The LWF Blog

Fire Safety Engineering for Design – Foam Fire Suppression Systems – Part 271

January 26, 2026 11:05 am

LWF’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 270, LWF discussed alcohol-resistant foam in more detail, as well as covering Class A foam. In part 271, we talk about fluorine-free foams and C6 foams.

Fluorine-free Foam (FFF or F3)

In recent years, fluorine-free foam has become more popular, due to the environmentally-friendly composition designed to replace traditional AFFF foams, which contain harmful PFAS. FFF is biodegradeable and reduces the risks to human health and wildlife.

The performance of fluorine-free concentrate is usually reviewed and if a large amount is to be purchased, a recognised fire test is conducted to ensure it is suitable for the intended application. The test will check suitability for extinguishing, vapour suppression and burn-back performance.

BS EN 1568 identifies appropriate tests, along with testing standards from LASTFIRE (Large Atmospheric Storage Tank Fires) which is a consortium of international oil and storage companies who reviewed the risks of fires in storage tanks and developed best industry practice based on the findings of the associated research, academic studies and experience.

C6 Foams

C6 is a firefighting foam which contains short-chain PFAS to replace longer-chain foams (C8). Initially they were seen as an alternative that was less toxic and bioaccumulative. However, restrictions on PFAS-containing products are becoming widespread and it is thought C6 foams (including AFFF) will be restricted or banned in the EU and UK in the next few years (likely by 2030).

C6 uses 6 carbon fluorosurfactants instead of 8. C8 foams were used in Teflon and Scotchguard which were linked to PFOA and environmental persistence.

With regards to performance, overall the knockdown and seal, burnback resistance and performance in sub-optimal conditions (like high winds, low temperatures etc.) is reported to be good.

While the environmental impact of such products must be taken into account, it is currently the case that C6 is a more appropriate foam for use in tough conditions, such as offshore installations, due to resilience to wind, seawater and extreme cold. Some fluorine-free foams are not suitable for forceful application and harsh elements.

Hypothetically, it may be that the restrictions or bans on C6 lead to a situation similar to that of Halon. While production is banned, Halon is permitted for use in certain critical and strictly-monitored circumstances where no other option is as effective and until a suitable alternative is found and accepted.

In part 272 of LWF’s series on fire engineering we will begin to talk about foam proportioning. 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.