Types of fire extinguishers and how they work

Fire safety & prevention

Posted by
Jessica Twigg

2nd October 2019

Types of fire extinguishers and how they work - TIS

Types of fire extinguishers and how they work

There are several types of fire that each require a different method of extinguishing. So, it can be difficult to know which fire extinguisher you need.

Fire safety is crucial for any business, so we have put together a helpful guide of the different types of fire extinguishers to help you decide which one is right for your business.

Before we get started, it’s important to understand the six classes of fires as each type requires a different fire extinguisher. Using the incorrect extinguisher can, in some cases, worsen the fire increasing the risk to your business.

Types of fire extinguishers and their uses

Water Fire Extinguisher

Water fire extinguishers should only be used for fires caused by combustible materials, such as paper or wood. These fires are also known as a Class A fires. Under no circumstances should water extinguishers be used on liquid or electrical fires as it may worsen the problem.

How do water fire extinguishers work?

While there are several types of water fire extinguishers, their basic function is to cool the temperature of the flames, which puts out the fire.

Water fire extinguishers are often chosen as they cover a greater surface area, extinguishing the fire quickly. While water mist extinguishers use microscopic water particles cooling both the flame and surrounding gases and displacing oxygen by evaporation.

Foam Fire Extinguisher

Foam extinguishers are only useful for combatting fires from combustible materials (Class A) and flammable liquids (Class B). This means they aren’t recommended for domestic use.

How do foam fire extinguishers work?

Foam extinguishers use a water-based material that foams when it comes into contact with the fire. This is so it can float on top of flammable liquids, suffocating the fire.

Dry Powder Fire Extinguisher

Dry powder extinguishers are the most versatile type of fire extinguisher, being able to tackle all classes of fire except for those caused by oil (also known as Class F). This makes them the only extinguisher suitable for flammable gases (Class C) and metals (Class D).

How do dry powder fire extinguishers work?

A fine powder smothers the fire, preventing more combustible materials getting close to the hot flames. The powder also cools the flames to stop further chemical reactions from occurring.

Carbon Dioxide Fire Extinguisher

Carbon Dioxide (CO2) extinguishers are best for Class B and Electrical fires. This makes them extremely useful in offices with computers and other electrical equipment.

How do CO2 fire extinguishers work?

The CO2 dispelled from the extinguisher displaces the oxygen in the air, suffocating the fire. However, it is incredibly important that the fire is fully extinguished as once the CO2 has run out, as the oxygen may reignite the flame.

Wet Chemical Fire Extinguisher

These extinguishers should only be used on fires caused by combustible materials and oils. As the only type of extinguisher that can combat an oil fire, they are necessary in any building with a deep fat fryer.

How do wet chemical fire extinguishers work?

The fine mist cools the flame front while potassium salts in the chemicals create a soap-like substance on top of the oil that smothers the fire.

P50 Fire Extinguisher

The P50 fire extinguisher uses an Aramid fibre Kevlarâ type material to create a super strong and lightweight extinguisher. It covers multiple fire risks that would usually require 2 or 3 different types of fire extinguisher.  This means you need fewer extinguishers on your premises which in turn reduces costs and avoiding confusion in a panic situation.

How do P50 fire extinguishers work?

P50 fire extinguishers are available in foam, F Class and powder variations, using similar methods as above to prevent the fire from spreading.

What Regulations Do I Need to Follow?

British standards require businesses to have a minimum of two Class A extinguishers on each storey of a building. However, it is also good practice to have a CO2 extinguisher on every floor if you use electrical equipment, such as computers.

For more specialist fire threats such as deep pan fryers, the extinguisher should be placed near the source of the threat.

Fire extinguishers should be placed near a fire alarm trigger system or next to a fire exit – while ensuring it does not restrict access.

It is also important that your extinguishers are regularly serviced to ensure they are in full working condition at all times.

What to Consider When Buying a Fire Extinguisher

As there are many different types of fire risks, each requiring a different extinguisher, it is important to make sure you have chosen the right extinguisher for your business and the fire threats it poses.

It is also crucial to consider the positioning of your extinguishers throughout your premises, as they need to be easily accessible in an emergency as well as meeting regulations.

Do you need help deciding which extinguishers are right for your business and where is best to place them? Get in touch with our team today.