These systems are another tool in the arsenal of the fire protection system specialist for the control of fire in special hazards and have recently been granted Factory Mutual Approval for use in many applications. Fine water mist systems extinguish fires primarily by removing heat from the materials involved in the combustion process.
Water is applied to the fire in very fine droplets which appear to the observer as a dense fog.
The ratio of droplet surface area to water volume is large and conversion to steam occurs very efficiently. By timing the discharge and controlling the amount of water released via the microprocessor based control unit, these systems are capable of extinguishing fires with minimal water discharge in difficult fire protection applications such as turbine generators enclosures. The maintenance of the design concentration has always been a problem for gaseous agent fire suppression systems utilizing carbon dioxide or halon 1301 due to integrity of the turbine enclosures. The calculation of the amount of agent required to adequately account for leakage on any given turbine is a scientific guess at best. Fine water spray systems do not require a totally airtight enclosure to be effective.