Research reports and analyses
Low pressure water mist -
the modern approach in firefighting industry
Technical article - VID Fire-Kill ApS - April 2022
For the last thirty years, water mist fire protection has evolved from a theory to an increasingly widely accepted alternative to traditional water, foam or gas fire protection systems. Water mist offers better protection efficiency, significantly less water consumption and lower investment costs.
Water mist systems are a special category of fire protection systems that, depending on the class of fire hazard, can be designed to control, suppress or extinguish a fire. Their effectiveness is proven by full-scale tests for each class of fire hazard.
There are two main types of water mist systems - those that operate at low pressure (up to 16 bar) and others that operate at high pressure (from 50 to 140 bar). Both types of systems use a very fine water spray composed of micro-sized water droplets. Until recently, it was thought that droplet size and extinguishing efficiency were closely related, and that the smaller the droplets are, the more efficient the system is. And the smaller droplet size was automatically associated with the operation of high-pressure systems, giving them priority over the low-pressure water mist systems.
The modern approach to the development of water mist technology reveals many different factors on which the effectiveness of water mist systems depends.
These factors may be, on the one hand, the water mist spray characteristics such as distribution of droplet size; flux density, expressed as the amount of water released per unit volume / area per minute; spray dynamics, expressed in the speed and trajectory of the droplets. On the other hand, it is necessary to take into account the specific fire scenario (geometry of the room, type and size of flammable materials, ventilation conditions, ambient temperature, etc.). Factors such as enclosure effect, dynamic mixing created by the discharge by a group of nozzles, also affect the performance of water mist systems.
Due to this complexity of the fire extinguishing process, the relationship between the fire scenario and the characteristics of the system is not unambiguous, but very complex. Neither the droplets size nor the operating pressure determine the effectiveness of the system. Only full-scale fire tests prove whether a system can handle a certain risk.
Moreover, empirical studies show that water mist with a combined distribution of different sized droplets achieves higher efficiency compared to water mist composed of the same or even very small droplet size. For this reason, water mist systems are always selected on the basis of positive fire test results.
Why is the FIREKILLTM system so efficient?
The modern research with a combination of experimental and computational methods, the compilation of computer models and their validation by fire tests allow much more efficient and effective development of water mist systems. This approach was followed by VID Fire-Kill ApS when developing and creating the FIREKILLТМ system.
The FIREKILLТМ low-pressure water mist system is a complete solution for protection against many fire hazards in modern buildings and industrial facilities. The system includes a full range of equipment (nozzles, pumps, valves, etc.), documents and applicability according to CEN EN 14972, system manual for design, installation, operation and maintenance, certificates and approvals according to many standards, including third parties, as well as protocols of full-scale fire tests.
Compared to gas agents and traditional sprinkler systems, the low pressure water mist technology implemented in the FIREKILLТМ system shows a number of advantages, summarized in the following most important characteristics:
Completely safe for people;
Completely harmless to the environment;
Low investment price;
No damage or minimized damage of the extinguishing agent - water;
High efficiency for almost all fire classes, including special fire hazards.
The extinguishing efficiency can be explained by two chemical reactions that occur during combustion. The first chemical reaction (pyrolysis) takes place on the surface of combustible material, when under the influence of heat the combustible material begins to decompose and release flammable gases. The second chemical reaction (oxidation) takes place in the atmosphere above the surface of flammable
material, when under the influence of heat energy the oxygen molecules decompose and bind to the molecules of flammable gases. This process releases extra energy and thus maintains the combustion process.
Water mist affects both processes through several extinguishing mechanisms - primary and secondary:
1. Heat extraction:
Cooling of fire plume.
Cooling/ Wetting of the fuel surface:
2. Displacement of oxygen and other combustion gases:
Displacement of oxygen.
Dilution of combustion gases/ fuel vapor.
3. Heat transfer attenuation.
4. Kinetic effects.
Through specially designed nozzles, the system distributes water mist droplets at a certain speed and with a wide range of sizes, ranging from invisible to large droplets. The wide variety of droplets help to fight fire in many different ways at once. For example, the large droplets penetrate the flames and fall on the surface of the combustible material where they prevent flammable gases from being formatted. The medium sized droplets penetrate the fire, evaporate and create an inert environment, just where it is needed, in the heart of the fire. The small size droplets evaporate at the immediate vicinity of the fire, cool the atmosphere and block the fire spreading to the surrounding objects.
Thus, using four methods to eliminate the fire and its consequences, the system optimizes water use and the result is maximum efficiency.
Why is the FIREKILLТМ system the best solution for complex issues in fire protection?
The FIREKILLTM system is a complete solution for design, installation, operation and maintenance of fire protection systems in all kinds of buildings, as well as industrial and infrastructural facilities. The system includes pumps, valves, discharge nozzles - all designed to function as a special fire protection system. The system operates at low pressure typically up to 8 bar, producing water mist spray through a set of nozzles specially designed and approved for various fire hazards, including standardized hazard such as LH, OH1, OH2, OH3, OH4, HHP, as well as special fire hazards in industrial applications.
As a result of extensive research and development, as well as numerous full-scale fire tests, the company’s employees are confident in performance of their system.
The FIREKILLTM system is individually designed and tested to meet the highest standards in the firefighting industry. The main standards that currently define the requirements for water mist systems are CEN EN 14972, NFPA 750, VdS 3188 and BS 8489. Unlike the standards for sprinkler and gas systems, they do not follow prescriptions, but an approach based on test evidence for effectiveness in each application and fire risk. The test reports are published within the framework of approval standards such as FM 5560 and VdS 3883. In addition, the European standard CEN EN 14972 provides guidelines for development of new fire test protocols for special applications.
FIREKILLTM has been tested and approved based on existing fire test protocols for a wide range of applications. Moreover, it has several in-house developments of test protocols for special hazards in accordance with the annexes of the CEN EN14972 standard. The system has certificates of compliance from accredited laboratories, as well as certificates of approval from third independent bodies such as FM Approvals and DNV.
The system has four levels of certification. In addition to the fire tests, all components of the system have passed tests, which prove their strength and reliability. Apart from that, the production system is ISO 9001 certified and approved by FM, DNV/GL and Loyds Register MED-B.
The FIREKILLTM system is constantly supplemented by new successfully tested applications, whose fire scenarios are described in detail in the technical documentation and in the system manual for design, installation, operation and maintenance (DIOM) - an important document that provides complete instructions for successful implementation. These documents are approved by independent certification organizations such as FM Approvals.
The DIOM manual contains all important details of the system design such as nozzle type, distances, maximum mounting heights, minimum pressures, discharge times, application limitations and others. The fire test reports include important information about space geometry, fire loads, fire test scenarios, test conditions, system acceptance criteria, etc.
What are the benefits of implementing the FIREKILLТМ system?
The intelligent unique design of the FIREKILLTM system brings a number of benefits to the company’s clients and partners.
Based entirely on preliminary tests for various fire hazards, the system allows designers to create customized solutions that meet the specific requirements of customers and the characteristics of the protected site. The FIREKILLTM system covers almost all fire risks with the same maximum efficiency. The system provides reliable, environmentally friendly, completely safe and sustainable fire protection, which makes it the most economical and ecological solution in fire protection compared not only to traditional systems, but also to high pressure water mist technology.
The individual compact design, aesthetic nozzles, functional characteristics and resource efficiency allow more freedom in design and the ability to implement modern architectural concepts, which not only leads to satisfaction for engineers and architects, but also saves significant costs for clients and investors.
The FIREKILLTM system works cleanly and efficiently requiring minimal maintenance and technical support. The low-pressure technology allows perfect adaptation to structures with an installed sprinkler fire protection system. The unique nozzle design allows creating of customized concepts depending on local requirements or specific applications, as well as an easy integration into existing site structures.
The customers can also benefit from compact system equipment that provides small pump room sizes, small water storage tanks and small pipe sizes for easier integration into building structures, especially in projects to upgrade an existing fire protection system or creation of hybrid systems.
The system most often operates at pressures up to 8 bar, while using as little water as high-pressure systems, usually operating at pressures above 50 bar. The low pressure guarantees high reliability and strength, as in sprinkler systems, and at the same time contributes to lower installation, operation and maintenance cost. The system can be designed, installed and maintained with the same knowledge and skills as a conventional sprinkler system. Compared to high-pressure water mist systems, FIREKILLTM is stronger and more reliable, uses less electricity and, due to the larger nozzle orifices, does not need filtered water to operate smoothly.
The FIREKILLTM system is installed and maintained by trained and certified by the manufacturer partner organizations, which guarantees the high quality and reliability of each specific installation. And the result of the implemented system is always positive and can be summarized in the long-term benefits that it brings to all involved in the construction and investment process - investors, owners and users of buildings.
Long-term benefits of implementing the FIREKILLTM system
to investors, owners and users of buildings:
100% environmentally friendly and sustainable solution;
100% safe and secure solution for people;
100% reliable customized solution;
Effective solution for almost all fire hazards in modern buildings, industrial facilities and infrastructure;
Effective solution for specific applications where other fire protection systems do not offer reliable protection;
Reliable protection for tangible assets and equipment, business continuity;
Long-term solution - unlike gas extinguishing agents, there is no risk of regulatory restrictions on future use;
One complete solution to all fire risks in the whole building;
Fast return on investment;
Low insurance premium;
Expertise from a global supplier with more than 25 years of experience in the development, production and sale of low-pressure water mist systems.