Water Mist in High or Low Pressure (respectively 100 and 5 bar) is the most effective and safe extinguishing system that currently exists on the market. At present, there is no legislation in Europe that regulates the Water Mist systems, they are therefore manufactured according to American legislation, thanks to the Derogations granted by the Relevant Authorities.
Dispensing the water in droplets, which are a few microns in diameter, makes it possible to accelerate the cooling process of the flames and introduce the concept of saturation to the fire, where water replaces the oxygen that would feed the combustion. It should also be noted that, thanks to the high pressures involved, these benefits are obtained with smaller pipes and, in a world where water is an increasingly valuable resource, the amount of water is greatly reduced in comparison to conventional sprinkler systems.
The use of water mist for fire extinguishing is important for the following effects:
As a result of the water separation in a myriad of microscopically sized droplets, a reaction surface is created through which the heat produced by the fire is absorbed. One litre of water requires 335kJ to pass from 20 °C to 100 °C and an additional 2257kJ to transform into vapour. Water is the extinguishing agent with the greatest known heat absorption capacity and can be used to particularly good effect in the water mist technologies due to the large reaction surface, compared to the conventionally known techniques of extinguishing.
With evaporation, water increases its volume up to 1640 times, which causes a depletion of oxygen in the air to the fire source. In this process, the inerting fire extinguishing medium is not transported to the source of the flame from the outside, but it is only produced in proximity to the fire. Unlike the use of extinguishing gases, the use of water mist systems does not require completely sealed rooms.
As sufficient energy potential is issued, the source of fire can be flooded with vaporised water in one fell swoop, so that a fire can be suffocated in a matter of seconds. This takes place thanks to the combination of various extinguishing effects. The oxygen content is reduced from 16% to 6% in volume, in close proximity to the origin of the flames, while the normal oxygen content (about 21%), is maintained in the rest of the room.
The water drops that lie between the flames and the combustible surface will strongly reduce heat irradiation. The combustion rate decreases and the overheating of the possible sources of the surrounding flame is reduced.
A decisive factor for this effect is also the generation of a sufficient quantity of microscopic droplets whereby the reflecting capacity increases with the decrease of the size of the drops. "In comparison with gas extinguishing systems, the use of water mist extinguishing systems, does not require completely closed spaces". The extinguishing effect described above becomes effective, to a different extent depending on the scenario produced by the fire, and at the same time the flames can be extinguished with very small quantities of water
A non-secondary separation effect of combustion gas particle washing can be achieved, as most of the combustion gas components are absorbent in nature and tend to adhere to the smallest droplets. The same applies to the soot particles that bind themselves to the water droplets.
In case of the previously described separation effect, the tiny water droplets reduce heat radiation on the surrounding objects. This prevents the possible spread of flames and can be exploited, for example, to create fire-resistant barriers.
Water mist systems can be designed so that incandescent (metallic) surfaces are struck by the water mist in an extremely uniform fashion. In this way it prevents the deformation of such surfaces due to uneven cooling. Thanks to the low conductivity of water mist, especially when using demineralised water, it is possible to fight fires in the vicinity of electrical installations.
The ability of the water mist to reduce the temperature more quickly than any other extinguishing agent and to wash away all of the residual gas is of particular importance in the protection of individuals. Moreover, a survey conducted by the US Agency for Environmental Protection and the German National Association for Fire Protection, has clearly shown that water, used as an extinguisher, does not constitute a risk factor for people by any means. Under normal circumstances, even a reduction of oxygen in the air is not a danger because it occurs only in the vicinity of the fire.
Another aspect of the water mist systems is that the fire is usually extinguished at a harmless oxygen concentration of about 16-18% by volume, because the suffocation effect is always present in combination with other extinguishing effects.
It follows that there can be no critical hazard for people, as a result of water mist. Water mist systems can be activated without notice, except in special situations. Access by the Fire Department in the affected premises with the discharge of a water mist systembecomes considerably safer.
Most suitable for applications in flood systems.
It can be equipped with a maximum of 5 micro-nozzles according to the project requirements by offering great versatility of flow.
The head is made of stainless steel in order to better adapt to the stainless steel pipes.
Most suitable for applications in wet systems or preventive action.
They can be equipped with a maximum of 4 micro-nozzles according to the project requirements by offering great versatility of flow. The head is equipped with a rapid response of 36 (ms) 0.5. It offers a wide range of temperatures, from 57 °C up to 141 °C.
When connected to the pipe, this nozzle allows the detection of the fire by means of a phial, allowing for activation when the pressure in the pipe exceeds a minimum value (60 bar). In this way, it is possible to design extinguishing systems to include detection.
As well as in the closed head model, it can be equipped with micro-nozzle according to the specific requirements.
The low pressure atomised water is characterised by a large surface area that absorbs the heat and effectively extinguishes the fire with a low water consumption
The larger water droplets extinguish combustible material while the smaller ones cool and neutralise the combustible gases
The ES_liquid additive reduces the surface tension of the water and allows the formation of a fine mist at low pressure
The insulating film formed by the extinguishing agent lowers the chance of new ignition.
The WMEA800K20P4 nozzles are used in maritime applications and are approved by:
Generally, WMEA800K20P4 are tested in accordance with IMO Resolutions A.800 and FM "Draft Performance Requirements for fine water spray systems for the protection of light hazard occupancies" however they can also be supplied according to NFPA 750
Material: Brass MS58/NiSn
Installation: low-pressure water mist fire extinguishing systems are always vertical
WME4377 and WME1866 nozzles were tested in accordance with IMO 913 and IMO 668. The nozzle is low pressure, versatile, it is a dry system and can be equipped with a phial.
The nozzle is protected by its own sleeve.
Testing and approvals: