Water Mist Fire Suppression Systems
The increased use of automatic fire suppression systems in the residential sector is driving developments of new systems in a quest to replace sprinklers. But this is a tall order, as sprinklers are very-well proven and the latest designs are low cost, use less water and are concealed from view.
Here is a quick technical overview of a Mist Systems with some comparisons to Sprinklers.
For a more-detailed commentary on mist click here – Are mist systems Fit-for-Purpose in homes
Here are 2 video showing a sprinkler system and a mist system in operation
A Water Mist System: After 5 mins the fire brigade step in to fully quench the fire
Sprinkler System: 60 seconds and the fire is out.
The Technology comparison
There are essentially 2 types of Mist System: Low pressure Mist and High Pressure Mist
Low pressure mist systems:
Have many similarities to sprinkler systems – they use very similar infrastructure, but the heads are different (mist heads emit finer water droplets) and operate at 6 bar upwards to around 12 – 15 Bar. Whilst these are low pressure mist heads, they still work at a much higher pressure than sprinkler heads and more than most water mains can supply, so a pressure pump is always needed to operate the system. Interestingly, the specifications and tests show that mist heads require more water to operate than an equivalent low-flow sprinkler system. There is no fully concealed version of mist head at present so possibly not as aesthetically pleasing as a concealed sprinkler head. These ‘low pressure’ mist heads are more costly than sprinkler heads so the systems will generally be more costly to install.
High pressure mist systems:
Use very high pressure water pumps and pipework which is fed around the fabric of a building to the mist heads. High pressure mist operate at anything up to 100+ bar. Less water is used because the mist is very fine – similar to a fog – and shoots from the head at high pressure towards the fire. Coverage of each head is limited so careful design and head positioning is necessary to ensure all areas are protected. Because of the high pressures, coverage of larger buildings requires multiple systems or additional booster pumps – this pushes up the complexity and cost. Indeed, for a block of flats, a self-contained system per flat would likely be necessary.
For more information go to Are mist systems Fit-for-Purpose in homes