The LWF Blog
Fire Safety Engineering for Design – Foam Fire Suppression Systems – Part 280
March 30, 2026 8:50 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 279, LWF talked about subsurface foam units for fixed roof oil storage tanks. In part 280, we discuss foam water sprinklers.
A foam water sprinkler is a type of fire protection device that is designed for areas where flammable/combustible liquids are stored or used, such as fuel storage, processing plants, chemical handling facilities etc.
While a standard water sprinkler is designed primarily to cool and suppress fires using water, a foam sprinkler applies a mixture of water and foam concentrate aspirated with air which creates a foam blanket capable of smothering a fire.
Foam water sprinklers usually have open nozzles rather than heat-activated sprinkler heads. This means that when the system is activated by a fire detection system or manually, the foam mixture flows simultaneously through all the nozzles in the hazard area. They are most commonly placed in areas of process equipment, fuel transfer points or storage areas where rapid fire spread is likely and immediate coverage is essential.
The design of the sprinkler includes an air-induction body. When the foam solution (water/concentrate mix) is discharged, it passes through the induction body. The mixture flows at high velocity creating a pressure drop, which draws in air through specially designed openings. As the air mixes with the foam mixture, it becomes aspirated and produces the expanded foam necessary to form the foam blanket.
The foam then strikes a deflector plate which is positioned at the outlet of the nozzle, this spreads the foam outward in a circular pattern and helps to ensure even distribution over the protected area. It is designed so the foam settles gently and with minimal agitation, which is essential when dealing with flammable liquid spills/flammable liquid fires. The resulting foam blanket smothers the fire by blocking its access to oxygen, suppresses vapours, cools by absorbing heat and helps to stop re-ignition once the fire is under control.
Any fire suppression system must be purpose designed for the specific hazards and environment in which it will work.
In part 281 of LWF’s series on fire engineering we will talk about water sprinklers and sprayers. 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.