Water Mist Standards

Water mist offers several advantages over conventional sprinkler technology in some applications

WATER MIST STANDARDS

Since 2000 there has been an increasing interest in the application of high pressure water mist technology in fire protection systems. Water mist offers several advantages over conventional sprinkler technology in some applications.

However there are significant issues in respect of the utilisation of standards as, unlike sprinkler systems, water mist systems are “project specific” and each particular hazard or occupancy requires its own very specific design. It is therefore not possible to design a mist system simply by reference to one of the standards available – unlike sprinkler systems where, for example, reference to BS EN 12845 or BS 9251 enables a full design to be produced and a fully compliant system to be installed. So while BS 8489 Part 1 sets out the design criteria for a water mist system, its suitability for a particular fire risk is dependant on there being an acceptable test protocol. This may be found in Parts 4-7. If it is not, then a specific protocol will have to be developed for the proposed use.

British Standards for Watermist

BS 8458:2015 Fixed fire protection systems. Residential and domestic watermist systems. Code of practice for design and installation

BS 8489-1 2016 Fixed fire protection systems. Industrial and commercial watermist systems. Part 1: Code of practice for design and installation

The BS 8489 series includes the following standards:

BS 8489-4 Fixed fire protection systems. Industrial and commercial watermist systems. Fire performance tests and requirements for watermist systems for local applications involving flammable liquid fires

BS 8489-5 Fixed fire protection systems. Industrial and commercial watermist systems. Fire performance tests and requirements for watermist systems for the protection of combustion turbines and machinery spaces with volumes up to and including 80 m³

BS 8489-6 Fixed fire protection systems. Industrial and commercial watermist systems. Fire performance tests and requirements for watermist systems for the protection of industrial oil cookers

BS 8489-7 Fixed fire protection systems. Industrial and commercial watermist systems. Tests and requirements for watermist systems for the protection of low hazard occupancies

There is another type of system which utilises watermist technology and which is now effectively regulated through a BRE standard and that is the Personal Protection System. These are free standing, self contained units which can protect the occupant of a bedroom. LPS 1655, which fills a gap in fire standards given the absence of a dedicated BS or EN standard, sets a minimum, credible performance level for PPS to instil confidence in specifiers and users. It is likely that BS committee FSH/18/5 will commence work on a new standard which will supplement LPS 1655 and also set the criteria for the use of PPS and the capabilities of those who specify and install these.

EN Standards

At present, the only EN document covering the design and installation of watermist is a Technical Specification: EN TS 14972:2006 Fixed firefighting systems — Watermist systems — Design and installation.

This document, which has never been widely used in the UK, is presently being revised by CEN TC191/WG10 and is expected to be reissued in 2017 as a draft EN standard for the design, installation and maintenance of water mist systems. To complement it a series of component standards are being developed, as are a series of application standards, for example for industrial oil cookers. As and when these documents are published it will trigger the removal of all or part of the BS 8489 series. It is unlikely that BS 8458 will be affected as there appears to be no CEN interest in watermist systems for residential premises.