CEO, Assured Fire & Security

Author Bio ▼

I have grown Assured from a start up company to a nationwide and international business, my business knowledge has come mostly from hands on experience in running a fast paced and dynamic SME, building a team of highly motivated and ambitious people has always been a high priority in order to serve my highest priority which is to provide great customer service for our clients. At Assured we are proud of our people and how we interact with our clients and suppliers, our USP is our people and how they treat our customers, nothing is hidden and you can always be Assured of a quick and honest approach to your requirement.
January 28, 2016

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Water-Mist Fire Protection: a Guide for the Responsible Person

The recent rise in the interest and use of water mist fire suppression systems in the UK is due to the many advantages over other fire suppression systems.

The advantages of water mist include:

  • No chemicals used
  • No risk of asphyxiation as with gas fire suppression
  • Less damage to property than sprinklers and easier to clean up
  • Environmentally friendly

So what is water mist?

A water mist system is a fixed fire protection system that discharges a fine spray of small water droplets. Water mist systems propel water through a specially designed nozzle, breaking the water up into hundreds of micro droplets which produce the mist.

In the event of a fire, the water droplets will the remove heat and displace oxygen from the affected area, resulting in the fire being extinguished.  The mist lowers the temperature, lessens the radiated heat and reduces the oxygen concentration to the extent that combustion can no longer be maintained.

Sprinkler Systems Vs Water Mist Systems

So what are the differences between sprinkler systems and water mist suppression systems?

  • Water mist systems discharge less water than sprinkler systems.
  • Because less water is used, clean up and damage to property is less with water mist suppression
  • The average water mist droplet has a total surface area at least 100 times greater than the volume of water from a sprinkler system, meaning more effective suppression.

Due to the large volumes of water required with sprinklers then a large tank or even pumphouse as is required whereas cylinders or small standalone tanks can be used for water mist.

  • Water mist enables ‘smoke washing’, whereby the smoke particles attach to the droplets and fall to the floor, eliminating the spread of smoke throughout the building.
  • However, water mist suppression is more effective in compartmentalised situations and may not be suitable for larger areas.
  • Water mist droplets can be blown away under certain conditions such as air conditioning and open doors reducing effectiveness.

The major difference however, is that sprinkler systems have standards and approvals for both the components of the system and the design and installation. At the moment, water mist suppression systems don’t.

Current Standards

Currently there is no published British Standard for water mist systems or the components.

Existing water mist standards such as the National Fire Protection Association (NFPA) 750 Standard on Water Mist Fire Protection Systems or International Maritime Organisation (IMO) Standards are not directly applicable to UK land-based applications. A European water mist technical specification (CEN TS 14972) has been published but has not been adopted in the UK as its suitability for UK application is uncertain.

However, two new Drafts for Development have been issued:

  • DD 8489: Fixed fire protection systems – Industrial and commercial water mist systems
  • DD 8458: Fixed fire protection systems – Residential and domestic water mist systems

These haven’t been published as full British Standards as there is currently insufficient technical data to support them. These documents try to define the testing protocols for water mist systems in various different applications, but as yet they don’t cover all water mist scenarios. Tests for further applications should be developed going forward and published in additional sections.

Should you Choose Water Mist Fire Suppression?

In the absence of a generalised design and installation standard, the suitability of water mist fire suppression for your building depends on a number of factors such as room size, ventilation and insurer’s requirements.

Water mist systems should be considered on a case-by-case basis to determine whether a proposed system will meet the fire protection objectives, which need to be clearly stated by the supplier.

Assured Fire & Security are experts in all types of fire suppression, and can design and install systems suitable for your business. For more information please contact our friendly team on 0845 402 3045 or alternatively download our Free Fire Suppression Buyers’ Guide.

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4 Comments on "Water-Mist Fire Protection: a Guide for the Responsible Person"

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alanbrinson
Guest

Simon, BS 8458 was published on 30 November last year and is available on the BSI web site.

Assured
Guest

alanbrinson So it has! Thank you for the update.

Kylie Dotts
Guest

I didn’t realize that water mist could help reduce temperature and help move air to other areas. It would make sense that a secondary benefit would also be moistening the fuel that the fire is burning which would probably make it harder to burn. I think that it’s really important to be prepared for any situation but especially ones, like a fire, that could cause serious damage to your property.

Dave Anderson
Guest

That is really interesting that mist systems use less water than sprinklers. Something that I would like to do is have a test of which will put out a fire more effectively. Either way, I think it would be good to have some sort of system for fire protection.