There is no need for anyone to tell how dangerous any fire is, and how hard it is to fight fire, which is capable of destroying the results of many years of labor of human hands together with man in a matter of hours. However, it used to be. However, time goes on, and science develops with it. Today, people have learned to fight fire and learn about the threat of a fire at a time when the flame just appeared, and it is not difficult to deal with it. All this became possible with the advent of such a device as an automatic fire extinguishing installation.
What it is? What are the goals?
Automatic systems and installations for fighting fire, as a rule, are part of a complex of devices designed to ensure the general fire safety of a building or structure. Their main purpose is to prevent the spread of flame and enter the fight against the elements at the earliest stages.
These devices are not required components of the fire fighting system. However, in such facilities where there is an increased risk of fire and the rapid spread of flame, as well as where there is no possibility of emergency evacuation of people who are in the affected area, automatic fire extinguishing (UAP) installations can be said to be simply irreplaceable.
An automatic fire control system can be called a set of devices that can independently activate when the parameters and factors controlled in the protected zone are exceeded relative to threshold values.
A distinctive feature of these devices is their automatic fire alarm functions . These elements, usually included in the general fire control system, should ensure the achievement of one, or better several goals at once, the main of which are:
- liquidation of the flame at the protected facility until the critical values of the ignition factors are reached;
- elimination of fire before the fire resistance of building structures at the facility;
- liquidation of the fire earlier than the maximum damage to property and material values;
- termination of combustion processes before there is a danger of destruction of technological installations with which the protected object is equipped.
Further, among the most important functions that automatic fire extinguishing installations must necessarily perform, there is such as emergency assistance in providing a safe stay zone for people on the premises.
Options for existing automatic installations
Currently, there are many options for automatic installations to combat fire. They can be classified according to several parameters. By design, these devices can be modular, modular, deluge and sprinkler. By the method of extinguishing the fire, they can be voluminous, in area and local.
By the method of operation (or start) of the installation, they can be divided into manual, automatic and various drives (electric, hydraulic, pneumatic, mechanical, combined).
By such a factor as inertia, automatic fire extinguishing systems can be divided into ultra-fast, high-speed or low inertia, medium inertia and increased.
In addition to the foregoing, fire extinguishing installations are classified by the duration of the extinguishing agent. They can be of pulse action, short-term, medium duration and long-term exposure.
However, both among specialists and among ordinary consumers, the most famous is the classification according to the type of substance used to extinguish the flame. According to this factor, automatic fire alarm and fire extinguishing installations can be divided into water, foam, gas aerosol, powder and steam.
Foam-based plants
The automatic installation of foam fire extinguishing is one of the most complex, because it additionally includes mechanisms that convert the powder from a specific composition into foam (they are called sprinklers or steam generators). In addition, in foam installations (in particular, in a fire pipeline), special containers or tanks should be provided in which concentrate for the production of foam or an already prepared composition will be stored.
The use of the finished composition and the preparation of foam directly in the process of extinguishing a fire are two incomparably different principles of AUPT operation. Each of these methods is characterized by both its positive and negative sides. If the border between them is purely arbitrary, then we can say that the automatic fire extinguishing installation, in which the concentrate for the preparation of foam and the water supply are stored separately, will be more effective for protecting large objects.
Units with a ready-to-use composition are more suitable for eliminating flames at small-area facilities, because there are a number of drawbacks that occur when storing sufficiently large volumes of foam mass. Of the most significant, the following can be distinguished. The finished composition has a short shelf life, that is, it must be changed regularly, which entails an increase in cash costs (and in proportion to the size of the tank). Further, if the required pressure is able to provide a fire water supply, then it makes no sense to invest in the construction of a large tank. In addition, the contact of the foam composition and concrete is unacceptable, that is, it is necessary to cover the inner surface of the storage tank with epoxy mastics, which, again, increases the cost. And large tanks significantly complicate the processes of disposal of old foam and replacing it with a new one.
Automatic installation of foam fire extinguishing will prove to be most effective in conditions of use in chemical and petrochemical enterprises, which store a lot of flammable liquids. It is also justified to use them in warehouses and in hangars with equipment, that is, where there are usually few people and there is no way to quickly evacuate material values.
Fire fighting water systems
Installations that use water in their work are the most versatile in comparison with all others, since they can be used where the safety of people and the possibility of their emergency evacuation is a priority over all others (offices, government agencies, etc.).
Installations that use water to extinguish fires can be divided into two types: local (sprinkler) and protecting the entire building as a whole (deluge).
The automatic installation of sprinkler fire extinguishing (from the English sprincle - "drizzle, spray") is equipped with a fully autonomous response system. When a fact of temperature increase is recorded at any point on the surface to be protected, it (UAPT) activates itself and sends a stream of finely atomized liquid as close to the heat source as possible.
If the choice of UAPT is preferable to their water appearance, it is necessary to pay attention to the type of control unit (“dry” or “wet”). The first ones are mainly used on unheated objects and premises, and the second ones (“wet”) - where the temperature is never below zero.
Water fire extinguishing systems (automatic), unlike sprinkler systems, are never autonomous. They always work in tandem with a fire alarm system that activates them. Drencher devices are not equipped with sensors that would determine the location of the source of increased heat dissipation and coordinate their work in this direction. These installations during operation cover with water all accessible surfaces in the protected room.
If preference is given to water-based versions of UAPT, it must be remembered that water is able to react with some organometallic compounds and compounds. The result of such reactions can be the release of toxic substances into the air, which, of course, will create conditions that impede the evacuation of people, and can harm their health. For this reason, the use of automatic water-type fire extinguishing installations is generally unacceptable in those industrial-type facilities where coal, iron, metal carbides, etc. are involved in technological cycles. Also, the necessary effect will not be achieved in cases where water-based UAPTs used to eliminate flame in rooms where flammable liquids with a combustion temperature not exceeding 90 degrees are stored.
Expansion valves
Currently, a new unique technology for the operation of a water fire extinguishing installation has been developed and successfully implemented. New generation automatic devices do not cover all accessible surfaces with a thin layer of water, but spray liquid in small droplets directly into the flame. The liquid evaporates, thereby binding the fire. Such funds are called fine spray water fire extinguishing systems (TRV). In addition to bonding open flames, evaporation of the liquid leads to increased vaporization. Steam, in turn, reduces the volume of free oxygen contained in the enclosed space and thereby suppresses the possibility of combustion processes. The result of the impact of such installations is the maximum localization of the source of ignition, its separation and complete extinction of the flame.
Automatic fire extinguishing installations using fine spray technology work effectively in those places where flammable compounds and liquids are stored. Also, such AUPTs are able to stop the combustion process, provoked by sudden changes in voltage in the mains. In such cases, most often you have to fight fire when extinguishing electrical equipment that is energized. Provided that the water spray and the burning object are at a distance of at least 1 m, the permissible voltage values can reach 36,000 V.
In addition, a cloud of tiny droplets of water is an excellent absorbent that binds carbon monoxide fumes, ashes and other particles that can cause serious harm to the human respiratory system. The process of extinguishing a fire by installing an expansion valve does not prevent the evacuation of people (if necessary) and the protection of material assets.
Of the minuses of such devices is the inability to use them in places where there is a risk of contact with organometallic compounds.
Gas type plants
Modern liquefied chladones or compressed nitrogen, argon, inergen give a person the opportunity to defeat fire in those places where liquid means cannot be used for these purposes (rooms where a short circuit may occur , information stores, libraries, museums, aircraft).
In rooms protected by gas AUPT, upon the occurrence of a trip, devices and mechanisms of light (the words "Gas - go away!" And "Gas - do not enter!") And an audible fire warning should be turned on. These are the requirements of the GOST system.
Gas extinguishing installations (automatic) create an environment where the development of fire is impossible in principle. This is very convenient for rooms with a high risk of flame spread. If the fire area is small and significant gas volumes are not required, such fire extinguishing is possible even without preliminary evacuation of people. However, one must know that gas in large doses can cause serious damage to human health.
The use of gas systems to extinguish fires is justified in cases of fire in the premises of power supply, at thermal power plants and state district power plants (extinguishing generators in the case of using hydrogen-type cooling), at facilities for the production of low-combustible materials, in long-distance transport, in warehouses with valuables. In libraries and museums, such installations can be used provided that exhibits and rarities are stored under glass.
It should be remembered that the installation of automatic fire extinguishing based on gas will not be effective where materials can burn without the participation of oxygen in this process. Such devices are not used in cases where materials are prone to spontaneous combustion and decay (wood shavings, rubber, cotton, etc.), for certain types of metals capable of reacting with gases, for pyrophoric materials.
Powder based fire extinguishing systems
Currently, most often (about 80% of cases), all previously described types of automatic fire extinguishing installations are inferior to powder-type UAPTs. This breadth of application is due to a number of advantages. Firstly, these devices are quite versatile (it can even be used to extinguish electrical installations). Secondly, the shelf life of the reagent is quite long; its disposal is not very difficult. In addition, such UAPTs have a high temperature limit and are non-toxic.
Powder-type plants are able to deal with class A, B, and C fires, which significantly expands their capabilities when eliminating fires at remote sites, where sometimes you have to wait a long time for help.
An automatic fire extinguishing installation using powders is effective for fires at oil and pumping facilities, when working with electrical points and assemblies. However, the desired result will not be achieved if materials are burned which do not need oxygen to maintain this process, as well as those that are prone to spontaneous combustion and decay.
Powder fire extinguishing devices are not compatible with smoke ventilation systems. And since the latter must be present where people are constantly located, the share of powder UAPT accounts for industrial facilities, warehouses and tunnels.
Aerosol type devices
The automatic installation of aerosol fire extinguishing is a rather highly specialized device. They can not be used for extinguishing fires of potentially explosive substances, as well as where people are constantly present. The composition of the aerosol itself is, in principle, harmless and is not capable of causing any serious harm to health. However, acting independently, automatic fire alarm and fire extinguishing installations based on aerosol do not allow people to see where the escape routes are.
Due to the high efficiency of these UAPTs, people can wait until the fire is completely eliminated in the building. But here it is important to trace and take the necessary measures in order to prevent the explosion of the plants themselves due to the large amplitude of fluctuations in internal pressure relative to external temperatures.
Aerosol-type devices have proven themselves in those cases where it was necessary to extinguish the fire caused by a malfunction in the electrical network. Such installations are also effective in combating fires of technogenic origin. This is an ideal tool for ensuring fire safety for large vehicles, oil farms, etc.
However, such an automatic fire extinguishing and alarm system using aerosols is not able to completely eliminate decay in the inner layers (porous, fibrous materials) and combustion without the presence of oxygen.
Autonomous response and exposure settings
In most cases, automatic stationary fire extinguishing systems have been described above, but along with them there is the concept of an autonomous system for fighting fires. What it is?
An autonomous installation is capable of independently detecting a hot spot of increased heat transfer and deciding on the need to activate the fire fighting process. Such devices can fully include UAPT water and gas species. Such systems, as a rule, are equipped with special sensors that are sensitive to temperature increase or identify the corresponding particles in the air. If such factors are fixed, the sensors transmit a signal to their own panel for analysis and commands in order to activate the workflow (in case of a clear fire hazard). , : « – – ».
, , , , , . , , . , . , .
, , , , . , ( , , . .) , .
Price range
, , , , , – , .
, . : , . , .
The most expensive systems are the fine-jet spraying of water, which in no way prevents the evacuation of people, allows them to wait out a fire in the room until it is completely eliminated, and do no harm to material values. Liquid droplets are so small that in contact with the flame evaporate without reaching the surfaces. Also, in the process of fire fighting, steam is formed that prevents the spread of fire and lowers the temperature in the room.