The LWF Blog

Fire Engineering Design and Risk Assessment – Fire Attack Time Line – Part 60

September 23, 2019 12:47 pm

In LWF’s Fire Engineering blog series for Architects and others working in building design and construction, we have been discussing firefighting from a fire engineering point of view. In part 59, we looked at planning fire service access for large single-storey buildings. In part 60, the fire attack time line will be reviewed.

The strategic planning of a fire attack by the Fire Service should be undertaken bearing in mind the fire service resources available and by identifying the fire risk areas in a building, as follows:

– Establish the speed and weight of Fire Service attendance
– Calculate the likely/potential size of a fire by the time firefighting activity begins
– Identify the fire risk areas
– Plot the fire attack zones on a map using fire-resistant walls and doors or by assessing fire development rates in general floor areas
– Pinpoint locations for stopping jets
– Decide internal ‘fire safe’ access routes
– Calculate travel time within buildings for firefighting attack
– Identify ideal entry points, locations for hard-standing and fire hydrants
– Establish arrival protocol and entry preparation time

The process described should allow a time line to be developed.

The theory may be easier to understand when laid out as a worked example. Let’s state that we are working on a high-rise building which has four firefighting shafts to allow every part of every storey to be within 50 metres of the fire-resisting doors giving access to a compartment, from a staircase where there are landing valves.

– Establish speed/weight of Fire Service attendance

The nearest fire stations and methods of staffing would allow four pump crews to arrive at the fire attack access door/s within 10 minutes of the call for assistance. Any additional fire pumps could take up to 30 minutes to arrive. It must be noted that Fire Service attendance times are not guaranteed, this is provided for indicative guidance only.

– Potential size of fire

The type of occupancy and fire compartmentation means that any fire should be contained within a compartment or sub-compartment and will be limited in size enough that it can be controlled by two jets for a period of 120 minutes. For firefighting attack, if we assume a safety factor of 3, that would give an assessed time from discovery to turning on the first jet of 40 minutes.

In part 61 of this series, we will continue working our way through the example of how to establish a fire attack timeline. 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 LWF on freephone 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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