The LWF Blog
Fire Safety Engineering for Design – Water Mist Systems – Part 293
June 29, 2026 8:37 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 292, LWF began to look at water mist systems by detailing the relevant standards. In part 293, we discuss the scope of the standards in relation to water mist systems.
The last blog contained standards pertaining to land-based applications. Marine systems have different standards and so any water mist system suitable for marine use should not be considered suitable to meet the test requirements of land applications.
The standards for land-based applications establish the framework for the design objectives, installation requirements, commissioning procedures, inspection regimes and maintenance obligations associated with water mist fire suppression systems. However, they are not system design manuals, they are created to define the performance criteria and procedural elements needed to ensure a water mist system is installed and maintained in a manner consistent with its approved fire-test evidence and intended application.
Unlike traditional sprinkler systems, which benefit from extensive prescriptive design rules, water mist systems are largely performance-based. Therefore, the detailed design of a water mist installation relies upon the specific manufacturer’s technology, including aspects such as nozzle characteristics, operating pressures, droplet size distribution, discharge density and system configuration.
The suitability of any proposed system must be demonstrated through full-scale fire testing conducted in accordance with recognised test protocols (applicable to the hazard being protected). The components from different manufacturers do not tend to be interchangeable and the design methodologies will differ. Third-party certification and approval of the system and components is essential to demonstrate compliance and reliability.
To assist with the complexities of water mist technology, the Fire Protection Association (FPA) through RISCAuthority developed a series of structured questionnaires intended to assist relevant parties and end users in assessing water mist system suitability:
Water mist questionnaire: Building compartment protection – Deluge open-head systems (IQ1)
Water mist questionnaire: Building compartment protection – Local application protection (IQ2)
Water mist questionnaire: Building compartment protection – Systems incorporating thermally-actuated closed heads (IQ3)
The FPA questionnaires can be found on the FPA website
In part 294 of LWF’s series on fire engineering we will begin to discuss the properties of water mist. 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.