Types of Fire Extinguishers

Key Takeaways

Type of Extinguisher	Class of Fires	Common Uses	Key Characteristics
Water	Class A	Wood, paper, textiles	Cools burning material
Foam	Class A, Class B	Flammable liquids, solid combustibles	Creates barrier to prevent re-ignition
Dry Powder	Class A, Class B, Class C, Electrical	Various settings, including flammable gases	Interrupts chemical reactions
Carbon Dioxide (CO2)	Electrical, Class B	Electrical fires, flammable liquids	Displaces oxygen, leaves no residue
Wet Chemical	Class F	Cooking oils and fats (kitchens)	Creates a soapy film to prevent re-ignition
Class D (Specialist)	Class D	Combustible metals	Smothers fire without reacting with the metals
Water Mist	Various classes, including Class F	Multiple fire types including cooking oils and fats	Reduces oxygen level with fine water spray

Understanding the different types of fire extinguishers is essential for your safety, whether at home, in the workplace, or in public spaces. 

Each type is designed to tackle specific classes of fires, and using the wrong one can be ineffective or even dangerous. 

Fire extinguishers are categorised based on the fire suppression materials they contain, each suited for combatting different types of fires. 

The common types include water, foam, dry powder, carbon dioxide (CO2), and wet chemical extinguishers. 

Water extinguishers are ideal for fires involving organic materials, such as wood and paper, while electrical fires call for the use of CO2 extinguishers due to their non-conductive properties.

Each fire extinguisher also comes with its own set of instructions and operational procedures. 

It’s crucial to have an in-depth understanding of how to use fire extinguishers correctly to ensure that you can respond effectively and safely when a fire occurs. 

By staying informed about the extinguishing agents and their appropriate application, you ensure that you’re prepared for contingencies, preserving property and, more importantly, saving lives.

Understanding Fire Classes and Extinguishing Mechanisms

When dealing with fires, recognising the correct fire class is critical. Fire classes denote the type of fire dependent on the fuel source involved. In the UK, fire extinguishers are labelled with classes to ensure you use the appropriate one.

• Class A: These are fires fuelled by solid combustibles like wood, paper, and textiles. To extinguish these, water or foam extinguishers are typically the best choice.
• Class B: Involving flammable liquids such as petrol and paint, foam, dry powder, or CO2 extinguishers are best suited here.
• Class C: Fires caused by flammable gases, like propane and butane, require dry powder extinguishers.
• Class D: Combustible metals, such as magnesium or aluminium, need specialist dry powder extinguishers.
• Class F: Fires from cooking oils and fats are best dealt with using wet chemical extinguishers.

Understanding the mechanism of extinction is essential. 

1. Cool down the burning material, as with water and foam on Class A fires.
2. Separate the fire from its oxygen supply, like CO2 extinguishers do with Class B and electrical fires.
3. Remove the chemical reaction of the fire triangle, which is the action of dry powder on Class C and D fires.
4. Create a barrier between the fuel and the flames, characteristic of wet chemical extinguishers for Class F fires.

Water Fire Extinguishers

In this section, you will learn about water fire extinguishers, which are specifically designed for tackling Class A fires. These fires involve combustible materials such as wood, paper, and textiles. 

The effectiveness of water extinguishers stems from their cooling effect, which helps to extinguish flames and prevent re-ignition.

Effective Use for Class A Fires

Water fire extinguishers are suitable for use on Class A fires. These are fires that involve solid combustibles, including:

• Wood
• Paper
• Textiles

When using a water extinguisher, aim the jet at the base of the flames and sweep back and forth. 

The water has a cooling effect that suppresses the fire by reducing its temperature below the ignition point, effectively stopping the combustion process.

Limitations and Risks

Despite their efficacy in tackling Class A fires, water extinguishers come with certain limitations and risks:

• Not suitable for electrical fires or fires involving flammable liquids and gases.
• Can cause electric shock if accidentally sprayed onto live electrical equipment.
• May spread the fire if used on cooking oil or fat fires.

Remember that your safety is paramount. 

If you are unsure about how to use a fire extinguisher or if the fire is too large, it is crucial to evacuate the area immediately and call the emergency services.

Foam Fire Extinguishers

Foam fire extinguishers are versatile units designed specifically to tackle Class A and B fires, which involve flammable liquids and solids such as paper, wood, and textiles. They are a prime choice for a variety of environments.

Application on Class A and B Fires

Foam extinguishers are highly effective on Class A fires by creating a cooling effect on burning materials such as wood, cloth, and paper. 

They also excel in combating Class B fires which involve flammable liquids like petrol and paint. 

When you deploy a foam extinguisher, it blankets the flames, effectively cutting off the oxygen supply and preventing the fire from spreading.

Foam’s Fire Suppressing Properties

The strength of foam extinguishers lies in their dual impact: they not only cool the fire with their water content, but they also seal the surface with foam, preventing re-ignition. 

It’s crucial you use these extinguishers correctly – they’re not suitable for kitchen fires, flammable gases or metals. 

For electrical fires, ensure the foam extinguisher has passed the 35kV conductivity test to guarantee your safety.

Carbon Dioxide (CO2) Extinguishers

Carbon dioxide (CO2) extinguishers are specifically designed for tackling fires involving electrical appliances and equipment. They work by displacing oxygen, thereby suffocating the fire without leaving any residue.

Suitability for Electrical Fires

CO2 extinguishers are an optimal choice for fires involving electrical equipment. 

Their non-conductive and non-corrosive discharge makes them safe for use on live electrical fires, such as in computer server rooms. 

It is critical to ensure that you are using a carbon dioxide (CO2) extinguisher for electrical fires because they avoid damage to sensitive electronic apparatus.

Special Considerations for Use

When deploying CO2 extinguishers, your safety is paramount. 

Be aware that these extinguishers work by suffocating the fire, which means they displace oxygen in the vicinity. 

This characteristic requires you to ventilate the area well after use. 

Also, because CO2 is released as a very cold gas, it carries a risk of cold burns, necessitating careful handling and proper distance from the discharge horn during use.

Dry Powder Extinguishers

Dry powder extinguishers are a potent solution for combatting various classes of fires, offering significant versatility. They are ideal for mixed-fire environments but require certain precautions during use.

Versatility Across Various Fire Types

Dry powder extinguishers are suitable for fighting Class A fires, which involve solid combustibles like wood and paper, Class B fires fueled by flammable liquids such as petrol or paint, and Class C fires involving gases like butane or methane. 

These extinguishers are also effective against electrical fires, as the powder is non-conductive. 

However, it’s crucial to turn off the power supply before using them on electrical fires to ensure your safety.

• Class A: Wood, paper, textiles
• Class B: Flammable liquids
• Class C: Flammable gases
• Electrical fires: Non-conductive suppression

The versatility of dry powder extinguishers can be attributed to their contents, typically a mix of mono-ammonium phosphate and other agents, forming the extinguishing powder, often referred to as BC powder.

Precautions and Handling

When handling dry powder extinguishers, be mindful of their properties. 

They disperse a fine powder that can obscure vision, potentially disorienting you during an emergency. 

It’s imperative to aim at the base of the fire and use a sweeping motion to stifle the flames effectively.

After extinguishing a fire, the residue left by dry powder extinguishers can be corrosive, especially in the presence of moisture. 

It’s therefore advised to clean up promptly after use to prevent damage to materials or equipment. 

Always ensure that you’ve received proper training before operating these extinguishers to maximise safety and efficacy.

Wet Chemical Fire Extinguishers

Wet chemical fire extinguishers are essential for locations where cooking oils and fats represent a fire hazard. These specialised extinguishers are designed to tackle Class F fires safely and effectively.

Targeted Fire Suppression for Cooking Risks

Wet chemical extinguishers are specifically manufactured to combat Class F fires, which involve cooking oils and fats commonly found in kitchens. 

Upon activation, they release a solution that not only cools the fire but also creates a soap-like film over the surface, preventing re-ignition. 

This makes them an ideal choice for environments such as restaurants, cafes, or anywhere deep fat fryers are in use.

Operation and Deployment

To operate a wet chemical fire extinguisher, you must carefully follow the manufacturer’s instructions. Typically, you should remove the safety pin, stand at a safe distance, and aim the extended applicator nozzle or lance at the base of the fire. 

Your aim is to cover the entire surface of the burning oil or fat with the wet chemical agent. By properly deploying a wet chemical fire extinguisher, you can swiftly suppress flames caused by cooking media, drastically minimising potential damage and ensuring safety.

Specialised Fire Extinguishers

In environments facing unique fire hazards, specialised fire extinguishers are a necessity. These extinguishers are designed to tackle fires involving specific materials that traditional extinguishers cannot address effectively.

Class D Extinguishers for Metal Fires

Class D fire extinguishers are essential for dealing with fires that involve combustible metals such as magnesium, aluminium, or lithium. 

Since water and other common extinguishing agents can react violently with these metals, Class D extinguishers use a dry powder agent that effectively smothers the fire and prevents the chemical reaction that can exacerbate the situation.

Water Mist Extinguishers for Diverse Use

Water mist extinguishers represent a versatile solution, as they can be used on various types of fires, including class F fires, which involve cooking oils and fats. 

The water mist emits a fine spray, which cools the flame and reduces the oxygen level, suffocating the fire without causing the spreading effect that can occur with traditional water-based extinguishers.

Selection, Installation and Maintenance

Selecting the right fire extinguisher is not just about fulfilling a legal requirement; it’s about ensuring the safety of your premises and people. 

Correct installation and regular maintenance are likewise essential to ensure that your fire extinguishers function properly when needed.

Choosing the Right Extinguisher

When selecting fire extinguishers, your decision should be informed by a detailed fire risk assessment. 

There are five main types you need to consider: water, foam, dry powder, carbon dioxide (CO2), and wet chemicals. 

The type of materials found in your premises determines the class of extinguisher that is appropriate. For example, a CO2 extinguisher is suitable for electrical fires, whereas a wet chemical extinguisher is designed for cooking oil and fat fires.

Installation Best Practices

Proper installation is critical for fire extinguisher accessibility and effectiveness. Install extinguishers:

• At the appropriate height: not more than 1.5 metres from the floor to the handle.
• Near room exits, areas of high risk, and along escape routes.
• With clear signage and instructions.

Each extinguisher requires commissioning, which is an initial survey and setup by a competent person to ensure it is fit for purpose and safely installed.

Maintenance and Inspection

Frequently Asked Questions

When it comes to fire safety, understanding your fire extinguisher options is vital. Here are the specifics on varying types of fire extinguishers, their uses, and features.

What categories of fire extinguishers are used for electrical fires?

For electrical fires, you need a non-conductive extinguishing agent. CO2 fire extinguishers and dry powder extinguishers are the most suitable for tackling these fires as they won’t conduct electricity back to you and exacerbate the hazard.

How do the different types of fire extinguishers correspond to fire classes?

Each fire extinguisher is designed for specific fire classes. For example, Class A fires involving solid materials such as wood require water or foam extinguishers, while flammable liquids in Class B fires are best extinguished by foam or CO2 extinguishers.

Could you explain the colour-coding system of fire extinguishers?

The colour-coding system on fire extinguishers in the UK is straightforward. 

Red indicates a water extinguisher, cream for foam, blue for dry powder, black for CO2, and yellow for wet chemical extinguishers, helping you quickly identify the correct type in an emergency.

What are the distinguishing features of CO2 fire extinguishers?

CO2 fire extinguishers are distinguished by their black label and are primarily used for electrical fires or flammable liquids. 

They suffocate the fire by displacing oxygen and don’t leave residue, which is crucial for environments with electrical equipment.

In what scenarios should a water fire extinguisher be used?

Water fire extinguishers, indicated by their red labels, should be used on Class A fires, which involve common combustibles like wood, paper, and textiles. They work by cooling the burning material to below ignition temperature.

How does a wet chemical extinguisher differ from others?

Unique for their yellow label, wet chemical extinguishers are designed specifically for Class F fires involving cooking oils and fats. 

They release a solution that reacts with the burning oil or fat to form a soapy, non-flammable surface, effectively extinguishing the fire and preventing re-ignition.