Water mist systems: What you need to know
Jade Musto, Head of Suppression System Testing at the Fire Protection Association (FPA), explores the role of water mist systems in preventing and managing fire and how to be sure they are used correctly.
Water mist systems can play an important role in helping to preserve life and assets, as well as preventing the spread of fire and limiting the potential knock-on effects for communities. While not as well established as sprinklers, water mist is a promising technology that is especially effective for some fire protection scenarios.
However, these systems come with their own unique set of considerations and are the very opposite of a ‘one size fits all’ solution. So what should building owners and fire safety professionals consider when it comes to these systems?
An alternative to sprinklers
Water mist systems use very fine water sprays pushed through small holes at a relatively high pressure, quickly converting energy to steam and starving fire of the oxygen it needs to burn.
As a lower volume of water is used to put out the fire, the potential water damage is likely to be far less than would be expected from a sprinkler system. Similarly, water mist systems do not rely on the larger water supplies needed to support sprinklers.
These factors make water mist systems favourable in some scenarios. However, one of the biggest differences with sprinkler systems is that water mist systems must be designed with the exact environment in mind, which makes each installation almost entirely unique.
Where water mist works best
Water mist is particularly effective at fire suppression in enclosed environments. If, for example, protection was needed for an asset in a contained space, such as a gas turbine, fuel storage or a life safety system, a water mist installation could work well.
As water mist installations use smaller pipes and components, they take up less space than a sprinkler system so can be an appealing option for retrofit settings where installers need to be careful not to encroach on existing pipe networks.
Water mist does not work well in ventilated spaces, nor in areas where ceiling heights are above 5m. Therefore, a large open-plan office, for example, would not be a suitable setting for a water mist system. Furthermore, there are no water mist design solutions to address common issues in commercial premises, such as open areas between floors.
Therefore, while water mist systems are being increasingly used in settings such as restaurants, prisons, schools, leisure facilities and in houses of multiple occupancy, they are only suitable when these environments meet the criteria needed to host such a system.
A bespoke approach
As water mist systems are ‘project specific’, each particular hazard or occupancy requires its very own specific design. It is therefore not possible to install a new water mist system simply by referring to one of the standards available.
One of the biggest challenges for anyone considering a water mist system is that there are fewer appropriate standards or certification schemes to rely on. Plus, water mist components are bespoke to the manufacturer and are not interchangeable.
Building owners and those responsible for fire safety should therefore engage with a third party that has the knowledge and experience to carry out a thorough inspection pre-installation, as well as advise on next steps and regular maintenance. This is the only way to ensure systems will perform as intended should a fire occur.
The FPA is one of the first UKAS-accredited fire testing facilities in the UK to offer testing on residential and domestic water mist systems to BS 8458 : 2015, and is able to offer support and guidance to ensure that any installation is fit for purpose.
Even though water mist systems are particularly complex, supporting standards and certification schemes are continuing to emerge which, in time, will make their installation an easier process. Furthermore, more fire testing is being undertaken for approval of components and manufacturers are developing new products to cater for different fire scenarios.
Like other automatic fire suppression systems (AFSSs), water mist technology can be highly effective in minimising the risk of fire. With the right support, environments that would greatly benefit from a water mist system can rest assured that the technology they are using is fully fit for purpose.
For more information on the FPA’s advice and support for water mist systems, please visit: www.thefpa.co.uk/sprinkler-services/watermist-services
