The LWF Blog
Fire Safety Engineering for Design – Foam Fire Suppression Systems – Part 266
December 22, 2025 11:10 amLWF’s Fire Safety Engineering blog series is written for Architects, building designers and others in the construction industry to highlight and promote discussion on all topics around fire engineering. In part 265, LWF talked about third-party certification and approved contractors for sprinkler system installations. In part 266, we discuss a different kind of fire suppression system – foam systems.
Standards for Foam Fire Suppression Systems
BS EN 13565-2 is the British Standard covering Foam Systems and their design, construction and maintenance.
There are other standards which can provide useful information for foam-based fire suppression systems:
BS EN 1568-1 – a standard looking at foam concentrates and the specification for medium-expansion foam concentrates for surface application to water-immiscible liquids.
NFPA 11 is a standard relating to low, medium and high expansion foam and covers the design, installation, operation, testing and maintenance of foam systems for fire protection. The NFPA is a US organisation. NFPA 16 was a standard for the installation of foam-based fire suppression systems but has been withdrawn in 2020 and its contents included in NFPA 11.
What are Foam Systems used for?
Foam systems suppress fire that might start in areas with flammable liquids. For example, flammable liquid pool fire hazards or defined flammable liquid hazards, including flammable liquid storage tanks and containers.
A foam system may also be effective against fires of Class A materials which are ordinary combustibles.
The choice of foam concentrate and foam proportioning system should vary according to the type of system, water supply pressure and whether or not a central supply is utilised to serve a number of hazard areas from the central source.
Foam concentrate is, as the name suggests, a concentrate which is added to water at a specific proportion ratio. For example, 3% concentrate to 97% water (although this ratio can vary depending upon the foam solution used and the hazards being protected). The mix is aspirated with air to produce foam bubbles before being applied to the surface of the flammable liquid and ‘suffocating’ the fire (not allowing oxygen to reach the liquid on fire). Fire needs oxygen to continue to burn and to grow, and so the fire is suppressed by the aspirated foam mixture.
In part 267 of LWF’s series on fire engineering we will continue to talk about how foam suppresses and extinguishes fire. In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.
Lawrence Webster Forrest has been working with their clients since 1986 to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact the LWF office on 0800 410 1130.
While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.