The LWF Blog
Fire Safety Engineering for Design – Sprinkler Heads – Part 234
May 12, 2025 10:43 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 233, LWF talked about concealed pattern sprinklers and concerns over slower sprinkler reaction time. In part 234, we will discuss other devices/sprinkler systems for particular uses.
Multiple controls
When using open sprinkler heads or sprayers, multiple controls consist of valves in the closed position by default with a heat-sensitive device, once triggered, they open to feed one or more sprinkler heads or sprayers.
Medium-velocity sprayers
For systems designed to control fires involving combustible liquids and gases with low flashpoints, medium-velocity sprayers produce directional fine droplet spray to douse the flames and cool the surfaces of vessels.
High-velocity sprayers
Consist of sprayers with open nozzles and which produce a directional spray of large droplets, designed to extinguish combustible liquid fires that have higher flashpoints.
Dry pendent sprinklers
Designed for use in dry, alternate wet and dry or pre-action systems, where water cannot be held in the drop pipe to the sprinkler head due to conditions, e.g. the water may freeze due to low temperatures. They take the form of a downward pipe with a valve at one end and the sprinkler head at the other. When the sprinkler head activates, the valve at the top opens and allows water to pass down the pipe to the sprinkler head outlet.
Dry upright sprinklers
Similar operationally to dry pendent sprinklers but less commonly used.
Window Drenchers
Typically used as a method of fire resistance for glazing, window drenchers spray water onto glazing to cool them in a fire situation. These are commonly used where separation from neighbouring buildings on fire may be an issue. Unlike other types of sprinkler, window drenchers work on the external face of a building and are often positioned on roofs and over windows with or without openings. All nozzles in a drencher system are designed to activate simultaneously, rather than on an individual basis as with a sprinkler system.
In part 235 of LWF’s series on fire engineering we will give an overview of the thermal sensitivity of sprinkler heads. 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.