A droplet from a typical fire sprinkler will have a diameter around 1mm
Sprinkler systems are manufactured, designed, installed and maintained within a quality regime that ensures they have the highest probability of correct function of any suppression technology. These systems have an ability to perform when required and to prevent false operation when not.
A relatively new type of fire suppression, a water mist system is a fixed fire protection system, comprising components for automatic detection and actuation, water supply delivery and water automisation. Water mist nozzles release a very fine spray of water droplets that fill a compartment with a mist. These systems are distinctly different and are not standardised, unlike automatic sprinkler systems.
Project specific, water mist systems are suited to situations where ceiling heights are low, enclosure volumes are small, fire sizes are large, and the compartment is well sealed. Sprinkler systems are not similarly constrained.
Requirements for, and references to, sprinkler systems within UK Building Design and Fire Engineering codes are specific to sprinkler technology. No relevant ‘equivalency’ can be inferred for a water mist system in terms of performance or reliability. Prior to specification and installation, a water mist system should be tested to recognised and established international test protocol for conformity.
The benefit of sprinkler systems for supporting property protection and business resilience is recognised by UK insurers. Water mist systems are commonly not recognised.
All components of a sprinkler system are individually certificated – sourcing and installation of replacement parts is simple and the certification of the system is preserved. Water mist systems are certificated as a whole – if any part becomes unavailable, or the manufacturer no longer exists, the system becomes uncertifiable and will need to be replaced in its entirety.
Sprinkler systems are designed and installed to a common ruleset of unitised principles with detailed guidance on how to match protection against the commodity and storage system requiring protection – these have been confirmed by full-scale fire testing.
Water mist system designs are specific to the supplier and must be tested to recognised and international test protocol. Issues relating to the equivalence of performance of water mist systems compared to other active and passive fire protection measures have not been investigated. Aspects such as reliability, real fires history and long-term maintenance are largely unknown or unproven.