The LWF Blog
Fire Safety Engineering for Design – Sprinkler Protection – Part 218
January 20, 2025 11:29 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 217, LWF looked at the potential concessions possible when sprinklers are included in the fire safety design of a building. In part 218, we talk about fire engineering using sprinkler systems.
A fire engineered design solution including a sprinkler system, designed to automatically detect and fight a fire, may mean that concessions can be made on prescriptive standards, such as compartment size, fire resistance values etc. This decision will be based on the control of the release of heat from the fire given by sprinkler activation.
Fire growth generally ceases at the time of sprinkler activation or soon after activation. This means that the time a sprinkler system takes to become operational is of considerable importance. It can be predicted, based on a wide range of variables:
- Fire growth rate
- Ambient temperature
- Sprinkler temperature rating
- Response time index of the sprinkler
- Conduction factor of the sprinkler components
- Radial distance of sprinkler from fire
- Height of sprinkler above fire
- Distance of sprinkler below ceiling height
Other factors that are of importance when calculating time taken to activate sprinklers include the type of risk, type of fuel and expected heat release rate. Gaining an understanding of the fuel load is important, and referred to in the design codes as ‘hazard’. A sprinkler system which has been designed to control a fire of 8 MW total heat output will be unable to control a fire anticipated to grow rapidly to 16 MW.
The expected/anticipated fire size, or design fire size should be determined in order to ensure the sprinkler system water discharge rates are sufficient. The design codes provide prescriptive solutions consisting of large range of hazard areas listed, along with necessary water discharge rates and expected areas of operation.
It can also be calculated, on a per situation basis, by Fire Engineers who determine the fuel load and rate of heat release of the contents and construction material of the building in question.
In part 219 of LWF’s series on fire engineering we will continue to discuss the principles of fire engineering and sprinkler systems. 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.