The LWF Blog
Fire Engineering Design and Risk Assessment – Firefighting & External Water Supplies – Part 25
January 30, 2019 12:22 pmIn LWF’s fire engineering blog series for Architects and others in the building design industry, we have been discussing firefighting and most recently, those elements which must be planned to aid the Fire Service if they arrive to attend a fire at the premises. In part 24, we began to look at how the advice given on placement of hydrants varies from guidance to guidance and how to interpret and rationalise the data given practical requirements. In part 25, we will continue from that point.
When deciding the minimum distance a fire hydrant should be from a protected building, the most important consideration is that it be beyond the reach of flames and smoke if there are openings, like windows or a shop front and that it be safely positioned in case of a full or partial collapse of the structure.
In cases where it is essential that water hydrants are placed down a roadway (which could be found in a shopping centre, an industrial estate etc.) the hydrants should be placed at the junctions of roadways. Where the hydrants must be placed on a roadway between buildings, they should alternate sides of the road to maintain maximum distance requirements from buildings on each side of the road. This arrangement should also avoid the necessity to obstruct the road with hose lines more than is necessary.
Where hydrants are to be located on a roadway, it is preferable that each hydrant is fitted on spurs with a shut off valve near the main, which allows for repairs of individual hydrants as necessary without shutting down the whole main. This expediency then allows for a single main to be run down the centre of the roadway.
Another important consideration when placing hydrants is its proximity to an entrance door to the building which gives access to all parts of the building (or doors which give the only available access to certain areas of the building). In this scenario, the fire pump upon arrival at the scene of the fire will be able to stop within one hose length (approx. 20 m) of the building entrance or riser inlet.
This distance is generally far enough away from the building to protect the engine from the fire or building collapse, but close enough to deploy a hose line into the building quickly. (The assumed speed of running a hose from a pump is 2 m/sec and in this instance of approx. 20 m, the time taken would be 10 seconds). Where fire compartment walls are in place near the access doors to be used, the fire appliance may be able to position much closer to the access point safely.
In part 26 of this series, LWF will continue to look at the positioning of hydrants. 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.
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.