The LWF Blog

Fire Engineering Design and Risk Assessment – Sprinkler Installation Design – Part 38

March 20, 2018 11:39 am

In LWF’s fire engineering blog series for architects and others in the building design business, we have recently been looking at the design of sprinkler system installations. In part 37, the importance of a providing a sufficiently reliable water supply was discussed. In part 38, we talk about the need to ensure design objectives are met through thorough commissioning and testing of the completed installation.


Unlike the majority of other piped installations, a sprinkler system is not usually tested in full operational mode after installation, because its job is to react to and subdue a fire – a situation which is not welcomed. Periodic testing to simulate a fire can be undertaken, however, this is not considered to be a full, ‘life-like’ test. Due to the lack of a full test after installation, it is important that the design objectives are fully met and the installation is monitored carefully.


The possible commissioning and testing of a new sprinkler installation fall under four headings, as follows:


 Pneumatic and hydrostatic testing of installation pipework

 Water supply testing

 Alarms and monitoring facilities

 Third-party certification


An overview will be given of each area of testing.


Dry pipework should be tested pneumatically for 24 hours to a pressure of 2.5 bar. Wet pipework is tested hydrostatically for at least an hour, to a pressure of 15 bar or 1.5 times the working pressure – whichever is greater.


Pneumatic and hydrostatic testing of installation pipework


Before wet pipework becomes ‘wet’ (i.e. Filled with water) it can also be tested pneumatically as this helps ensure there are no leaks or open ends. However, CPVC pipe manufacturers do not recommend this course of action for their products and this consideration should be made at the time of deciding on materials for the system. Manufacturers can be consulted with regards to the safety of undertaking pneumatic testing on their products, where there is doubt.


Where a sprinkler installation will be dry, it is prudent, where possible, to test the ability of the system to deliver water to the most remote area of the system within a reasonable time in response to a sprinkler head operating.


Water supply testing


Water supply testing consists of checking the capability of the water supply through the complete range of its design requirements in order to test performance. To achieve this, flow measuring devices should be provided at the installation control valves and adjacent to pumps in order that water flow and pressure can be measured. Where diesel pump sets are used, tests should be completed to check the unit starts automatically as required.


In part 39 of this series, the tests which should be undertaken on a new sprinkler installation in terms of alarms and monitoring and third-party certification will be overviewed. 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.



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