a few different ways, depending on the type:

• Foam: This creates a blanket over the liquid, sealing in vapors and cutting off oxygen so the fire can’t keep burning.

• Powder: The dry chemical interrupts the chemical reaction that keeps the flames going while also blocking oxygen.

• Carbon dioxide (CO2): The CO2 gas displaces oxygen and cools the fire, smothering it quickly without leaving a mess behind.

• Water mist: They use deionized water, which is non-conductive and non-toxic.

Each of these agents works by cutting off oxygen, cooling the fire, or both. That’s why they’re so effective against fuels. Whether you’re dealing with a spill in a detached garage, fuel vapors in a workshop, or propane in an outdoor setting, a Class B extinguisher is what you’ll need to stay safe.

Can CO2 Extinguishers Be Used on Oil Fires?

CO2 extinguishers can be used on some oil-related fires, but not all of them. They’re effective on Class B fires, which include flammable liquids like petrol, diesel, and other fuel oils. In these cases, the carbon dioxide gas works by pushing oxygen out of the area and cooling the flames, which stops the fire from burning. They’re also safe for electrical fires since CO2 is non-conductive and leaves no residue behind.

But here’s where it gets tricky: CO2 extinguishers are not safe for cooking oil or fat fires. These are known as Class K fires. If you spray a CO2 extinguisher onto burning cooking oil, the force of the discharge can actually cause the hot oil to splash and spread the flames. 

On top of that, CO2 doesn’t create the protective soapy film needed to stop the fire from reigniting. That’s why kitchens should always have a Class K extinguisher, which is the type specifically designed for grease fires. 

It’s also important to remember that CO2 extinguishers displace oxygen. This makes them unsafe to use in small or confined spaces because they can lower oxygen levels and put people at risk of asphyxiation.

One big advantage of CO2 extinguishers is that they leave no messy residue, which makes them perfect for places like hospitals, offices, and factories where cleanup could be a problem. Just be careful with the nozzle or horn because it gets extremely cold during use and can cause frostbite if touched.

So, while CO2 extinguishers are great for fuel-based oil fires and electrical fires, they should never be used on cooking oil fires. Always match the extinguisher type to the fire hazard.

Can a CO2 Extinguisher Be Used on a Liquid Fire?

Yes, a CO2 extinguisher can be used on a liquid fire since it’s made for Class B fires, which involve flammable liquids and gases. The CO2 works by pushing out the oxygen the fire needs and cooling down the flames. This makes it effective for things like gasoline, diesel, or solvents.

That said, using CO2 on a liquid fire comes with some cautions. The gas comes out under high pressure, and if you’re not careful, it can splash the burning liquid. This can spread the flames instead of putting them out. That’s why many people prefer a dry chemical extinguisher for liquid fires, since the powder blankets the fuel and helps prevent re-ignition.

If you do use a CO2 extinguisher on a liquid fire, the right technique matters. Aim the horn at the base of the fire. Sweep the discharge in a back-and-forth motion so the gas covers all of the burning surface. And always watch out for splashing, which can make the fire worse.

Keep in mind that the fire might reignite. CO2 removes oxygen, but once the gas clears, the liquid can catch fire again if it’s still hot. That’s another reason dry chemical extinguishers are often more reliable.

What Type of Fire Extinguisher Is Needed for Hot Oils?

The type of fire extinguisher needed for hot oils is a Class K fire extinguisher. It’s specially designed to deal with grease and oil fires that you’d find in a kitchen. Using the wrong type of extinguisher can make things worse, since water or regular dry chemicals can actually spread the burning oil instead of putting it out.

Class K extinguishers work in a unique way. When the agent is sprayed, it reacts with the hot oil in a process called saponification. This reaction creates a soap-like foam that forms a blanket over the oil. The foam cuts off the oxygen supply, cools the oil, and locks in vapors, which prevents the fire from coming back. Another big advantage is that the fine mist doesn’t cause splashing, unlike pressurized agents or water. This makes them much safer to use around burning oil.

Other extinguishers just don’t work as well in these cases. Water-based extinguishers can cause the oil to explode outward, spreading the flames. Dry chemical extinguishers may stop the fire temporarily, but they don’t cool the oil enough, so reignition is likely.

You’ll find Class K extinguishers in commercial kitchens, where large quantities of cooking oils and fats are used daily. It’s also smart to have them at home, especially if you cook with a lot of oil. 

What Fire Extinguisher Should Not Be Used on Petrol?

A water extinguisher should never be used on a petrol fire. Petrol is lighter than water, so spraying water only makes the liquid float and spread, carrying the flames with it. Instead of putting the fire out, it actually makes the situation more dangerous by spreading burning fuel to a larger area.

Other extinguishers designed for different fire classes also won’t work. A Class A extinguisher, which is meant for wood, paper, and textiles, is ineffective against petrol fires. The same goes for Class K extinguishers, which are made for cooking oils and fats. Both are designed for specific fire types and won’t safely handle petrol.

The right extinguishers for petrol fires are foam, dry powder, or CO2. Foam extinguishers create a barrier that seals in vapors and cuts off oxygen. On the other hand, powder extinguishers interrupt the chemical reaction of the fire while smothering the flames. Lastly, CO2 extinguishers push away oxygen and cool the fire.

What Does ABC Stand for on a Fire Extinguisher?

The ABC on a fire extinguisher stands for Class A, Class B, and Class C fires. This means it can put out three of the most common types of fires. Having one of these around gives you a lot of coverage for everyday fire risks. Here’s what an ABC fire extinguisher is used for: 

• Class A fires: They start with solid materials like wood, paper, cloth, or certain plastics. Class A fires usually occur in homes, offices, and schools.
• Class B fires: They involve flammable liquids such as gasoline, oil, and alcohol. These are more common in garages, workshops, and factories.
• Class C fire: They’re caused by live electrical equipment like appliances, wiring, or circuit breakers. Since electricity can’t be extinguished with water, you need something safe and non-conductive.

An ABC extinguisher uses a dry chemical agent, usually monoammonium phosphate, to put out fires. It works by smothering the flames, cutting off oxygen, and breaking the fire’s chemical reaction.

The main reason ABC extinguishers are so popular is their versatility. Instead of needing different extinguishers for different fire types, one unit can handle the three most common hazards. That’s why you’ll often see them in homes, offices, schools, and even vehicles.

They’re also safe to use on electrical fires because the chemical inside doesn’t conduct electricity. This lowers the risk of shock when fighting electrical fires.

Why is a CO2 Fire Extinguisher Not Used for Class A Fire?

A CO2 fire extinguisher is not the right choice for a Class A fire, which involves materials like wood, paper, and fabric. The reason is simple: CO2 works by removing oxygen, but it doesn’t cool the burning material. That means even if the flames go out, hot embers are left behind. Once the CO2 gas dissipates and oxygen flows back in, the fire can easily reignite.

Class A fires are tricky because they often burn deep into the material. Think of glowing embers inside a log or smoldering paper stacked together. CO2 gas can’t soak in or reach those hot spots. It just covers the flames for a moment without lowering the temperature of the fuel. That’s why it’s not reliable for these types of fires.

Water or foam extinguishers are much better for Class A fires. They not only put out the flames but also cool and soak the material. Water drops the temperature below the ignition point, while foam covers and penetrates the surface, making sure the fire doesn’t spark back up.

CO2 extinguishers, on the other hand, shine in different situations. They’re designed for Class B fires (flammable liquids like petrol or solvents) and Class C fires (electrical equipment). Since CO2 is non-conductive and residue-free, it’s safe for use around electronics and flammable liquids.

What Is the Color of a CO2 Extinguisher?

A CO2 fire extinguisher is easy to spot once you know what to look for. The main thing that gives it away is the black label or black band around the body. Most extinguishers are red, and CO2 ones are no different in that sense, but the black mark sets them apart. If you see a red extinguisher with a black label, there’s a good chance it’s a CO2 type.

Some models, especially older or chrome versions, may appear silver instead of red. But the black label and the nozzle design are always consistent. Unlike the hose you see on water or foam extinguishers, a CO2 extinguisher has a hard, horn-shaped nozzle. That horn is there to release the gas safely and helps you instantly know you’re looking at CO2.

Another thing you won’t find on a CO2 extinguisher is a pressure gauge. The gas inside is stored at very high pressure, so these extinguishers don’t need a gauge to show the level. That also makes them different from foam or powder types.

Knowing these features matters because CO2 extinguishers are meant for electrical fires and flammable liquids and gases. They work well in those situations but can be dangerous in small, closed spaces since CO2 pushes out oxygen. So, the black label and the hard horn are the most reliable ways to identify one quickly and use it safely.

How to Use a CO2 Extinguisher

Using a carbon dioxide fire extinguisher might look tricky, but the PASS fire extinguisher method makes it easy. Here’s how to use a CO2 fire extinguisher properly:

1. Pull the Safety Pin

Start by pulling the safety pin on the CO2 fire extinguisher. This unlocks the handle so you can use it. Some extinguishers may have a tamper seal. If yours does, twist or break it first to remove the pin.

2. Aim At the Base of the Fire

Next, aim the extinguisher’s nozzle or hose at the base of the fire. Don’t aim it at the flames. You should target the base because that’s where the fuel is.

3. Squeeze the Handle

Firmly squeeze the handle or lever to release the CO2. Avoid squeezing too hard, too quickly, as this can waste the agent. A steady squeeze gives you more control.

4. Sweep From Side to Side

Lastly, sweep the nozzle side to side. Slowly move and make sure you cover the entire area. Keep doing this until the fire dies. Watch out for reignition.

Remember, your safety is the priority. Only use CO2 extinguishers on manageable fires. A small flame can turn into a major fire in 30 seconds, so be careful. If the fire is spreading quickly or you feel unsafe, evacuate and call for help immediately.

Where Are CO2 Extinguishers Found?

CO2 fire extinguishers are usually found where there’s a high risk of Class B and Class C fires. You’ll often see them in offices because computers, printers, and other electronic devices are everywhere. They’re also common in server rooms, where valuable and sensitive equipment needs protection.

In addition, CO2 fire extinguishers are found in laboratories because they don't contaminate experiments or damage delicate tools. The same goes for healthcare facilities, where medical equipment needs to stay clean and functional. Kitchens often have CO2 extinguishers too, especially when there are many electrical appliances that could start a structure fire.

You’ll also find them in workshops and industrial areas. These places often store or use flammable liquids like fuel, oils, or paints, making CO2 a practical option. It can quickly smother flames without causing harm to machinery or electronics.

Which Is Better: ABC or CO2 Fire Extinguisher?

The better option between ABC and CO2 fire extinguishers depends on the type of fire you’re dealing with. 

ABC fire extinguishers are multi-purpose and work on Class A, Class B, and Class C fires. They use a dry chemical that smothers flames and prevents reignition. They’re a solid choice  for homes, offices, and cars.

On the other hand, CO2 fire extinguishers work best against Class B and C fires. They displace oxygen to suffocate flames without leaving residue. This makes them perfect for putting out fires involving sensitive equipment. However, they’re ineffective against Class A fires caused by ordinary combustibles. 

In a gist, an ABC fire extinguisher is better if you want versatility. On the flip side, CO2 fire extinguishers are the better choice if you want to protect sensitive equipment.

Conclusion

CO2 fire extinguishers are non-conductive, leave no residue, and work fast by cutting off oxygen. However, they’re not suitable for Class A, D, and K fires. Knowing what to use and how to use them makes a huge difference. Stay prepared, hero!