The LWF Blog

Fire Engineering Design and Risk Assessment – Fire Suppression & Sprinklers – Part 3

July 12, 2017 9:12 am

In this Fire Engineering Design and Risk Assessment blog series for Architects and others involved in building design, we have been discussing how fire suppression is designed and sprinklers are used to suppress fire. In Part 2, we looked at an example of a ‘zero damage’ system, which involved multiple methods of fire warning and suppression to ensure no fire damage was incurred.


While a ‘zero damage’ system is a very unusual system and not one likely to be found in general use, the use of sprinkler protection is commonplace and Part 3 of this series will give an overview of how they work.


While sprinklers tend to be thought of as fairly new innovations, in fact they have been in use in some form or another since the 1800s. The first identified fixed sprinkler system was in use in the Drury Lane Theatre in London as early as 1812.


The first systems designed and used were based simply on sparge pipes, which are horizontal pipes with holes drilled into them. The water was then manually sent down the pipes to distribute it over any fire that occurred. The next stage of innovation was systems attached to a pressurised water pipework system, which allowed more water to be delivered at a faster rate.


As techniques in engineering and materials progressed, further developments in terms of thermal response and system appearance allowed sprinkler systems to largely become the systems we see today. They are still based on the original idea of a water pipe being stoppered by a valve with a heat-sensitive element.


Sprinklers should be used mainly for Class A fires. Class A Fires involve combustibles such as wood, paper, trash or anything else that leaves ash after burning. Water works best to extinguish a Class A fire. The use of sprinklers on other types of fire would have to be considered as part of the overall fire risk assessment of a building and set of circumstances.


While the movies might show whole buildings being drenched as the sprinklers activate because of a small fire or because someone set off a fire alarm, that is almost never the case. A sprinkler system comprises pipes and heat-sensitive valves enclosed in the sprinkler heads. When a fire is detected by an individual sprinkler head, the valve opens and water is released in the form of a spray to the heart of the fire. If the fire is widespread enough, other sprinklers in that area may become active too.


As the alarm is raised as soon as the sprinkler becomes active, the sprinkler system remains active until the arrival of the Fire Service, either suppressing the flames until it can be put out or extinguishing it altogether in many cases.


In the next fire engineering and risk assessment blog, we will continue looking at Fire Suppression. 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.


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