The LWF Blog
Fire Safety Engineering for Design – Sprinkler Commissioning – Part 257
October 20, 2025 10:32 amLWF’s Fire Safety Engineering blog series is written for Architects, building designers and others in the construction industry to highlight and promote discussion on all topics around fire engineering. In part 256, LWF talked about water provision for sprinkler systems, starting with the NFPA design guide. In part 257, we discuss the commissioning and testing of sprinkler systems.
Sprinkler systems are a piped service. In common with all other piped services, the process of installation standards, along with proper commissioning and testing of the completed installation, is very important. Unlike most other piped services, however, a sprinkler installation is not normally tested in fully-operational mode after installation. For this reason, great care must be taken with every element to ensure the design objectives are met in full.
While it is essential for the installation work to be monitored and measured, from this point we will concentrate on the commissioning and testing phase of the process.
Pneumatic and hydrostatic testing of installation pipework
The dry pipework of a sprinkler system installation should be pneumatically-tested to a pressure of 2.5 bar for not less than 24 hours. Wet pipework should be tested hydrostatically to a pressure of 15 bar or 1.5 times the working pressure (whichever is greater), for a period of at least an hour.
It is common good practice to carry out a preliminary pneumatic test prior to the hydrostatic test, which helps ensure there are no major leaks or open ends which could cause problems in the building when the system pipework is filled with water.
When using CPVC pipe and fittings, it should be noted that manufacturers of these products recommend against pneumatic testing and this must be borne in mind when choosing the most appropriate materials for the sprinkler system. The manufacturer of the pipes and fittings should be contacted in cases where there may be doubt in relation to pneumatic testing safety.
In the case of dry pipework systems, it may be prudent to prove the capability of the system to deliver water to the remote ends of the installation within a reasonable time, in response to the activation and operation of a sprinkler head.
In part 258 of LWF’s series on fire engineering we will continue discussing commissioning and testing of sprinkler systems by talking about water supply testing. 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 since 1986 to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact the LWF office 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.