The LWF Blog

Fire Engineering Design and Risk Assessment – Fire Attack Time Line – Part 62

October 7, 2019 1:14 pm

In LWF’s Fire Engineering blog series for Architects and others involved in building design, we have been looking at the provisions which should be made for firefighting activities. In part 61, we showed a worked example of how the time line for a fire attack would be worked out and in part 62, we will look a little more closely at the second 20 minutes of that timeline and what must happen during those minutes.

In the theoretical timeline for fire attack, it took 20 minutes from the fire igniting to the firefighters arriving at the floor of fire origin. This indicates that the horizontal distance from the fire pump to the lift and from the staircase landing to the point at which the jet begins its work must be completed within 20 minutes.

Inside the building, the travelling time from the staircase landing to the point where the firefighters turn on their jets will be more onerous than any other stage of the timeline. The firefighters will have to run out their hoses and enter into a dangerous environment.

The time taken to carry the equipment from the fire pump outside the building to the lift inside will be undertaken in clean air and the firefighters must simply carry the necessary equipment rather than running out hose. For these reasons, even if the distances were similar, the pump to lift section of the timeline should still be able to be completed in less time than the staircase landing to fire attack section.

Where extended travel times might be called for, due to the design of the site or building, then a ratio of 3:1 should be used to work out the times available. For instance, if the available time is 20 minutes, then 5 minutes can be allocated for travel from the pump to the lift and 15 for the staircase landing to the point at which the water jet is turned on.

It is also possible to see that an extension to one section of the timeline will impact the entire timeline. Any significant changes can require an enhanced attendance from the Fire Service, or potentially, an increase in the standard of fire-resistant construction or the installation of active fire protection such as sprinkler systems.

In part 63, LWF will continue looking at the subject of firefighting. 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 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.

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