The LWF Blog
Fire Safety Engineering for Design – Foam Fire Suppression Systems – Part 290
June 8, 2026 9:21 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 289, LWF continued considering the testing that should take place before a foam fire suppression system is put online. In part 290, we talk about foam fire suppression with modern foam concentrates and premix foams.
Foam concentrates for use in a foam fire suppression system usually have a good lifespan when stored correctly. Modern foam concentrates have an expected shelf life of 10-20 years, some synthetic foams such as AFFF can last up to 25 years in ideal storage conditions. Protein based foams can last up to around 10 years and premix foam solutions retain their properties for around 1-3 years.
The useful lifespan of a foam concentrate depends upon how it is stored, with factors affecting its longevity:
- Storage temperature
- Exposure to sunlight
- Contamination
- Ingress of moisture
- If the container is well-sealed
- Storage tank material compatibility
NFPA 11 states that concentrates stored in their original sealed containers and kept within manufacturer temperature limits can be stable for over a decade.
The distinction between foam concentrate and premix foam is important, especially in relation to lifespan and storage. Foam concentrate is the undiluted chemical for foam fire suppression before water is added. It is generally stored in drums, tanks or bladder tanks.
Premix foam is already mixed with water at the required ratio and is, generally speaking, far less stable for long term storage. Water may introduce bacteria or contamination and the chemical composition may change, separate or degrade over time. Corrosion is possible inside storage tanks. Fluctuations in temperature, such as freeze and thaw cycles, can damage the mixture. Premix solutions should be subject to frequent quality testing and be replaced every 1-3 years.
Annual testing of foam is recommended by standards such as NFPA 11 and NFPA 25, and regular appropriate testing is recommended in BS EN 1568 performance criteria and manufacturer specifications.
A small sealed sample of the original foam concentrate should be taken upon purchase and kept for future comparisons, this is known as a ‘retained sample’. Both the end user and the foam manufacturer may keep retained samples. Should the majority of the foam later deteriorate or fail testing, the foam sample allows checks to be made on issues such as supply, contamination, storage etc.
While testing can appear to be an administrative function designed to protect expensive purchases, it is actually essential for fire safety. Foam can appear normal and yet fail in a real fire situation.
In part 291 of LWF’s series on fire engineering we will look at the necessary documentation for foam fire suppression systems. 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.