Safe Storage of Flammable Liquids Outdoors

26th February 2014

You must install a safe, external flammable storage area for your highly flammable chemicals outdoors. The biggest risk with the storage of highly flammable liquids is obviously fire and the negative contribution that your stock of HFL’s would make to any fire on your premises. Your aim therefore is to store your highly flammable chemicals outdoors in a manner that will reduce the risk of them contributing to or increasing the severity of a fire on site.

Volume and Space Recommendations

The volume of HFLs that you have to store and the proposed location of your flammable store is very important. The HSE have a guidance document HS(G)51 which has a table of volumes of HFLs stored vs. the minimum distance that your Flammables Store can be located away from an occupied building, source of ignition, LPG tank, boundary, etc. For example, if you are storing between 1,000 and 100,000 litres of HFL, the minimum separation distance is 4 metres.

If you cannot satisfy the minimum separation distance, then your Flammable Chemical Storage Unit must be fire protected/fire rated. You can achieve this through various construction methods using traditional concrete construction or by purchasing a Flammable store which has a stated fire protection level. These levels are measured by time, e.g. 60 minute/1 hour fire protected store. A flammable storage cabinet with 60 minutes fire protection should mean that if there were a fire on your premises, your flammable chemicals will be insulated from the fire for 60 minutes, giving you and your staff time to exit the premises safely and time for fire fighters to begin tackling the fire.


Your store should be bunded to retain any spillages which may occur .The bund capacity should be either 110% of the capacity of the largest container in your store or 25% of the total volume to be stored, whichever is the greater. Ventilation is also very important to disperse any flammable vapours from your flammables store. The vapours from HFLs are heavier than air so vents should be at floor level and/or forced extraction should be designed to pull vapours from floor level.

Potential Risks

A risk assessment will need to be carried out on your flammable storage cabinet, to determine if it needs to be zoned as a hazardous area. Where there are flammable vapours present, and any electrical equipment installed in the store, it will need to be Ex/atex rated for flammable atmospheres. See the Applied Measurements Ltd. website for further information on ex/atex ratings.

By ensuring adequate flammable liquid storage, you can reduce the number of workplace accidents as well as the potential damage caused by any unfortunate disasters.

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