How to Choose a Fire Extinguisher for your Business

Posted on 29/11/2017

Fire extinguishers are an essential part of the fire safety provisions of all buildings, however it must always be remembered that they are only intended to put out small fires.

As the complexity of buildings increases so does the need for effective fire protection systems such as fire alarms, emergency lighting, evacuation routes and portable fire fighting devices. As buildings are extended and changed so should the corresponding systems.  This is a critical and complex topic and not all aspects can be covered in a single article.

The information that follows is a basic guide to fire extinguishers. Please always seek professional advice when choosing fire extinguishers and other fire protection systems for your business and home. 

What are the Classes of Fire?

Fires are classified according to the kind of fuel involved in a fire.  The ability of a fire extinguisher to put out a fire is indicated by letters relating to the relevant fire classes.
Class of Fire 
CLASS A - Involving solid materials such as wood, paper or textiles.  
CLASS B - Flammable liquids, such as petrol, diesel and paraffin. Not alcohol or cooking oil. 
CLASS C - Flammable gases, such as LPG, Propane, Butane and natural gas 
CLASS D - Flammable metals, such as magnesium swarf 
CLASS F - Cooking fats and fryer oils  
Electrical Such as an electrical appliance or wiring
Suitable Fire Extinguisher  
It is important to remember that extinguishers are not designed to fight large fires. 

CLASS A - Water, foam or multi-purpose dry powder extinguishers
CLASS B -   Foam
CLASS C  -  Powder
CLASS D -  Specialist Powder
CLASS F - Wet chemical 
Electrical -   Powder, CO2

Choosing Fire Extinguishers 

CO2 fire extinguishers

These units are suitable for class B fires such as flammable liquid fires and especially effective on fires in electrical equipment.  CO2 leaves no residue once the fire is extinguished.  They are often installed next to foam extinguishers in offices with computers. The size of CO2 units is stated in kg (of CO2 gas) and the portable CO2 extinguishers weigh 2 and 5 kg.  Never hold the horn of a CO2 extinguisher when operating it as they can cause ice burns if the horn is not double-insulated.
A specialist version of the CO2 extinguisher is anti-magnetic and is installed in areas of high magnetic activity.

Water fire extinguishers

These can only be used on class A fires of solid combustible materials, such as wood, fabric and paper. The water penetrates burning materials to cool down the fire, which extinguishes the fire and stops it re-igniting. It is dangerous to use water fire extinguishers on anything other than a class A fire. They cannot be used on electrical fires. 
A new development are the 'dry' water mist extinguishers, which can be used on class A, B, C and F fires and are very easy to use. These can be installed in buildings, where extinguisher training of all residents/staff is not feasible, such as in HMOs etc. Dry water mist is suitable for A, B, C and F class fires.  

Foam fire extinguishers

These are used on burning solids (Class A) and liquid fires (Class B), such as petrol and other flammable liquids. They are excellent in offices and homes. The discharged foam forms a layer on the burning material thereby starving the fire of oxygen. Foam extinguishers are used in office environments, as they offer a reasonably wide cover without the clean-up problem of a powder extinguisher. Foams can be used safely on electrical items, as long as they are 35kV tested and you keep a safety distance of 1m. 
Foam units are lighter than an equivalent water extinguisher and consequently are more manageable for staff to use and tackle a small fire.

Wet chemical fire extinguishers

Wet chemical and ABF foam extinguishers are used on fat fires and deep fat fryer fires (Class F). The chemical of the wet chemical bonds with the burning fat and stops the supply of oxygen to the fat. Wet Chemical extinguishers are used in professional kitchens, while ABF can be used in domestic kitchens. 

Powder fire extinguishers

Dry powder fire extinguishers can be used for class A (burning solids) class B (burning liquids) and class C (burning gas) fires. They cannot be used on fat fires and deep fat fryer fires. Their powerful jet would spread the burning fat. They are known to cause breathing problems and so their use in small spaces is not recommended. The residue of the powder is messy and difficult to clean up after use. 
Powders are the most multi- purpose and will extinguish a fire quickly. They have little cooling effect and therefore the fire can re-ignite if not completely out. 


What is British Standard 5306-3?

BS 5306-3 is a Code of Practice for best practice in the commissioning, installation, servicing and maintenance of fire extinguishers.  
British Standard 5306-3 recommends that extinguishers be commissioned on-site by a competent person. 

How Often should my fire extinguisher be inspected?

It is essential that extinguishers are inspected regularly for corrosion, damage or discharge. 
Extinguishers should be inspected visually every month. Check the equipment is in the proper position and that it had not lost pressure or been discharged. Always check the hose or horn. Check monthly that the tags and pins are still in place.  If these are missing the extinguisher needs servicing before putting it back into service.
This is very important, extinguishers are pressurised containers and if not maintained correctly can explode causing serious injury or even death. 

Why does my extinguisher need a service if I have not used it?

Extinguishers can lose pressure and can suffer rust inside the canister.  It is possible for valves to stick and seals deteriorate which would affect the performance of the extinguisher in an emergency.  It is essential therefore that extinguishers are regularly checked visually and serviced by a competent person. If an extinguisher has been discharged even if only partly, it needs recharging in accordance with the manufacturers instructions before it can be put back into service. 

Do Fire Extinguishers Need an Annual Check? 

Yes they do. All types of extinguisher need a basic check on an annual basis. 

How often should fire extinguishers be maintained?

Weekly - check by the ‘responsible person’ in your business.
Monthly - Visual inspection by the ‘responsible person’ in your business.
Annually - Basic service by Competent Person. In high risk locations or corrosive environments this should be more frequent. 
Every Five Years - Extended service & overhaul by competent person 

Do CO2 Extinguishers require an extended service every 10 years?

Yes. They must be refurbished every 10 years.  A complete strip down and a hydraulic pressure test is required to meet Pressure Systems Safety Regulations 2000. No fire extinguisher in use should be more than 20 years old. 

What is the definition of a ‘Responsible Person’?

The person who is responsible for risk assessments in a business is known as the Responsible Person. They must also implement and maintain appropriate and adequate fire safety systems. This is usually the owner, occupier or employer in a premises. 

What qualifications does my Fire Extinguisher installer need?

Always ensure that your installer has a minimum of “BAFE” accreditation as there is no mandatory accreditation required and this may leave you as a building owner exposed if your contractor is unqualified or inexperienced.  
Find out more about Fire Extinguishers or further information on Fire Alarms and Emergency Lighting use this link. Or contact us further information.