ABOUT WATER MIST
Efficient use of water
Water mist is defined as water droplets that are less than 1 mm in droplet size.
Sprinkler versus water mist
Automatic sprinkler systems have set the standard for what is required to protect areas from fire. Over time, a properly dimensioned, installed and maintained sprinkler system has proven to be very effective and reliable in controlling, suppressing and extinguishing fires.
The bar for effectiveness and reliability is set, which is why most of the fire-test requirements for protecting lives and buildings with water mist are based on results obtained with sprinklers.
Sprinkler standards set requirements for a given amount of water for the areas to be protected. This makes it easy to dimension the systems, especially before people had access to digital engineering programs.
The disadvantage of defining the amount of water in a standard is that it slows down innovation and the possibilities for optimizing systems for what needs protection.
Water mist standards do not require a specific water volume, but instead require documented effective performance for controlling and suppressing fires. This requires large-scale fire tests conducted according to fire test protocols that define the type of areas the respective protocol applies to.
Designing the water mist system is based on the results from passed requirements in the fire-test protocols. Water flow and pressure, distance between nozzles and to walls, ceiling heights, etc., are described in the test reports from an ISO 17025 accredited fire lab, and in the water mist manufacturer's Design, Installation, Inspection and Maintenance (DIOM) manual.
In addition, water mist standards require component testing to ensure reliability. The test protocols for critical components such as nozzles and valves are also based on those for sprinklers.
Water mist systems that have been tested according to standards meet requirements for efficiency and reliability while being able to be optimized for the areas to be protected.
How does water mist work?
Water from corrosion-free pipe systems is “atomized” as it passes through a water mist nozzle. With many smaller droplets, a larger total surface area is created per liter of water.
The smaller droplets absorb the heat from the fire quickly and lower the temperature. The fine droplets in and around the fire boil into steam, which is an inert gas. The conversion from water to steam increases the volume of the water dramatically, up to almost 1700 times. The steam displaces the oxygen locally and “suffocates” the fire.
The droplets that do not convert to steam will wet the fire area and prevent it from spreading.
All three sides of the fire triangle are attacked – Temperature, Oxygen and Fire Load.
Advantages of low-pressure water mist
A more efficient use of water has its obvious advantages;
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A smaller water requirement means a smaller water intake or water tank
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Smaller dimensions of pipes and fittings
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Easier and faster installation
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Discreet and space-saving design with corrosion-free materials
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Low maintenance costs due to requirements for corrosion-free quality of all components
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Non-toxic extinguishing medium
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Less water damage and shorter downtime in the event of a fire
In addition, smaller dimensions mean a significant reduction in greenhouse gas emissions compared to traditional sprinkler systems built with steel pipes.
Multiconsult prepared a greenhouse gas report where they compared the use of our water mist system with traditional sprinklers for a hospital.
The conclusion is 71% reduced CO₂ emissions for the products alone, 72% reduction on materials! The report does not include transport, storage, installation work (HSE), etc.
Read Multiconsult's report here.
Frequently asked questions
Similar to sprinklers, there is no FG approval for the system. Our low-pressure water mist systems are designed, installed and inspected by FG approved companies, according to TEK 17 and applicable standards.
We supply LPCB certified nozzles, and the components included in the systems are the same certified components used in sprinkler systems, as these are approved for the same pressure class. We set higher requirements for pipes and fittings as these must be corrosion-free, in addition to being approved for use in automatic suppression systems.
Note FG guidance for water mist systems is currently being revised to include reference to the Norwegian and European water mist standard NS-EN 14972-1. The standard meets requirements for efficiency and reliability.
Yes, of course!
The water mist standard include the protection of Residential occupancies – NS- EN 14972-1.
VIDEO
Water mist and spray pattern
This video shows the spray pattern of water mist and sprinklers in a parking garage with a ceiling height of 3 meters.
First, you see water mist as fire tested with 8.4 bar pressure. Then the front right nozzle is replaced with a K80 sprinkler head with 1 bar pressure, before the pressure is increased to 4 bar.
See what happens to the droplet size!
Low pressure water mist fire suppression system
This video shows different fire scenarios with large and small fire loads with low-pressure water mist - diesel fires, barn fires, residential fires and exterior facade fires.