The LWF Blog

Fire Engineering Design and Risk Assessment – Firefighting & Rising Water Mains – Part 38

April 29, 2019 1:34 pm

In LWF’s fire engineering blog series for architects and others in the building design business, we have been talking about firefighting and rising water mains in buildings. In part 37, we looked at the parameters to be considered when deciding where internal mains and landing valves should be located in a building with a rising main. Part 38 will continue from that point.


While the main recommendations given in guidance documents Approved Document B and NFPA 1 for landing valves has similarities, there are some significant differences, as indicated in the previous blog.


However, NFPA 1 concurs with Approved Document B in reference to sprinklered and non-sprinklered buildings, with NFPA 1 recommending that in the case of class I and class III systems, a sprinklered storey should have a fire main outlet within 61 m of even the most remote portion of the floor and that in a non-sprinklered storey, each area must be within 45.7 m.


In the case of class II systems, NFPA 1 states that all portions of each floor level of the building should be within 39.7 m or 36.6 m of a landing valve, with the difference being dependent upon the size of the hose connections.


BS 9999 provides recommendations most like those given in Approved Document B, but also resembles the advice given in NFPA 1 with the following:


“It is not necessary for lobbies to be provided to escape stairs solely to accommodate dry riser outlets. The riser outlets may be sited on landings or half-landings on the stair, provided that sufficient space is available for their use by firefighters without obstructing the opening of doors.”


NFPA 1 and Approved Document B exhibit clear differences between the guidance given on the placement of landing valves and the maximum allowed hose run distances from the landing valves for firefighting purposes. One of the most significant differences relates to APB’s direction on whether or not the landing valve is situated in a firefighting shaft or protected stairway, or whether or not a building is sprinklered. In comparison, the NFPA 1 method is that landing valves should be located at each intermediate landing between floor levels in every required exit stairway. NFPA 1 also recommends more landing valves than Approved Document B.


When considering which suggestion is optimal, the practical ramifications must be considered and to that end, in part 39 of this series, we will look at the Fire Service standard operating procedures in the UK and discuss the physiological limits of firefighters. In the meantime, if you would like to discuss this blog series or your own project, please don’t hesitate to 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 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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