Watermist: A fire engineers view
Watermist systems installed in buildings can reduce the fire risk to life. It can also significantly reduce the degree of damage caused by fire and provide property protection.
Watermist fire suppression systems have demonstrated their value in assisting the protection of life and property in industrial and commercial applications for many years. A mist system operates at an earlier stage in the development of a fire when compared to sprinklers, and in many cases are more practical to install, especially in small buildings. Sprinklers can also cause significant water damage when activated, which is minimised when compared to mist.
In my opinion, with the recognition that the largest number of fire related deaths occur in the home, the introduction of a standardised domestic watermist fire suppression systems marks a significant move in the right direction for the fire safety industry.
British Standard (BSI standard “BS 8458:2001) compliant watermist systems protection can be used in order to reduce the fire risk, and as a compensatory feature where the provisions of fire safety guidance are deviated from in some way.
For example, where a new habitable storey is to be added by converting the loft, and/or creating “open plan” at ground floor, the provisions for escape need to be considered throughout the full extent of the escape route. In many cases, to be compliant with the guidance, a stairway needs to be fire protected to provide safe escape route for occupants from upper floors. Alternatively, it may be possible to provide mist protection to the open-plan area, in conjunction with fire-resisting partition; fire curtain, fire doors or additional ventilation equipment. This will allow the occupants of the loft room to access an escape window at first floor level in the event of a fire in the open-plan area. There may also be cases where this partition can be avoided and a bespoke fire engineered solution can be developed negating this requirement. This is subject to a case by case assessment of the project by a qualified fire engineer and the associated risk assessment followed by building control approval of the strategy.
Therefore, as part of the overall fire strategy for a project, a mist system can be a valuable asset with benefits of reduced risk to life safety, design flexibility and non-invasive installation. From a fire engineering standpoint, I believe the move towards mist systems to be a highly positive one. While sprinklers may still be appropriate for larger buildings and property protection applications, mist systems appear to be a better fit for small or domestic developments.
By Paul Yeomans Fire Engineer / Director at Fire-Q (https://www.fire-q.co.uk/)