The LWF Blog
Fire Safety Engineering for Design – Sprinkler Systems – Part 240
June 23, 2025 10:48 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 239, LWF discussed pre-action installations. In part 240, we will talk about recycling installations and deluge installations.
Recycling Sprinkler Installations
A recycling installation is a sprinkler system controlled by a heat detection system installed in the same area as the sprinkler heads. This type of sprinkler system is commonly found in industrial environments. A flow control valve operates when triggered by the heat detectors and after a pre-set delay, can operate again to close the water supply once the fire is under control. The valve switch becomes available for re-use straight away and can be triggered again if the fire should re-establish itself.
The authority having jurisdiction (AHJ) should be consulted prior to deciding upon which type of sprinkler system to use, as not all sprinklers are suitable for all circumstances. A recycling installation offers the benefit of reduced water damage and water waste, but there may also be drawbacks in some circumstances and careful consideration and consultation is essential.
This type of recycling installation is not the same as a wastewater recycling system for sprinklers.
Deluge Sprinkler Installations
A deluge installation is a type of sprinkler where all the sprinkler heads become operational simultaneously. The heads are of the ‘open’ type and are attached to a system of water pipework which is charged with water and attached to a deluge valve. Some smaller deluge sprinkler installations may have a multiple control.
The fire may be detected by a fire detection system or by a ‘dry pilot’ system in the risk area, where sprinkler heads are fitted to pneumatic pipework. It is normally possible for the system to be activated manually at the control valve station or other designated location.
A deluge sprinkler system is most commonly used in situations where there are oil or flammable liquid risks, gaseous risks, cooling from exposure risks and high-hazard group 4 process risks. It is usual to see deluge systems used in high-risk situations where rapid fire spread is likely.
As an aside, this type of sprinkler installation is the one most commonly seen operating in scenes of movies, where the whole building sprinklers switch on at once.
In the UK, regulations for deluge systems can be found in BS EN 12845, although NFPA 15 is also used widely in the US and other territories.
In part 241 of LWF’s series on fire engineering we will begin to look at the various components that make up a sprinkler system. 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.