Choosing the right extinguisher for your business is not as straight forward as you may think. The quantity and type required depends on the nature of the business and the risks that have been identified in the fire risk assessment.

Types of fire are divided up into classes depending on the type of fuel involved in the fire.

  • Class A fires involve solid fuels, such as wood
  • Class B fires involve flammable liquids, such as petrol
  • Class C fires involve gas
  • Class D fires involve metals, such as potassium or magnesium
  • Class F fires involve cooking oils

Special attention must be given to fires where electrical equipment is involved due to the risk of electricity being conducted by the fire fighting medium used to extinguish the fire.

Each extinguisher is given a rating, for example 13A. The letter refers to the fuel type on which the extinguisher is used and the number refers to the size of the fire. So an extinguisher that is 21A rated will have the capability to fight a larger fire than a 13A extinguisher for the same class of fire, in this case solid fuels, such as wood.

It is very hard to say how many extinguishers you will require without surveying the premises. As a very rough guide you will need at least one water based extinguisher, such as water, water with additive or foam of at least 3ltr or more, for every 200 square metres or 2000 square feet. However, every floor must have at least two extinguishers.

Replacing existing extinguishers

As long as there have not been any changes to the building or its use then this should be straight forward. Make sure that you purchase extinguishers with the same rating as the old one. It is worth making sure that the existing extinguishers were installed by a competent person and that the extinguishers are of the correct type for the location, as for example powder extinguishers are no longer permitted for office use.

Buying and installing extinguishers for the first time

If you are installing extinguishers in a new building or a building that has been renovated and its use having changed, it is advisable to have a site survey carried out to establish your requirements. Our parent company, Safelincs, offers site surveys and installation of extinguishers. The site survey will also highlight where the extinguishers need to be sited to adhere to the relevant legislation.

Ongoing maintenance

Extinguishers should be installed by a BAFE registered extinguisher engineer. This will ensure that the engineer works to the latest standards and legal requirements. Once the extinguishers have been installed, a monthly visual inspection should be carried out by your staff. When completing the monthly inspections you will need to check for any signs of damage to the exterior of the extinguisher body, that the hose is not blocked and, if there is a pressure gauge that its needle still points to the green area of the gauge. Check that all the extinguishers are located where they should be. The monthly check should be recorded, signed and dated.

Once a year the extinguishers should be serviced by a BAFE qualified extinguisher engineer. At intervals of mostly 5 years the extinguisher will need an extended service which requires discharging and refilling. Your service engineer will be able to advise you when your extinguishers are due.


Reviewed: 28/02/2019 (doc:201 V1.0). Our articles are reviewed regularly. However, any changes made to standards or legislation following the review date will not have been considered. Please note that we provide abridged, easy-to-understand guidance. To make detailed decisions about your fire safety provisions, you might require further advice or need to consult the full standards and legislation.