Fire extinguishers are essential safety devices that can help prevent the spread of fire and protect people and property from harm. However, not all fire extinguishers are the same. Different types of fire extinguishers are designed for different classes of fire, and using the wrong one can be ineffective or even dangerous.
In this article, we will compare two common types of fire extinguishers: CO2 and foam. We will explain how they work, what they are suitable for, and what are their pros and cons. We will also provide some tips on how to choose the right fire extinguisher for your needs.
Key Takeaways
| CO2 Fire Extinguisher | Foam Fire Extinguisher |
|---|---|
| Contains pure carbon dioxide gas | Contains water mixed with foaming agent |
| Works by suffocating the fire and displacing oxygen | Works by cooling the fire and forming a barrier over the fuel |
| Suitable for Class B (flammable liquids) and electrical fires | Suitable for Class A (combustible materials) and Class B fires |
| Leaves no residue and does not damage electrical equipment | Leaves a wet residue that may need to be cleaned up |
| Not effective on Class A fires and may cause frostbite if handled improperly | Not recommended for electrical fires and may freeze in cold temperatures |
How Does a CO2 Fire Extinguisher Work?
A CO2 fire extinguisher contains pure carbon dioxide gas under high pressure. When the extinguisher is activated, the gas is released through a horn or a hose at a very low temperature. The CO2 works by suffocating the fire and displacing the oxygen that it needs to burn. This type of extinguisher is suitable for Class B fires, which involve flammable liquids such as petrol, oil, or paint. It is also recommended for electrical fires, as it does not conduct electricity or damage electrical equipment⁴.
Advantages of CO2 Fire Extinguishers
- They are a “clean” extinguisher that leaves no residue after use. This can be a significant factor where protection is needed for delicate and costly electronic equipment³. Other typical applications are food preparation areas, laboratories, and printing or duplicating areas.
- They are easy to use and operate. They have a simple mechanism that requires only squeezing the lever to release the gas.
- They are relatively lightweight and compact compared to other types of fire extinguishers.
Disadvantages of CO2 Fire Extinguishers
- They are not effective on Class A fires, which involve ordinary combustible materials such as wood, paper, or cloth⁴. The CO2 gas can blow away the burning materials and spread the fire instead of extinguishing it.
- They can cause frostbite or burns if handled improperly. The gas is very cold and can freeze the skin or eyes if it comes in contact with them. The horn or hose should not be touched during or after use.
- They have a limited range and discharge time. The gas disperses quickly in the air and does not last long. The user has to get close to the fire and aim carefully at the base of the flames.
How Does a Foam Fire Extinguisher Work?
A foam fire extinguisher contains water mixed with a foaming agent that creates a layer of foam when sprayed on a fire. The foam works by cooling the fire and forming a barrier over the fuel, preventing it from vaporizing and reigniting. This type of extinguisher is suitable for Class A fires, which involve combustible materials such as wood, paper, or cloth. It can also be used on Class B fires, which involve flammable liquids such as petrol, oil, or paint.
Advantages of Foam Fire Extinguishers
- They are versatile and can be used on both Class A and Class B fires. They are ideal for premises with multiple fire risks, such as offices, warehouses, factories, garages, hotels, etc.
- They are more effective than water extinguishers on Class A fires, as they have a longer lasting cooling effect and reduce the risk of re-ignition.
- They have a longer range and discharge time than CO2 extinguishers. They can reach up to 6 meters and last up to 60 seconds.
Disadvantages of Foam Fire Extinguishers
- They leave a wet residue that may need to be cleaned up after use. The residue may also cause damage to some materials or equipment, such as carpets, fabrics, or electronics.
- They are not recommended for electrical fires, as they may conduct electricity and cause shocks or short circuits⁶. They should only be used on electrical equipment that is unplugged or isolated from the power source.
- They may freeze in cold temperatures and become unusable. They should be stored in a frost-free location and checked regularly for signs of freezing.
How to Choose the Right Fire Extinguisher for Your Needs
The choice of a fire extinguisher depends on several factors, such as the type and size of fire, the location and environment, and the availability and accessibility of the extinguisher. Here are some general tips to help you choose the right fire extinguisher for your needs:
- Identify the class of fire that you are most likely to encounter in your premises. You can use the following table to help you:
| Class of Fire | Description | Examples |
|---|---|---|
| A | Fires in ordinary combustible materials, such as wood, cloth, paper, rubber, and many plastics | Furniture, books, curtains, trash bins |
| B | Fires in flammable liquids, combustible liquids, petroleum greases, tars, oils, oil-based paints, solvents, lacquers, alcohols, and flammable gases | Petrol, diesel, paint, thinner, propane |
| C | Fires that involve energized electrical equipment | Computers, printers, wires, appliances |
| D | Fires in combustible metals, such as magnesium, titanium, zirconium, sodium, lithium, and potassium | Metal shavings, powders, flakes |
| K | Fires in cooking appliances that involve combustible cooking media (vegetable or animal oils and fats) | Deep fryers, ovens, stoves |
- Choose a fire extinguisher that is suitable for the class of fire that you are most likely to encounter. You can use the following table to help you:
| Type of Fire Extinguisher | Suitable for Class | Not Suitable for Class |
|---|---|---|
| Water | A | B,C,D,K |
| Foam | A,B | C,D,K |
| CO2 | B,C | A,D,K |
| Dry Powder | A,B,C,D | K |
| Wet Chemical | K | A,B,C,D |
- Consider the size and weight of the fire extinguisher. You should choose a fire extinguisher that is easy to handle and carry by anyone who may need to use it. The size and weight of the fire extinguisher also affect its capacity and performance. Generally speaking, the larger the fire extinguisher, the longer it lasts and the farther it reaches. However, larger fire extinguishers may also be more expensive and require more space and maintenance. You should balance these factors according to your budget and needs.
- Consider the location and environment of the fire extinguisher. You should choose a fire extinguisher that is suitable for the location and environment where it will be stored and used. For example, you should avoid storing water or foam extinguishers in freezing temperatures or near electrical equipment. You should also avoid storing CO2 extinguishers near heat sources or in confined spaces. You should place the fire extinguisher in a visible and accessible location that is close to the potential fire hazards but away from the fire itself.
- Follow the instructions and guidelines provided by the manufacturer and local authorities. You should always read and follow the instructions and guidelines provided by the manufacturer of the fire extinguisher. You should also comply with any local regulations or standards that apply to your premises. You should check and maintain your fire extinguishers regularly to ensure they are in good working condition. You should also train yourself and anyone who may need to use them on how to operate them safely and effectively.
Conclusion
CO2 and foam fire extinguishers are two common types of fire extinguishers that have different characteristics and applications. CO2 fire extinguishers are suitable for Class B and electrical fires. They leave no residue and do not damage electrical equipment. However, they are not effective on Class A fires and may cause frostbite if handled improperly. Foam fire extinguishers are suitable for Class A and B fires. They have a longer lasting cooling effect and prevent re-ignition. However, they leave a wet residue that may need to be cleaned up and are not recommended for electrical fires.
The choice of fire extinguisher depends on several factors, such as the type and size of fire, the location and environment, and the availability and accessibility of the extinguisher. You should identify the class of fire that you are most likely to encounter in your premises and choose a fire extinguisher that is suitable for it. You should also consider the size and weight of the fire extinguisher, as well as the location and environment where it will be stored and used. You should follow the instructions and guidelines provided by the manufacturer and local authorities. You should also check and maintain your fire extinguishers.
