The LWF Blog

Fire Safety Engineering for Design – Foam Fire Suppression Systems – Part 287

May 18, 2026 9:56 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 286, LWF discussed foam system design. In part 287, we talk about the components and materials of a foam fire suppression system.

The materials used to construct a foam fire suppression system should be suitable for the purpose to which it will be put. The foam concentrates used may be chemically aggressive and, as a result, galvanised steel (zinc-coated pipe) is usually unsuitable because the foam can react to the zinc layer and cause corrosion of the pipes, contaminate the foam and reduce the overall effectiveness of the system.

To avoid this type of issue, a foam fire suppression system commonly uses black (carbon) steel pipes, although stainless steel or copper alloys may be necessary for certain foam types such as some synthetic foams.

Manufacturers of foam concentrates can usually be relied upon to specify compatible materials for their own formulations.

The foam concentrate used in a foam fire suppression system should not be allowed to remain within the pipework, due to degradation and stagnation issues. The separation of the foam components and thickening or increased viscosity can lead to a loss of firefighting effectiveness. For this reason, each system should be designed to ensure there are no areas with ‘no flow’ to avoid trapping of concentrate. The lines of systems should be self-draining or regularly flushed. The concentrate should be stored in tanks rather than in the pipework of the system.

A foam fire suppression system usually operates at similar pressures to conventional sprinkler systems. This means the designer of the foam system may use established standards, such as similar pipe ratings, fittings, valves as they would in a sprinkler system. The components must be able to effectively handle normal operating pressure as well as surges during activation. It should be borne in mind by the system designer that larger pipes reduce friction loss, the pump should be capable of working with higher viscosity fluids and the effects of temperature on the foam must be considered.

After the system is designed and installed, the pipework should be properly supported in place, this helps to prevent vibration damage, stress at pressure points such as joints and movement during discharge of the system.

The system should then be pressure tested to 1.5x the maximum anticipated working pressure to ensure structural integrity and to check for leaks.

In part 288 of LWF’s series on fire engineering we will look at the testing that should take place before a foam fire suppression system is put online. 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.