The LWF Blog
Fire Safety Engineering for Design – Sprinkler Heads – Part 230
April 14, 2025 10:12 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 229, LWF discussed sprinkler heads, particularly the five key attributes of a sprinkler head that are important to sprinkler design. In part 230, we look at conventional and spray types of modern sprinklers, before discussing quick response sprinklers.
Conventional and spray sprinklers are very commonly seen in installations around the world. They are designed to be suitable for most situations and are usually either mounted onto pipes or sit below a suspended ceiling. Miniature types are available and are the most popular choice as they are less obtrusive than the full-size counterparts and not so damaging to the aesthetic.
The differences between a conventional and spray sprinkler system are minimal. A conventional sprinkler directs the spray both upwards and downwards in approximately equal proportion. This allows for a significant amount of ceiling wetting, and direct distribution below.
A spray sprinkler system is designed to direct its spray downwards for the most part, they are designed for either pendent or upright orientation, although some are designed to be fitted either way and are known as ‘universal’.
Quick response sprinklers are those which have an RTI of 50 (metre-seconds) ½ or less. The quick response nametag refers to the entirety of the sprinkler, including spacing, density and location, not just the fast-respond release element.
The main difference between quick response sprinkler and standard response sprinkler heads is thermal sensitivity. Quick response sprinkler heads activate slightly faster than a standard response head. This is due to differences in the glass bulb. The standard response sprinkler will have a 5 mm glass bulb, but a quick response version will have a 3 mm glass bulb. The bulb’s smaller size speeds up thermal responsiveness.
Differences between the two types of system also exist in terms of spacing, density and placement of sprinkler.
Quick response sprinklers are required in all new systems installed in light-hazard occupancies and have been since 1996.
In part 231 of LWF’s series on fire engineering we will continue our journey through the types of sprinkler, beginning with Sidewall Sprinklers. 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.