WaterMist systems

 We have been asked on many occasions if water mist systems can be used to comply with DD251:2000. In short, whilst we believe there may be potential for these systems, there are several technical problems that need to be resolved before these systems would be suitable for domestic/residential use.

In particular we do not believe they currently comply with DD251 for a number of reasons including the following :- 

1.      DD251:2000 requires a delivery of 60 l/min over an area of 15 sq. meters. This equates to a density of 4 mm/min. The rest of the world accepts a minimum density of 2.02 mm/min. under NFPA and UL standards.

Water mist systems (as are currently being marketed for domestic use) deliver considerably less water than 2.02 mm/min.

2.      DD251:2000 requires a delivery of water for a minimum of 10 minutes in a single family property and 30 minutes in a multi-family property.

Water mist systems (as are currently being marketed for domestic use) only deliver water for a maximum of 4 minutes – if that.

3.      DD251:2000 requires a delivery of a significant amount of water onto the walls of the compartment at high level to aid cooling of the compartment.

Water mist systems (as are currently being marketed for domestic use) provide no wall wetting.

4.      DD251:2000 requires the system to deal with a wide variety of fires in a wide variety of locations within the property

Water mist systems (as are currently being marketed for domestic use) are risk specific and not versatile.

5.      DD251:2000 requires the systems to be installed to a known specification using products independently tested to acknowledged international standards.

Water mist systems (as are currently being marketed for domestic use) have no published specification or independent test data available.

6.      DD251:2000 requires the systems be installed by an experienced sprinkler contractor who is suitably qualified and experienced and has independent documentation providing evidence of this.

Water mist systems (as are currently being marketed for domestic use) have no training or certification schemes in place at this time.

7.      DD251:2000 requires that only components that have been tested and approved to internationally recognised standards - such as British Standards DD252 or Underwriters Laboratories UL1626 be used.

There is currently no published specification for the water mist systems (as are currently being marketed for domestic use) and no approvals of the components used in those systems, to be used in domestic/residential properties.

 For these reasons, and others, we do not believe that at this time water mist systems can be used to comply with the requirements of the British Standard DD251:2000.

It may be that with further development together with independent testing and product approvals, water mist systems will have a part to play in domestic/residential fire safety. However, until they have been proven to work in domestic/residential scenarios, their use as a compensatory factor for Building Regulation requirements leaves those specifying these systems (such as Fire Service personnel and Building Control officers) open to personal liability should the system fail.

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