The LWF Blog
Fire Engineering Design and Risk Assessment – Sprinkler System Components – Part 27
January 4, 2018 2:42 pmIn LWF’s Fire Engineering blog series for Architects and others involved in building design, we have been discussing sprinkler systems and most recently, what components make up sprinkler systems. Part 26 looked at those items which are tested and approved by third party facilities and standard items such as pipes, fittings and stop valves. Part 27 we look at parts and practices which may go into constructing a sprinkler system and the options available.
Historically, most sprinkler systems were constructed using unprotected steel pipe. This type of pipe is suitable for use in a wet sprinkler system, although it is prone to excessive corrosion when used in an alternate wet and dry system. As mentioned in Part 26, in order to extend the life of such systems, galvanised steel pipe is an option, but in recent years, plastic pipework has become more popular.
The plastic piping itself is chlorinated polyvinyl chloride – CPVC and is used most commonly in above ground systems and in domestic and residential applications. Its light weight means installation is easier and so it has been well-received in retro-fit circumstances too. It is only likely to be suitable for light hazard installations and will be subject to certain qualifications. The CPVC itself is not flammable and is rated as self-extinguishing. Standard PVC piping has a certain resistance to fire but what makes CPVC suitable for this application is that it contains an extra 10% chlorine which allows the pipe to withstand exposure to direct flame. While the outside of the pipe may char, the inside will remain smooth and able to fulfil its intended function.
The use of welding on a sprinkler system in place should be avoided where possible. It is difficult to establish suitable quality control on site as well as increasing the risk of fire. Where welding is unavoidable, it should be carefully monitored. Pre-fabricated welding must also be subject to strict quality control with practices such as set-in sockets and ‘cut and shut’ direction changes being prohibited, due to the impact on the flow of water through the piping network.
There are various options for pipe materials and jointing methods and the choice of which is most appropriate for a given system is made based upon certain criteria:
– Material cost and availability
– Ease of installation
– Flexibility for site variances
– Experience
– Precedent
– Future maintenance requirements
So, while each situation will be judged on its own merits and using the criteria listed, the outcomes tend to lead towards a common approach within the industry.
In part 28 of this series, LWF will look at planning the installation of a sprinkler system. 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.