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6.8.4 Mains Water Supplies

As per our Design, Installation and Operation Manual (DIOM):

We state as a precondition that the cold-water supply for the system must deliver 8 litres per minute flow at a minimum of 1.5 bar (150kPa) and a maximum of 16 bar (1.6 MPa) static pressure. In case the pressure or flow is too low, a priority valve or a booster pump must be used to provide the required flow and pressure. The pump requires only 5.6 lpm and 1 bar pressure, so the safety margin is embedded in this requirement. The minimum guaranteed UK Supply by the Office of Water Services (OFWAT) is 9 lpm, and the typical flow between 10 - 25 lpm. As Automist does not require more water than expected by a typical household appliance, and therefore, you are not required to inform the water undertaker. Additional measures can be considered to improve resilience further in a shared, boosted water supply.


Water flow pre-installation test:

Automist water flow pre-installation test


Water pressure pre-installation test:

Automist water pressure pre-installation test


Automist Smartscan Hydra uses electronic actuation and advanced sensor technology to ensure that only the spray head with the best access to the fire is activated. That means that the pump will never be asked to serve more heads than it's designed to work with.

Competing sprinklers, by contrast, are triggered by a more basic mechanism. This means that any spray head near a fire will activate, even if the system can't cope with that many heads running at once. Some manufacturers have tested their system in larger rooms, but according to section 6.6.1 of BS 8458, even those can't be used in rooms over 32m2, unless they are specifically designed to cope with three or more heads activating at once. Even rooms below 28m2 can fall foul of this problem if their width is above 5.1m.

A short extract from BS 8458, the standard for watermist sprinklers:


Quote from BS 8458 on water supply


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