The LWF Blog
Fire Safety Engineering for Design – Sprinkler Protection – Part 215
December 23, 2024 9:08 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 214, LWF talked about sprinkler system protection and reliability. In part 215, we continue to discuss sprinkler systems reliability, including why less than 100% effective can still be acceptable in terms of fire safety.
While sprinkler systems cannot claim to be 100% effective, any claims that they should not be used in trade-offs with other fire protection measures for this reason are flawed, as it assumes other fire protection measures are 100% effective. The overall efficacy of an appropriately installed and maintained sprinkler system is extremely high.
All fire protection measures can fail, given inappropriate conditions or usage. For instance, fire doors may fail to prevent the spread of fire or smoke due to being left open or because they were poorly fitted.
The fire safety design for a building should balance passive and active fire protection measures to fulfil the needs identified in the most suitable and economical way.
The reliability of sprinkler systems was compared to passive fire protection measures in PD 7974-7 Application of fire safety engineering principles to the design of buildings – Probabilistic risk assessment. It shows probability figures of between 0.75 and 0.95 for successful sprinkler activation (although it’s likely a correctly installed and maintained system will be at the higher end of the figures). This compares favourably with passive fire protection system figures from the British Automatic Fire Sprinkler Association’s Sprinklers for Safety which includes the following probabilities:
Probability of fire door being wedged open 0.3
Probability of self-closing doors failing to close when needed 0.2
Probability that fire-resisting structures will achieve at least 75% of the designated fire resistance standard – 0.25 for suspended ceilings, 0.65 for partition walls
While there are a great many advantages to installing a sprinkler system where usage is appropriate, the positives outlined in LWFs blogs are generalised and each situation, proposed building and site should be assessed fully and fire protection designed appropriately. A ‘one size fits all’ solution would never be appropriate. Consultation with a fire engineer at the design stage is important.
In part 216 of LWF’s series on fire engineering we will review the benefits of 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.