A Detailed Analysis Of Gas Extinguishing Systems

Gas-Extinguishing-Systems-ExplainedEvery five minutes at one of the ignition occurs. Common Causes – wiring.

One tiny blown wiring inside the computer or a server in data center or IT infrastructure is sometimes enough to start a smoldering fire. If the fire is not recognized and effectively suppressed even at the stage of its origin, in addition to fire, heat and smoke can highly destroy existing equipment. Since nowadays almost all the activities of enterprises and institutions dependent on IT processes, hosted server failure can paralyze their work for a long time. As a result, it is possible that even the most patient customers will have to switch to another provider. According to research conducted in the India, about 75% of all businesses hit by large fires, were forced to declare bankruptcy – not only because of the devastation caused by fire (they are usually covered by insurance), but just because of such consequential damages.

If the premises, tightly crammed IT equipment are filled with water, the damage is even greater, since the consequences of such destruction, and primarily short-circuit, resulting in data loss, fatal errors, not only for exchanges or services related to security, such as the Ministry of Emergency Situations but also for IT service providers, banking, stock market and etc.. Gas fire suppression system eliminate fire without such troubles. Gas penetrates to all corners of the room – even there, where we could not get a drop of water. In many cases, after a quick fire suppression operation of the server room, you can continue immediately after airing.

The first studies of the ability of carbon dioxide to extinguish flames dating back to the XVIII century. In 1929 in Germany, it was put into operation (The first installation of fire-fighting was done) using CO2, and later created safe humans extinguishing gases. Starting from the 50s were considered the standard of halons (CFCs – halogenated hydrocarbons that can put out a fire before their concentration reaches harmful values), but 20 years later it became clear that this class of molecular compounds damage the ozone layer. As a result, in the beginning of 1994 in Germany, they were refurbished or dismantled all Halon fire extinguishing system.

Currently argon, nitrogen, carbon dioxide are used in fire extinguishing installations, so-called inert (non-reactive) gas, and mixtures thereof, and HFC-227ea, FK-5-1-12 and HFC-23 – halogenated hydrocarbons or chemical extinguishing gases. All these substances are colorless, do not have electrical conductivity, when used properly and do not leave any traces. To prevent harm to human health, carbon dioxide, and often inert gases of odor, that is mixed with aromatic substances. Because of this, people may feel the presence of these gases, which in themselves are odorless.

The extinguishing effect of these substances is based on three different mechanisms:

  • Firstly, they are to some extent reduce the percentage of oxygen in the room.
  • Second, the gas molecules absorb the heat generated by the combustion reaction (specific heat capacity).
  • Finally, the effect of chemical extinguishing gases is mainly based on the decay of the molecules in the flame and in contact with hot surfaces. Decomposition products (hydrogen fluoride, and others.) Interfering with the reaction of combustion.

Decomposition products are toxic and chemically aggressive gases. As the flue gases, they represent a potential threat to the health of people and their property, but when used properly, their concentration is safe. The extinguishing gas quickly fill the room and the fire is been extinguished and the additional decay products do not appear.

As in other cases, when using gas extinguishing systems required to protect personnel. At least once a year should have trainings for employees of the company for correctly perceived risks associated with the use of fire extinguishers. Next to the rooms, in gas fire suppression system, it is necessary to place warning labels. Before the premises is supplied with gas, should give a visual or audible warning signal.

Following the discovery of fire in the room, partially closed or open, the control system starts the installation of gas fire, which saturates the air with fire extinguishing gas, bringing its concentration to such an extent as to ensure effective quenching. In rooms with IT equipment such concentration must be maintained for at least ten minutes, which will prevent re-ignition (backfire).

Typically, the installation consists of extinguishing agent storage tanks equipped with valves and check valves, control equipment for the content containers, and pipes of the distribution network for the supply of extinguishing agent to the nozzles located within the premises, on the ceiling, in a double floor in equipment rack. Bandwidth distribution manifold and the nozzles must be such that the gas is distributed in time to within the prescribed time.

Detection of fires is usually carried out by automatic responsive sensor, for example, to smoke particles in the air. They are placed on the ceiling or in the vicinity of potential ignition sources. Since emitted during the combustion gases always rise up, a ceiling-mounted smoke detectors in most cases provide a fast and reliable supply of the signal. However, in server rooms where ventilation and cooling systems create strong air currents and eddies, the smoke does not accumulate under the ceiling and uniformly distributed throughout the room.

In such circumstances, ceiling sensors detect too late occurrence of fire, so the server rooms in data centers are additionally equipped with a second set of detectors installed under the raised floor. As an alternative, the smoke suction system in which air from the room is supplied through the auxiliary piping directly to the sensor. Additional requirements for fire-fighting installations may arise in the presence of isolated hot and cold aisles, where it is necessary to ensure an even distribution of the extinguishing agent.

To gas fire suppression system is guaranteed to cope with the task, so you must isolate the room where it is installed, from the environment to a fire or other dangerous situations, it is not affected. In addition, before the start of the fire extinguishing agent system should provide closing doors, gates, windows and turn off ventilation.

The optimum would be absolutely gas-tight room, but the supply of extinguishing gas leads to excess pressure, so the lack of discharging holes may cause damage. Therefore, regardless of the extinguishing gas is used for gas extinguishing systems all necessary openings for pressure relief of the protected space to the outside. In practice, often have to see a situation where due to the lack of such openings shifted entire walls and closed doors swung open, or escaped from the door frames. Properly arranged hole to eliminate excess pressure is always calculated on the maximum mass flow. This information is provided by, for example, specialized software for the design of gas extinguishing systems.

Gas extinguishing system will save human lives and equipment in the building just when they are capable of creating in the area of fire-extinguishing concentration of extinguishing gas required (so-called fire-extinguishing concentration) and maintain it enough time. Therefore, the design of any gas fire suppression system should pay particular attention to this factor. Concentration for extinguishing combustible materials and different extinguishing gases to be determined empirically, as it varies depending on the substances used.


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