Fire extinguishers are fire suppression systems that put out small fires before they get out of hand. Irrespective of the type of fire, four main components are always present. These are, fuel, heat, oxygen, and a chain reaction. Fire extinguishers working principle is to remove one or more of these four components, and this puts out the fire.
Several fire extinguisher types are available sinc each fire class has a different fuel, heat source, and chain reaction. Each extinguisher is designed to fight specific types of fires, and you must understand the distinctions if it’s your job to fight fires at the workplace. Knowing which extinguisher to use can mean the difference between life and death in an emergency.
Types of Fire Extinguishers
A fire extinguisher is an external fire safety tool helpful for putting out or controlling small fire emergencies. There are five major extinguisher classes, each marked with a symbol that denotes the kind of fire it’s meant to put out. These are class A, B, C, D, and K fires. Getting the correct fire extinguisher types and uses for the given fire class is vital to avoid electrical shock, explosion, or fire spread.
Class A Fire Extinguishers
Class A fire extinguishers are used for typical combustibles like rubber, wood, paper, certain polymers, and textiles. This type of fire requires water’s heat-absorbing properties or specific dry chemicals’ coating properties.
Class B Fire Extinguishers
Class B fire extinguishers snuff fires caused by flammable liquids and gas-based combustibles like gasoline or oil. These fire extinguishers prevent the emission of flammable gases, which starve the flames of oxygen and break the chain of fire.
Class C Fire Extinguishers
Class C fire extinguishers are used on fires involving live electrical equipment and need electrically nonconductive extinguishing solutions. A CO2 extinguisher is the ideal extinguisher for Class C fires. This is because Carbon dioxide eliminates or displaces oxygen.
Class D Fire Extinguishers
Class D fire extinguishers are used on flammable metals such as magnesium, titanium, sodium, and others that need a suppressing medium that won’t react with the burning metal. These extinguishers are intended to choke the fire and keep the metal from reigniting.
Class K Fire Extinguishers
Class K fire extinguishers douse fires from cooking media (fats, grease, etc) in commercial kitchens because of the higher heating rates of vegetable oils in professional cooking units. These fire extinguishers operate on the saponification principle, which occurs when alkaline mixes like potassium acetate, potassium citrate, or potassium carbonate are added to burning frying oil or fat. When coupled with the fatty acid, the alkaline mixture forms a soapy foam on the surface, trapping gases and steam and suppressing the fire.
Fire Classification and Types of Agents Used in Fire Extinguishers
*Explain that different extinguishers use different agents to extinguish the fire. Then, explain how each works along with it’s pros and cons in the H3s below.
Water
Water fire extinguishers are the most common type of fire extinguisher and are suitable for class A fire hazards. A water fire extinguisher operates by cooling the fire’s fuel and removing the fire’s heating element.
Pros
- Simple to handle.
- Can put out the fire before it gets out of control.
- It’s safe to use
Cons
- It’s not ideal for electrical and metallic combustion.
- It cannot put out or control huge fires.
AFFF Foam
These extinguisher types are effective for class A and B flammable liquids but not for gaseous fires. These extinguishers spray foam that spreads and blankets the fire as it hits the air. This blanket stops the liquid’s vapors from rising to feed the flames, depriving it of fuel.
Pros
- Easy to handle
- Foam can coat liquid surfaces and prevent oxygen flow to a fire.
- Effective at controlling fire.
Cons
- It can only be used once
- The chemical must be mixed correctly for the foam to extinguish the fire successfully.
Carbon Dioxide (CO2)
The CO2 extinguisher does exactly that – it extinguishes CO2. Doing so eliminates oxygen from the fire, effectively snuffing it out. It’s perfect for use on class B fires that involve flammable liquids and electrical fires.
Pros
- Smothers fire quickly
- It may be used on active electrical equipment because it is non-conducting.
- Does not leave any residue and is less harmful to electrical equipment than powder.
Cons
- It’s an asphyxiate.
- It offers no guarantee against reigniting and has limited cooling capacity.
ABC Powder
A powder extinguisher blasts a very fine chemical powder, usually monoammonium phosphate. This blankets and suffocates the fire. Powder extinguishers are useful for class A, B, and C fires because they do not conduct electricity and can efficiently stop the chain reaction in a liquid or gas fire, which a water extinguisher cannot do.
Pro
- Excellent extinguishing power
- Can put out live equipment
- Frost-resistant
Con
- There is no cooling effect.
- High possibility of re-ignition
- Damages electrical devices
Deionised Water Mist
This type of extinguisher emits microscopic water molecules that combat the fire on multiple levels. When so much water is disseminated in such a small fog-like form, the oxygen level in the air is diminished, which aids in suffocating the fire. What distinguishes the water mist extinguishers is that the water has been de-ionized. As a result, it’s suitable for use in electrical fires because the de-ionized water does not act as a conductor.
Pros
- Suitable for classes A, B, C, and K fires.
- Environmentally friendly
- Safer and cleaner to use
Cons
- Water mist systems are less effective against shielded fires.
- It may take a longer time to extinguish the fire.
Wet Chemical
The wet chemical extinguisher is a specialized type primarily focused on class K fires involving cooking media like animal and vegetable fats or oils. These extinguishers use a potassium-based solution that effectively starts a two-pronged attack on fires. It first cools the fire with the liquid mist it sprays. Second, a thick soap-like substance forms on the liquid’s surface due to the chemical reaction between the solution and the cooking medium, closing it from re-ignition.
Pros
- Suitable for use with cooking fat and oil fires.
- Provides a cooling effect
- East to clean
Cons
- May be more expensive than other types of fire extinguishers
Service Free Fire Extinguishers (P50)
The P50 fire extinguishers are available in various types and have grown in popularity because they don’t require maintenance. They also have twice the lifespan of a conventional fire extinguisher. The P50 is a single-point extinguisher, meaning it has exceptional firefighting capability and can combat Class A, B, and C fires.
Pros
- Lesser impact on the environment
- Annual maintenance visits are not necessary.
Cons
- Compared to standard extinguishers, they cost more to buy.
How to Choose the Right Type of Fire Extinguisher?
Knowing which fire extinguisher to use is vital. The perfect fire extinguisher could mean the difference between paying for necessary safety gear and completely losing your business, office, house, or other structure to fire and smoke damage. Safety should always precede all other considerations, no matter the price. A protective system can be the ideal solution to meet your fire risk management goals. Not just any fire extinguisher will do. You need one that is suitable for your situation. Always remember the ABCs of different types of fire extinguishers when you get one.
