The Power of a Dry Chemical Fire Extinguisher [Expert Reviews & Buyer’s Guide]

Fires break out with no warning. As such, you need to be ready with a working fire extinguisher. A dry chemical fire extinguisher is the most common for outdoor spaces and select indoor use cases. 

Fires start where there is fuel, oxygen, and heat. Therefore, firefighting equipment needs to remove any of these three factors to fight a fire. A dry chemical powder extinguisher covers the fuel source with an inert solid to extinguish it. The powder works the same way sand or dirt fights a fire. Read on to learn more. 

What is a Dry Chemical Fire Extinguisher? 

A dry chemical fire extinguisher, or a multi-purpose dry chemical or ABC extinguisher, is standard for homes, workshops, and some office buildings. The extinguisher uses dry chemicals such as mono ammonium phosphate, potassium bicarbonate, and sodium bicarbonate to coat the fuel source and put out a fire. You can use it to put out class A, B, and C fires. Depending on your extinguisher type, you can use them for class E and F fires. 

Here are common use cases:

• Class A fires which involve solids such as paper, textiles, and wood 
• Class B fires that involve flammable solids such as paint, kerosene, petrol, diesel, and turpentine 
• Class C fires, which involve combustible gases such as methane and butane.
• Electrical fires for appliances rated 1000v or lower

Besides the standard extinguisher, you can go for a specialist dry chemical fire extinguisher that extinguishes metal-related fires. For instance, L2 extinguishers are ideal for fires that involve lithium. Another option is the M28 specialist powder extinguisher, which smothers all metal-related fires except those that involve lithium. 

Although they are multi-purpose extinguishers, you should not use them to fight class F fires. These fires involve cooking oil fires, such as chip pan fires. Again, the extinguishers are not effective when used in enclosed spaces. The dry powder can create a cloud of fog that limits visibility. Even worse, it is not safe to inhale the chemical powders. You should also not use extinguishers to put out fires on electrical equipment and appliances rated at more than 1000v. Avoid fighting metal-related fires unless you have a specialist dry powder fire extinguisher. 

ABC fire extinguishers feature a blue-colored label written POWDER. Some may have an ID sign that reads POWDER EXTINGUISHER. This way, you can identify them quickly. 

How Does a Dry Chemical Fire Extinguisher Work? 

When a fire extinguisher is unavailable, people use a blanket or throw sand and dirt on the fire. You can also pour salt or baking soda to blanket the fuel source to smother the fire. A dry chemical fire extinguisher works the same way with blankets, sand, dirt, and salt – it covers the fuel source to extinguish a fire. 

These chemical extinguishers can eliminate the most common fires in the kitchen and workshop. It fights fires from flammable solids, liquids, and gases. The working mode uses an inert solid to coat the fuel and put out the fire. Inside the extinguisher cylinder is a fine powder of sodium bicarbonate (baking soda) and potassium bicarbonate, which have the same properties as baking soda or mono ammonium phosphate. The latter is more popular thanks to its effectiveness. 

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Pros and Cons of Using a Dry Chemical Fire Extinguisher 

Advantages of a Dry Chemical Fire Extinguisher

• Fast Action: ABC extinguishers extinguish a fire within seconds when correctly aimed at the fuel source at the appropriate application rate. 
• Use on Live Electrical Equipment – Although the powder is ineffective on equipment rated above 1000v, it is safe to use on these equipment fires as it does not conduct electricity. 
• Extinguishers Running Fires – Running fuel fires spread fast; ABC extinguishers can stop them. When used with foam sprays, these extinguishers can cut the running fire’s fuel supply, preventing its spread. 
• Safe from Thermal Shock – Because the dry chemical powder does not conduct electricity, you can use it on hot metals in undercarriage assemblies without the risk of thermal shock.  
• Protect Yourself from Heat – When sprayed on a surface, the powder creates a shield that blocks off radiated heat. In a large fire, you can use the powder to create a shield around people and structures to prevent devastating fire damage. 
• Versatile Use – A dry chemical powder fire extinguisher effectively puts out class A, B, and C fires. It also puts out electrical fires on appliances rated 1000v or lower. You can also go for the specialist extinguishers that put out metal-related fires. 
• Use on Wide Temperature Range – A dry chemical fire extinguisher works efficiently between -20 and 60 degrees Celsius. 

Disadvantages 

• Reduces Visibility – When sprayed, the chemical powder creates a cloud that reduces visibility. When that happens, the operator cannot judge the exact location of the fire, which may also make it challenging for people to escape. 
• Affects Breathing – When used in an enclosed space, the operator can inhale the powder, which can irritate the breathing system. Short-term exposure is not harmful, but prolonged exposure may further damage the respiratory system. 
• Residue – After application, the powder leaves a messy residue that needs immediate cleaning. The powder is corrosive to some metals, and thanks to its fineness, it can be abrasive. As such, one needs to use it carefully to avoid causing more damage than the fire would have. When used in the kitchen, the powder can contaminate food. In the office, the chemical powder will make electrical components such as keyboards unusable. When used outdoors on a windy day, the fine powder can spread over a wide area, increasing the risk of contamination. 
• Risk of Re-Ignition – The dry chemical powder works as long as it stays above the fuel. The powder’s fine particles can blow away on a windy day, causing the fire to re-ignite.  
• Risk of Packing Down – The powder can pack down after a long time in the cylinder. This is common for a dry chemical fire extinguisher in a motor vehicle or any other area that experiences a lot of vibrations. The extinguisher fails to work when the powder packs down. You must assess the extinguisher’s functionality to avoid failure during emergencies. 
• Breaks Down a Foam Blanket – When applied, the chemical powder can break down a foam blanket. 

Thanks to the advantages and disadvantages above, a dry chemical fire extinguisher is only effective in industrial and residential settings where there is no risk of contamination. At home, it works best in a garage or workshop where you face the risk of fuel and chemical fires. 

It works best on a calm day. It could be more effective in fighting class D and F fires. 

Different Types of Dry Chemical Fire Extinguishers 

A dry chemical fire extinguisher can be classified based on the fire class it fights or the chemical powder in it. Based on function, there are two types of fire extinguishers:

Standard Dry Chemical Powder Extinguisher 

These extinguishers are versatile to put out class A, B, and C fires. Also known as ABC fire extinguishers, these units can fight:

• Class A fires 
• Class B fires
• Class C fires 
• Electrical fires for equipment rated 1000v or lower 

Specialist Dry Chemical Powder Extinguisher 

These are ideal for lithium and all flammable metal fires – the L2 and M28 extinguishers. 

Based on the chemical powder used in the cylinder, there are four types of powder chemical extinguishers:

• Monoammonium Phosphate This substance is the most common for powder extinguishers. They are multi-purpose chemical extinguishers that can put out class A, B, and C fires. The powder is a mixture of ammonium sulfate and mono-ammonium phosphate, the latter being the extinguishing component. Depending on industry standards, the combination can be 60-40% or 40-60%. 
• Sodium Bicarbonate – Baking soda is a common extinguishing chemical and is even helpful when a fire extinguisher is not available. It worked perfectly on class B and C fires and was the first chemical used in extinguishers. In an extinguisher, baking soda heats up and releases a cloud of carbon dioxide, depriving the fire of oxygen and smothering it. However, you cannot use these extinguishers on class A fires as they are ineffective in reducing fire heat, meaning they do not prevent reflashing of burning materials. 
• Potassium Bicarbonate (Purple-K) – Purple-K can put out class B and C fires. The substance is twice as effective as baking soda. It works well in the oil and gas industry as it is the only certified chemical agent used in Aircraft Rescue and Fire Fighting (ARFF). 
• Potassium Bicarbonate and Urea Complex – Also known as Monnex or Powerex, the complex chemical can break into tiny particles when sprayed on the surface of a fire. It spreads over a large area to suppress a running fire. 

Besides having the right extinguisher, ensure you have the right size. For instance, you can use the 2kg model, which will suit the needs of most homes while being light enough and easy to operate. Larger models are ideal for putting out large fires in workshops and garage forecourts. However, these are heavier, and operations can be relatively challenging. 

Comparing Dry Chemical Extinguishers with Other Types 

The dry chemical fire extinguisher is not practical for all classes of fire. As such, you might need to buy other fire extinguishers to meet all your firefighting needs. When shopping, you need to consider the materials in the room or area you need to protect. For instance, a place with flammable solids such as paper, wood, and clothes needs protection from class-A fires. 

All portable fire extinguishers are red, with a small colored band showing their type. For instance, a dry chemical fire extinguisher will have a blue bar that reads POWDER. A red band is for water extinguishers, cream for foam units, yellow for extinguishers used for wet chemicals, white and red for water mist, black for CO2, and green for clean agent extinguishers. 

Here are the six types of fire extinguishers and their uses:

Water Fire Extinguishers 

These red-label extinguishers are only ideal for class-A fires. You can use them for fires involving coal, paper, wood, rubber, coal, textiles, soft plastics, and soft furnishings. They contain water in their cylinder and work by spraying it from a nozzle at high pressure. When used well, the extinguishers can cover a vast area. They are more affordable compared to dry chemical fire extinguishers. Some units may contain an additive that makes the fire extinguishers more effective while reducing the overall size of the extinguishers. However, these options are more expensive. 

Since the extinguishers only contain water, they are easy to maintain and have a lower risk of failure. They suppress a fire by reducing the surface heat when materials soak in water. You can use these options in shops, retail premises, schools, hotels, residential premises, and warehouses. Although they leave a little mess behind, they are easier to clean than dry chemical powder. 

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Water Mist Extinguishers 

Water mist extinguishers are relatively new in the market. They are more compact and robust and work by releasing a fine mist of demineralized water particles. You can use them on class A, B, and C fires, like the dry chemical powder extinguisher, but they also suppress class F fires. They are highly versatile, so you do not need several extinguishers in your home. Some units effectively put out electrical fires for appliances rated 1000v or lower. 

Water mist extinguishers suppress a fire by cooling the surface and depriving the fire of oxygen. Unlike dry chemical extinguishers, these extinguishers leave no residue and do not corrode surfaces. They contain no chemicals, so you can recycle them. The extinguishers are more expensive than water extinguishers. 

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Foam Fire Extinguishers 

The cream-labeled fire extinguishers suppress fires involving flammable solids and liquids (class A and B fires). You can use them on electrical fires if you spray them from a meter away. After use, you will need to clean up the residue. Again, the units are more expensive than water extinguishers. 

Foam fire extinguishers are ideal for use in homes, offices, workshops, garage forecourts, and many other areas. They extinguish fires involving papers, textiles, turpentine, petrol, paint, and other solids and liquids. 

Water Spray Fire Extinguishers 

These extinguishers come in three- and six-liter cylinders. They effectively put out fires involving flammable solids such as wood, textiles, coal, plastics, and paper. Never use them on fat and oil-related fires or electrical equipment. You need to aim the nozzle at the base of the flames, spray, and move across the fire until it successfully suppresses it.

Instead of a jet nozzle, the extinguishers have a spray nozzle that allows the unit to produce a fine spray from the high pressure inside the cylinder. When used correctly, the extinguisher can suppress fire over a large area and extract heat faster. Manufacturers sometimes use surfactants to ensure the water penetrates further into the burning material. 

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CO2 Fire Extinguishers 

CO2 fire extinguishers contain pressurized carbon dioxide, depriving a fire of oxygen to smother it. The extinguishers leave no residue after use and are ideal for class B and electrical fires. As such, you can use them in offices, garage forecourts, and workshops where petroleum and flammable liquids are common. The CO2 does not cause damage to equipment and does not contaminate food or the surrounding area. 

The main disadvantage of CO2 extinguishers is that they get cold during use. The operator’s hands will freeze if the cylinder lacks a double lining and a frost-free swivel. Please do not use them enclosed, as they can cause asphyxiation. Again, please do not use them on deep-fat fryers, as the jets from the cylinder can cause the fat to fly off the fryers. 

CO2 extinguishers, like dry chemical powder extinguishers, do not offer the best post-fire security, as a fire can re-ignite when the CO2 dissipates into the atmosphere. The extinguishers are always relatively expensive. 

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Wet Chemical Fire Extinguishers 

These extinguishers have a yellow label. They are ideal for fighting class F fires, which involve fats and oils. You can, therefore, use them in the kitchen and on deep-fat fryers. Besides class F, you can use them on class A and B fires. 

Inside their cylinders are pressurized alkali salts dissolved in water. During operation, the extinguisher releases a fine mist that reduces the heat of the flames without causing a splash. You will pay more for the extinguishers compared to water and water mist extinguishers. 

All the above fire extinguishers are easy to use. However, a fire extinguisher is only effective when used by trained hands. To activate the fire extinguisher, the fire alarm must first go off, and an evacuation route must be decided.

  If using the fire extinguisher doesn’t feel like a safe option, or the fire keeps spreading even after using the extinguisher, exit the building. 

Use the PASS method of extinguishing a fire with any of the above extinguishers. Pull the extinguisher pin. Aim the extinguisher nozzle at the base of the fire. Squeeze the handle. Sweep from side to side until the fire is out. 

Frequently Asked Questions (FAQs) 

Can I use a powder fire extinguisher on an electrical fire?

Yes. This equipment can suppress electrical fires in appliances rated 1000v or less. However, some electrical components, such as keyboards, will be unusable after use. The chemical powder does not conduct electricity, and you can use it to gain access where an electric fire blocks your access to power outlets. 

Are dry chemical extinguishers safe to use indoors?

A dry chemical fire extinguisher is not safe for use indoors. For starters, the discharge of the chemical powder reduces visibility, making it challenging for the operator to determine the effectiveness of the extinguishing process. The cloud of powder may also make it difficult for people to evacuate a building. In an enclosed space, operators can inhale the powder, irritating the respiratory system. 

How do I clean up after using a dry chemical fire extinguisher?

The dry powder is easy to vacuum after suppressing a fire. You can also sweep it off surfaces and dispose of it appropriately. If the residue adheres to surfaces or hardens, clean it with isopropyl alcohol diluted with warm water. The alcohol breaks down the hardened residue, making it easier to remove. If the extinguisher uses sodium or potassium bicarbonate, you can use hot water and vinegar to neutralize the residue and then wipe it off with a wet cloth. 

Can dry chemical extinguishers be used on flammable liquids?

Yes. The extinguishers are effective on class B fires that involve flammable liquids such as gasoline, turpentine, paraffin, and many others. They cut off the fuel supply by creating a coat around it to smother the fire. 

What should I do if my dry chemical extinguisher is not working correctly?

The main problem a dry chemical powder extinguisher might face is packing down. This happens when the chemical powder compacts to the bottom of the cylinder, especially after it is exposed to vibrations. You can prevent packing by placing the extinguisher where there are no vibrations. Even better, invert the extinguisher occasionally and pat its bottom. After six years, you need a professional to maintain and repair the extinguisher. 

Final Word

You need a fire extinguisher to help you suppress fires caused by different fuels. A dry chemical fire extinguisher can put out fires in three classes, as well as electrical fires. If you have a specialist extinguisher, you will put out metal fires. In a place of business where different fuels can cause a fire, you might need to get another type of fire extinguisher. 

Getting the right size and weight of a dry powder extinguisher is as essential as knowing how to use it. The extinguisher should meet the set fire safety regulations for your industry. You need to go through training to use a fire extinguisher effectively; this text does not count as training. After learning how to use the equipment, contract a professional once in a while to inspect, maintain, and repair the extinguisher to ensure it is ready to suppress a fire at all times.