Fire Safety and Fire Extinguishers At Work

Fire extinguishers are required in every workplace. However, it’s important to note that not all fire extinguishers can be used on all fires. In this blog we are going to look over the types of fires, the types of fire extinguishers, and which fire extinguishers to use on which fires.

Different Fire Classifications

In the UK, fires are typically classified into different classes based on the type of materials or substances involved. The fire classes in the UK are commonly referred to as the “European fire classes” and are designated by a letter:

• Class A: This class includes fires involving solid materials such as wood, paper, textiles, and plastics. These fires usually leave behind ash after burning.
• Class B: Class B fires involve flammable liquids such as petrol, diesel, oils, solvents, and alcohol. These fires can spread rapidly if not properly controlled.
• Class C: This class covers fires involving flammable gases, such as natural gas, propane, butane, and methane. These fires can be particularly dangerous due to the potential for explosions.
• Class D: Class D fires involve metals, such as magnesium, titanium, sodium, and potassium. These fires require specific extinguishing agents designed for suppressing metal fires.
• Class F: Class F fires are specific to cooking oils and fats, typically found in commercial kitchens. The high temperatures and rapid spread of these fires require specialised extinguishing agents.

It’s worth noting that the classification system may vary in certain contexts, and there may be additional classifications or subcategories depending on specific applications or industries.

Different types of fire extinguishers

In the UK, fire extinguishers are categorised into different types based on the classes of fires they are designed to tackle. The most commonly used fire extinguisher types in the UK are as follows:

• Water Extinguishers
• AFFF (Aqueous Film Forming Foams) Foam Extinguishers
• Carbon Dioxide (CO2) Extinguishers
• Dry Powder Extinguishers
• Wet Chemical Extinguishers

Specialist Extinguishers: In addition to the above types, there are specialised extinguishers for specific applications, such as fire blankets (to smother small fires or wrap around a person), water mist extinguishers, and fire extinguishers for specific industries.

It’s important to note that the choice of fire extinguisher should be based on the specific fire risks present in the environment, as well as compliance with local regulations and guidelines. Proper training on the correct use of fire extinguishers is also essential for effective fire safety.

Water extinguishers

A water fire extinguisher is designed to tackle Class A fires, which involve solid materials such as wood, paper, textiles, and plastics. Water extinguishers are one of the most common types of fire extinguishers and are widely used in various settings, including homes, offices, schools, and public buildings.

Here’s how a water fire extinguisher works:

• Extinguishing Agent: A water extinguisher contains water as its main extinguishing agent. The water is pressurised within the extinguisher, allowing it to be discharged forcefully when the extinguisher is activated.
• Cooling Effect: Water extinguishers work by reducing the temperature of the fire. When you aim the extinguisher at the base of the flames and spray water onto the burning material, the water absorbs heat from the fire, effectively cooling it down. By lowering the temperature below the ignition point, the fire is suppressed and eventually extinguished.
• Limitations: While water extinguishers are effective on Class A fires, they should not be used on fires involving flammable liquids (Class B), electrical equipment (unless it is a water mist extinguisher specifically designed for electrical fires), or cooking oils and fats (Class F). Using water on these types of fires can be dangerous and may worsen the situation. It is crucial to identify the correct fire class before attempting to use an extinguisher.

It’s important to note that water fire extinguishers can be heavy and should be handled properly to avoid strain or injury. Regular maintenance, inspection, and recharging of the extinguisher are also necessary to ensure its reliability and functionality when needed.

AFFF (Aqueous Film Forming Foams) Foam Extinguishers

Foam fire extinguishers are designed to tackle Class A and Class B fires, making them versatile for various fire scenarios. They are commonly found in settings such as offices, industrial facilities, workshops, and garages. Here’s how foam extinguishers work:

• Extinguishing Agent: Foam extinguishers contain a mixture of water and foam concentrate. The foam concentrate is typically based on synthetic detergents or protein-based agents. The extinguisher pressurises the water and foam concentrate, allowing them to be expelled when activated.
• Smothering Effect: When discharged, the foam extinguisher forms a thick foam blanket that covers the burning materials. This foam blanket prevents oxygen from reaching the fuel source, effectively smothering the fire and suppressing the flames. The foam also helps cool the fire by absorbing heat.
• Limitations: Foam extinguishers are not suitable for all fire classes. While they are effective on Class A fires (involving solid materials) and Class B fires (involving flammable liquids), they should not be used on electrical fires (unless specified as safe for use on electrical equipment). Additionally, foam extinguishers may not be suitable for fires involving flammable gases, metals, or cooking oils (Class F). It’s crucial to understand the specific fire class before attempting to use a foam extinguisher.
• Cleanup: After using a foam extinguisher, it’s important to clean up the foam residue properly. The foam can be corrosive, so it’s advisable to consult professional cleaning services or follow appropriate guidelines for cleanup and disposal.

Regular maintenance and inspections are essential to ensure the foam extinguisher is in proper working condition. This includes checking the pressure gauge, ensuring the nozzle or hose is clear, and verifying the extinguisher’s overall integrity.

Carbon Dioxide (CO2) Extinguishers

Carbon Dioxide (CO2) fire extinguishers are commonly used to tackle Class B fires (involving flammable liquids) and electrical fires. They are widely found in offices, server rooms, laboratories, and areas with sensitive electrical equipment. Here’s how CO2 extinguishers work:

Extinguishing Agent: CO2 extinguishers contain carbon dioxide gas stored in a pressurised cylinder. When the extinguisher is activated, the pressurised CO2 is expelled in the form of a gas.

• Smothering Effect: Carbon dioxide extinguishes fires by displacing oxygen. When you direct the CO2 gas towards the fire, it creates a dense cloud that envelops the flames. By replacing the oxygen, the CO2 suffocates the fire, effectively extinguishing it.
• Non-Conductive: One significant advantage of CO2 extinguishers is that the gas is non-conductive, making them safe for use on electrical fires. Unlike water or foam extinguishers, CO2 does not conduct electricity, reducing the risk of electrical shock when used on live electrical equipment.
• Limitations: While CO2 extinguishers are effective on Class B and electrical fires, they are not suitable for all fire classes. They are not designed for use on Class A fires (involving solid materials) or Class F fires (involving cooking oils and fats). CO2 extinguishers may not have a cooling effect, so there is a possibility of re-ignition if the fuel source is still hot. It’s essential to identify the specific fire class before using a CO2 extinguisher.
• Safety Considerations: It’s crucial to be aware that CO2 displaces oxygen and may cause asphyxiation in confined spaces with poor ventilation. Therefore, it is recommended to use CO2 extinguishers in well-ventilated areas and to evacuate the area if necessary.

Regular maintenance, inspections, and recharging are necessary to ensure the CO2 extinguisher is in proper working order. This includes checking the pressure gauge, ensuring the horn or nozzle is clear, and verifying the overall condition of the extinguisher.

Dry Powder Extinguishers

Dry powder fire extinguishers are versatile and effective for tackling various types of fires. They are commonly used in settings where multiple fire hazards exist, such as industrial facilities, workshops, garages, and kitchens. Here’s how dry powder extinguishers work:

Extinguishing Agent: Dry powder extinguishers contain a fine powder composed of different chemical agents, such as monoammonium phosphate, sodium bicarbonate, or potassium bicarbonate. The powder is stored in a pressurised cylinder.

• Chemical Reaction: When the extinguisher is activated, the pressurised powder is expelled as a cloud of fine particles. The chemical agents in the powder work by interrupting the chemical reaction of the fire. The powder forms a barrier between the fuel source and the oxygen, inhibiting the fire’s ability to sustain itself.
• Smothering and Cooling Effect: Dry powder extinguishers have a smothering effect on the fire, preventing the access of oxygen to the fuel. Additionally, the fine particles of the powder can absorb heat, providing a cooling effect.
• Multi-Class Capability: Dry powder extinguishers are effective on a range of fire classes, including Class A (solid materials), Class B (flammable liquids), Class C (flammable gases), 
• and electrical fires. This versatility makes dry powder extinguishers suitable for situations where the specific fire class is uncertain or where multiple fire hazards exist.
• Limitations: Although dry powder extinguishers are effective, they have some limitations. The powder can create a cloud that reduces visibility and can be inhaled, so proper ventilation is crucial. Additionally, the powder may not penetrate deep-seated fires or provide sufficient cooling effect for certain materials. It may also leave behind a residue that requires thorough cleanup after use.
• Safety Considerations: Dry powder extinguishers may not be suitable for use in enclosed spaces, as the powder can become suspended in the air and restrict visibility. Moreover, they are not recommended for use in areas with sensitive electronic equipment, as the powder can cause damage.

Regular maintenance and inspections are essential to ensure the dry powder extinguisher is in proper working condition. This includes checking the pressure gauge, ensuring the nozzle or hose is clear, and verifying the overall integrity of the extinguisher.

Wet Chemical Extinguishers 

Wet chemical fire extinguishers are specifically designed to tackle Class F fires, which involve cooking oils and fats. These extinguishers are commonly found in commercial kitchens, restaurants, and other food preparation areas. Here’s how wet chemical extinguishers work:

• Extinguishing Agent: Wet chemical extinguishers contain a specially formulated solution that combines water with a potassium-based chemical agent, such as potassium acetate or potassium citrate. The solution is stored in a pressurised cylinder.
• Saponification: Wet chemical extinguishers work by a process called saponification. When the extinguisher is activated and the solution is expelled, it creates a fine mist or spray. This mist settles on the burning cooking oil or fat, forming a soapy layer.
• Cooling and Smothering Effect: The wet chemical solution has a dual effect on Class F fires. Firstly, it cools the burning oil, reducing the temperature and heat of the fire. Secondly, the soapy layer created by the chemical reaction acts as a barrier, smothering the flames and preventing re-ignition.
• Limitations: Wet chemical extinguishers are specifically designed for Class F fires and are not suitable for use on other fire classes. They should not be used on fires involving flammable liquids (Class B), electrical fires, or fires with other types of fuels. It’s crucial to identify the specific fire class before attempting to use a wet chemical extinguisher.
• Cleanup: After using a wet chemical extinguisher, it’s important to clean up the residue left behind. The soapy solution can be slippery and may require appropriate cleaning procedures to ensure a safe environment.

Regular maintenance and inspections are necessary to ensure the wet chemical extinguisher is in proper working order. This includes checking the pressure gauge, ensuring the nozzle or hose is clear, and verifying the overall condition of the extinguisher.

Ensuring safety in the event of a fire

Remember, fire safety is paramount. If a fire becomes too large, smoky, or uncontrollable, evacuate the area immediately, alert others, and contact the emergency services.

One of the best ways to ensure safety in the event of a fire, is to ensure all staff are trained regularly on fire safety training. In addition, you should ensure you have the correct number of fire wardens trained in your business. As a general rule of thumb, you should have 1 fire warden for every 5-10 employees. You should also ensure you have enough fire wardens trained to cover annual leave and/or sickness.

Try our Fire Awareness Training course today – https://procompliance.co.uk/fire-awareness-safety-training/

Try our Fire Warden Training course today – https://procompliance.co.uk/fire-warden-training/

Or contact the team at ProCompliance at info@procompliance.co.uk, or on 01344 957 700. We will be happy to offer support and guidance on general fire safety at work.