The LWF Blog

Fire Engineering Design and Risk Assessment – Sprinkler System Installations – Part 23

November 30, 2017 12:12 pm

In this fire engineering blog series by LWF for Architects and professionals involved in building design and construction, we have been covering sprinkler installations and their impact on a fire safe design. In part 22, the thermal sensitivity of sprinkler heads was discussed and in Part 23, the various types of sprinkler system will be introduced.


Each building will have its own requirements and capabilities when it comes to the installation of a sprinkler system. Each project can have differences in water supply, supply control and alarm system and so the sprinkler system must be the one which is most appropriate for the circumstances. The variation in parameters has meant that different types of sprinkler system have been developed to serve those needs.


One common part of a sprinkler system installation, no matter the design, is the inclusion of a valve(s) to isolate the system from the water supply. The valve can be used by the Fire Service when the fire is under control or by appropriate maintenance personnel for system checks, repairs or alterations. In a larger system, the valves can be engineered in such a way that only a part of the system is shut down at once.


Some systems operate in ‘dry’ mode, meaning that the water to operate the sprinkler system does not sit in the pipes leading to the sprinkler heads, but is delivered to the pipes in the event of fire. A fire engineered solution will take into account pipe size and the time taken to deliver water to the sprinkler heads, because the fire size cannot be controlled or reduced until the water arrives and sprinkler effectiveness can be affected by an excessive waiting period.


For this reason, the most commonly installed sprinkler system is a ‘Wet Installation’. When used appropriately, a wet installation sprinkler system is the simplest and most effective sprinkler available. The pipework for the system is constantly charged with water, ready to operate at its operational pressure. This means that in case of a fire, this sprinkler system has a very quick reaction time.


The main reason this type of system is not universally used is that, due to the water held in the pipework, it is not suitable for extremes in ambient temperature. The water in the pipes cannot be allowed to freeze, nor must it be heated beyond 70°C.


In Part 24 of this series, we’ll look at what type of system is recommended for environments where it may be excessively cold during the Winter months, but normal during the warmer weather. 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 for over 25 years to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact Peter Gyere on 020 8668 8663.


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.


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